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Volumen 29. Numero 1. 2010

LIMNETICARevista de la

Asociacion Iberica de Limnolog�a

Pond conservation from science to practice:3rd European Pond Workshop

Guest Editors:

Maria Rosa Miracle (University of Valencia, Spain)

Beat Oertli (University of Applied Sciences Western Switzerland, Geneva)

Regis Cereghino (University of Toulouse, Toulouse, France)

Andrew Hull (Liverpool John Moores University, UK)

With the colaboration of:

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Deposito legal: V-2404-1986

ISSN: 0213-8409

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Limnetica, 29 (1): x-xx (2008)Limnetica, 29 (1): 1-8 (2010)c© Asociacion Iberica de Limnolog�a, Madrid. Spain. ISSN: 0213-8409

Preface: conservation of european ponds-current knowledge andfuture needs

Maria R. Miracle1,∗, Beat Oertli2, Regis Cereghino3 & Andrew Hull4

1 Dept. Microbiologia i Ecologia. Institut Cavanilles de Biodiversitat i Biologia Evolutiva. University of Valencia.46100-Burjassot (Valencia). Spain.2 hepia Geneva University of Applied Sciences Western Switzerland, CH-1254 Jussy-Geneva, Switzerland.3 Universite de Toulouse, EcoLab Laboratoire d’Ecologie Fonctionnelle, UMR5245, 118 route de Narbonne,F-31062 Toulouse cedex 9, France.4 Liverpool John Moores University. Clarence St. L3 5UG, Liverpool, UK.2

∗ Corresponding author: [email protected]

ABSTRACT

Preface: conservation of european ponds-current knowledge and future needs

Ponds are common elements of the landscape with an important role in the global processes of biosphere and biodiversitypreservation. Recent research indicates that ecological characteristics of ponds are different from other inland water systems,but scienti�c knowledge is still insuf�cient and poor compared to lakes and rivers. Therefore, whilst indicators and conser-vation tools have been developed for most aquatic systems, there is also a gap between existing basic information on pondecology and applied research. The European Pond Conservation Network (EPCN) with the aim of strengthening the linksbetween basic and applied research and pond management organized its 3rd biennial meeting in Valencia (Spain) with thetheme “Pond conservation: from science to practice”. We present a selection of papers from this conference, which cover thethree main topics of the sessions: (1) Management and conservation in practice, (2) Pond ecology at different scales and (3)Temporary ponds. The articles presented develop techniques for assessing the ecological status of this type of ecosystems,evidence the importance of ponds in a global scale, indicate that their conservation must take into account their spatial ar-rangement in networks, discuss environmental factors that are relevant to biodiversity conservation and provide informationon different research areas such as biogeochemical processes, evolution of aquatic biota and community ecology.

Key words: Ponds, biodiversity, conservation, temporary ponds, global change.

RESUMEN

Prefacio: conservacion de las charcas europeas-conocimiento actual y necesidades futuras

Las charcas son elementos habituales del paisaje que tienen un importante papel en los procesos globales de la biosfera y enla conservacion de la biodiversidad. Investigaciones recientes indican que las caracter�sticas ecologicas de la charcas sondiferentes de las de otros sistemas acuaticos, pero los conocimientos cient��cos de ellas son todav�a insu�cientes y pobrescomparados con los de los lagos y r�os. Por lo tanto, mientras que hay un desarrollo avanzado de herramientas para laconservacion de la mayor�a de los ecosistemas acuaticos, subsiste un retraso entre los conocimientos basicos de ecolog�ade las charcas y los aspectos aplicados para su correcta gestion. La Red Europea para la conservacion de las charcas(EPCN) con el objetivo de estrechar la relacion entre el conocimiento fundamental y aplicado y la gestion de las charcasorganizo su tercera reunion bienal en Valencia (Espana) con el lema “Conservacion de las charcas: de la ciencia a lapractica”. Presentamos aqu� una seleccion de los trabajos expuestos cubriendo los tres topicos principales de las sesiones: (1)Gestion y conservacion en la practica, (2) ecolog�a de las charcas a diferentes escalas y (3) charcas temporales. Los art�culospresentados desarrollan tecnicas para la identi�cacion del estado ecologico de este tipo de ecosistemas, ponen de mani�estola importancia de las charcas en los procesos globales, indican que para su conservacion hay que considerar su distribucionespacial en redes, discuten los factores ambientales relevantes para la conservacion de la biodiversidad y proporcionaninformacion sobre diferentes areas de investigacion como procesos biogeoqu�micos, evolucion de los organismos acuaticos yecolog�a de comunidades.

Palabras clave: Charcas, biodiversisidad, conservation, charcas temporales, cambio global.

2 Maria R. Miracle et al.

INTRODUCTION

In Europe, ponds are the most widespread aquatichabitat and collectively dominate the total areaof continental standing waters. This, that isevident especially in Mediterranean countrieswhere lakes are very scarce, has not been takeninto account in local environmental studies andeven less in studies of biosphere plumbing. The“emerging role” of ponds is in the title of the �rstcontribution to this issue (Downing 2010), whichmakes evident, based on recent and improveddata, that ponds collectively not only have moresurface area than large lakes, but are also moreimportant in storing carbon than large lakes, thushaving a signi�cant role in the Earth’s carbon bal-ance and climate change. In addition, ponds alsoplay many other valuable roles such as enhanc-ing biodiversity, not only of aquatic organismsbut also of terrestrial organisms that depend di-rectly on these ecosystems as well as other indi-rect bene�cial effects such as mitigating diffusepollution or regulating temperature and humid-ity. In terms of regional diversity, a network ofponds has been found to make a greater contri-bution than lakes or rivers (Biggs et al., 2005)and the existence of important interactions be-tween species composition of different pond siteshave been appreciated, when large spatial scalesare considered (Briers & Biggs 2005). However,knowledge on ponds is only beginning and sincerecent studies have evidenced marked differenceswith lakes, we are aware that knowledge is insuf-�cient and much lower when compared to otheraquatic systems. There is a need therefore for fur-ther research on the organization and processesnot only within ponds, but also among them.

Despite the recent increase in the interest ofponds and awareness of their vulnerability todegradation and fast disappearance of many ofthem, their protection is still inadequate. For in-stance, the most substantial piece of water legis-lation constituted to protect our waters, the Eu-ropean Water Framework Directive, does not ap-ply to water bodies of less than 50 ha, in mostMember States, although in some nations, as inSpain, a few smaller lakes have been exception-ally included, due to the fact of the low number

of natural water masses with an area greater thanthe 50 ha. Accordingly, this does not include anyadditional protection for important ponds. Someponds, however, are protected under EuropeanCommunity legislation as providing a home forprotected habitats listed in Annex I and protectedspecies listed in Annex II and Annex IV of theHabitats Directive 92/43/EEC, mostly to the ben-e�t of Mediterranean ponds. One step forward,however, would be to modify the Directive torecognize ponds or pond areas as an additionalwater-body type to be protected (EPCN, PondManifesto, 2008). Large-scale loss of these habi-tats, especially in the more arid Southern Euro-pean countries, will be critical not only for con-servation of aquatic and amphibious organismsbut also to ameliorate climate change and also tomaintain a connected landscape, because ponds,although small, constitute a series of vital step-ping stones through the landscape as well as pro-viding many bene�ts to surrounding ecosystems.

On the other hand, a number of pond conser-vation initiatives have been undertaken in somecountries. In order to strengthen these, coordinatetheir activities and develop a framework of the-oretical and practical knowledge for pond con-servation, the European Pond Conservation Net-work (EPCN), was established at the �rst Eu-ropean Pond Workshop in 2004. This workshopwas held in Geneva (Switzerland), devoted to“Conservation and monitoring of pond Biodi-versity” with the objective of synthesizing re-cent basic and applied knowledge on the topic.One of the main outcomes from this initial meet-ing was the launching of the EPCN “to promotethe awareness, understanding and conservation ofponds in a changing European landscape” (Oertliet al., 2004; 2005a). The EPCN is a Europeannetwork of people and institutions involved in ba-sic and applied scienti�c research on pond con-servation as well as a range of stakeholders in-volved directly or indirectly in any aspect of pondconservation. The second European Pond Work-shop was devoted to “Conservation of pond bio-diversity in changing European landscape” andwas held in Toulouse (France) in 2006 where themain objectives were focused on understandingpond ecology, the added value of ponds and pond

Preface 3

management (Nicolet et al. 2007, Cereghino etal. 2008). The working sessions of this meet-ing were used to formulate the Pond Manifesto(EPCN, 2008), which had already been draftedat the �rst European Pond Workshop in 2004.The Manifesto sets out the case for the conser-vation of ponds, reveals the threats they face andoutlines a strategy for their conservation in Eu-rope, based on the knowledge and experience ofresearchers and practitioners. The Manifesto wasdelivered at the third EPCN conference in Valen-cia (Spain) and can be downloaded from the web-site of the EPCN (www.europeanponds.org).

Since the �rst workshop the network has beenconsiderably active and has held biennial meet-ings. This special issue provides a sample of thepapers presented at third meeting of the EPCNin Valencia (2008). Another selection of papersfrom this meeting has been published in a specialissue of Hydrobiologia (Oertli et al., 2009) andwill also be collected in a volume from the series“Developments in Hydrobiology” (together withpapers from the second European Pond workshoppublished in Hydrobiologia 597, 2008).

THIRD EUROPEAN PONDWORKSHOP:SPECIAL ISSUE CONTENT

The third European Pond workshop calledfor contributions on Pond conservation: fromscience to practice, with the aim of bringingtogether researchers, managers and practitionersto exchange information, concerns and viewson common topics under different perspectivesto strengthen knowledge on pond ecosystems.It was organized in Valencia under the aus-pices of EPCN by the Generalitat Valenciana(Conselleria de Medi Ambient) as an actionincluded in the European Union Life-Natureproject on “Restoration of priority habitats foramphibians”. A total of 123 communicationswere presented, 38 as oral presentations and85 as posters (which can be downloaded fromhttp://campus.hesge.ch/epcn/posters valencia08.asp). The meeting was structured around threetopics: (1) Management and conservation inpractice, (2) Pond ecology at different scales and

(3) Temporary ponds. In addition, two specialworking sessions were included in the confer-ence programme. The �rst session focussed onPond management success stories and, after thepresentation of case studies where successfulmanagement had been carried out, was devotedto understanding how we measure “success”and what could be learnt from managementfailures. It was proposed that the EPCN websitecould store pond management stories whethersuccessful or not. The second session –Linkingpond management to scienti�c knowledge– wasfocussed on ways in which better links could beestablished between scientists and practitionersin order to coordinate fundamental and appliedresearch and develop management practices ona scienti�c basis. The main issue discussed wasways in which the �ow of information betweenmanagement and research could be improved.This question is important for two reasons.Firstly, practitioners usually do not publishthe results of their practices and are thereforenot available to the scienti�c community and,secondly, there is very little applied research onpond management in scienti�c projects.

The papers selected for this issue cover thethree main topics of the meeting. The study ofponds in a global scale is a new and very de-sirable perspective, which was the theme of the1st keynote lecture of the meeting. In this lec-ture Downing (2010), based upon recent devel-opments in data acquisition and mathematical ap-proaches, clearly demonstrates the importance ofponds in global cycles, since they are small butnumerous with a disproportionally high intensityof many processes. This review paper updatesand illustrates with numbers the global balance ofburial and evasion of carbon and the role of pondsin carbon processing. It also opens a great ar-ray of suggestions on global limnology and ecol-ogy and shows the need to integrate ponds in anystudy of global processes in the biosphere. Pondsare important beyond their local and regionalscale, playing a signi�cant role in global biogeo-chemical cycles and biodiversity maintenance.

The growing interest in temporary environ-ments was re�ected in the 2nd keynote lecture inwhich Brendonck et al. (2010) started the session


on temporary ponds with a well documented re-view of a large series of studies that these authorshad undertaken in a series of small ephemeralfreshwater rock pools. They indicate how thesepools, which usually occur in clusters with differ-ent spatial patterns, can be used as model systemsto study biological, evolutionary and ecologi-cal processes. In addition to the valuable resultsfrom their studies together with methodologicaldescriptions, their paper includes attractive con-ceptual approaches and perspectives on patternsof species dispersal, meta-populations and meta-communities, as well as disturbance and commu-nity succession. Recent work, based in part onmetapopulation concepts (Hanskii 1999) has evi-denced the importance of the interactions, mainlythrough dispersion, between ponds forming partof networks (Briers & Biggs 2005). The hetero-geneity and gradients of environmental charac-teristics that display many diminutive idiosyn-cratic ponds, highly affected by surrounding lo-cal factors of their small catchment area, main-tain a high regional biodiversity (Jeffries 1998),which may be richer than in other aquatic sys-tems such as rivers, streams or ditches (Williamset al., 2004). Several contribution in past work-shops (Cayrou & Cereghino 2005; Jeffries 2005;De Bie et al., 2008; Oertli et al., 2008) have rein-forced the idea that pond networks –pondscapes–,should be considered in any conservation strat-egy and the spatial and temporal scales shouldbe broadened when developing management pro-posals. This large scale view is especially sig-ni�cant in temporary ponds (Pretus, 2009). Thebene�ts of the pond landscape view for tempo-rary pond conservation are illustrated in this issueby Diaz-Paniagua et al. (2009) integrating pub-lished and new data to describe the high speciesrichness and wide community assembly variationamong different ponds and years, dependent on�ne gradients of hydrological and/or other factorsfound in the large numbers of temporary ponds ofDonana National Park (Southern Spain).

The study of temporary waters is far less de-veloped than the study of other aquatic habitatsand basic descriptions of these habitats is vi-tal. Temporary ponds are �uctuant environments.Fernandez-Alaez & Fernandez-Alaez (2010) ex-

plore in temporary and permanent ponds, as well,but subject to marked seasonal �uctuations, thedrastic changes of main ions and nutrients; �rstly,after waterlessness in summer and then after re-�lling in autumn and spring. Long-standing nat-ural temporary ponds, with a long history ofa more or less predictable hydrological pattern,have evolved to start the annual wetting with ahighly structured community of relict species notfound in any other habitat type. Biodiversity, in-cluding active and diapause stages, shapes a sta-ble community that becomes active by relativelypredictable environmental pulses and that fol-lows a repetitive process where succession trendscan be tracked year after year. This view is wellexempli�ed by the study of seasonal changes, fo-cused mainly on crustaceans, in Sinarcas pond(East Spain) by Sahuquillo & Miracle (2010).This pond constitutes a true biodiversity hot spot,where communities with a high percentage of en-dangered relict or rare species are still thrivingnowadays (with respect to crustaceans, all groupsof large branchiopodes and three coexisting diap-tomids). There are not many ponds left with sucha high diversity in Europe. The same study in-dicates that the deepening of a nearby pond hasled to impoverishment and disappearance of tem-porary water specialists. Thus, it is highly rec-ommended that conservation be directed towardsmaintaining ancient natural ponds as they are,with interventions limited to regulate those activ-ities that could have impacts in its watershed and toremove human activities out of its basin, i.e. out ofall the potentially flooding land, albeit it might notreplenish to whole capacity all the years. Althoughthis land could go for long dry periods, it shouldnot be considered a waste land neither a land thatneeds restoration, but an integral part of the pond,in both its aquatic or terrestrial phase, containinga seed and egg bank of both phases.

Ecological assessment and monitoring is amajor topic in conservation that has seldom beendeveloped in ponds. As we have noticed above,they are not considered in the European WaterFramework Directive by many Member States.However conservation of ponds is a recognizedneed (Pond Manifesto) due to increasing impactsof environmental alterations as a result, for exam-

Preface 5

ple, of land use in a changing climate. The papersby Angelibert et al. (2010) and Indermuehle et al.(2010) constitute an advanced step in developinga tool based on a rigorous scienti�c frameworkbut useful for the “on the ground” practition-ers. They propose the IBEM index a simpli�ca-tion of the PLOCH assessment method (Oertliet al., 2005b), which follows the methodologyadopted by the European Water Framework Di-rective, thus the ratio to a reference state is trans-lated into one of �ve quality classes. To facil-itate the method of implementation, a website(http://campus.hesge.ch/ibem) enables the calcu-lation of the index online, and provides support tousers on both sampling and assessment method-ologies. The IBEM-Index is a rapid assessmentstandardized method which gives an overall valueof pond biodiversity and has proven to be suc-cessful in regional screenings or site monitoringin Switzerland as a good indicator of ecologi-cal quality. Standardized sampling techniques areone of the key questions to obtain good compar-ative assessment data, but it is very important toselect those that minimize the impact of samplingprocesses on the ecosystem. In this sense, it is re-markable the contribution of Scher et al. (2010)testing the invertebrate sampling ef�ciency andrepresentativeness of different and resourceful ar-ti�cial substrates. In addition to that, the workhighlights the importance of the arti�cial sub-strate type on its colonization by macroinverte-brates in lentic systems.

Ecological restoration is also one of the man-agement measures; Anton & Armengol (2010)studied different restored ponds in Albufera Nat-ural Park (Mediterranean Spain coastal area) inrelation to zooplankton diversity. One of the con-clusions is that the lapsed time since a pond isrestored is an important factor for species compo-sition and diversity; but seems to be an importantfactor mainly in the temporary systems, since thepermanent ponds are less in�uenced.

One of the more drastic restoring measures isdirected to the creation of new ponds and severalworks have indicated the success of this practice(Williams et al., 2008). In this issue, Gar-mend�a & Pedrola (2010) present a short applied

paper addressed to practitioners describing a sim-ple water balance model and its application toa hypothetical wetland pond albeit forced withreal meteorological data in an arid country. Themodel explores how pond depth and shape areimportant for determining pond hydroperiod. Thecreation of ponds or modi�cation of natural oneshas been an ancient practice to hold water fordifferent uses mainly irrigation and cattle water-ing. It has been shown that arti�cial, more or lessintensively used ponds, may sustain biodiversityat a regional scale in an agricultural landscape(Cereghino et al., 2008), this being true even inhighway stormwater detection ponds (Scher etal., 2004). Wide farm pond landscapes can befound in many agricultural areas of dry countries.In this issue, Leon et al. (2010) based on a com-parison of a large number of farm ponds in An-dalucia (Southern Spain) with the protected nat-ural wetlands of this region reinforced the sameconclusions that farm ponds are important to pre-serve biodiversity in the agricultural landscape.Species richness and diversity in farm ponds withnatural substrates reached similar levels than nat-ural wetlands. However their results show veryclearly that ponds constructed or rebuilt with ar-ti�cial substrates (plastic or concrete) had signif-icantly lower zooplankton species richness thanponds with a natural substrate.

Due to their small size, ponds are very sensi-tive to the surrounding landscape, and the land-scape indicators (Gergel et al., 2002) applied tostream ecology, such as percentage of agricul-tural land, could also be used to predict a va-riety of water chemistry parameter in ponds. Inthe present issue, there is also a contribution thathighlights the in�uence of land uses in the catch-ment area, in the water chemistry and trophic levelof ponds (Kuczynska-Kippen & Joniak, 2010).Surrounding land use might as well have an effecton the size of planktonic organisms (Basinska et al.,2010). The last mentioned paper, where the sizeof the rotifer Filinia is analyzed, shows that sizenot only varies according to land uses but also inrelation to the type of habitat in the pond wherethey are found: open waters or among emergent orsubmerged aquatic vegetation.


PERSPECTIVES

Interesting new lines of thought have been ini-tiated in pond studies, in the �rst paper of thisissue Downing (2010) argues convincingly thatponds are biogeochemicaly very active and takencollectively a large fraction of carbon sequestra-tion resides in their sediments. However, muchwork is still needed to quantify carbon and nu-trient cycling and storage to understand regionaland global budgets of greenhouse gases, at multi-ple scales of space and time. Ponds are very com-mon landscape elements which originate spatialheterogeneity and are subject to high temporalvariability. McClain et al. (2003) de�ned bio-geochemical hot spots and hot moments respec-tively as patches or episodes that show dispropor-tionately high reaction rates relative to the sur-rounding matrix or longer intervening time peri-ods and recognized that hot spot and hot momentactivity is often enhanced at terrestrial-aquatic in-terfaces. Therefore pond networks are very im-portant sites with these characteristics and theirspatial arrangements must be considered in nat-ural resources management. Over a quarter of acentury ago, Likens (1984) indicated the impor-tance to protect beyond the shore line, becauseinland waters are interconnected elements of thelandscape (surface and subterranean waters, air-shed, soils, aquatic and terrestrial organisms).Land use changes affect the hydrologic routingand associated processing of transported materi-als which may alter natural linkages and perturbpond ecology, thus conservation measures mustuse watershed-ecosystem approaches.

Hydrological variation and spatial arrange-ment of ponds is very important for aquatic andterrestrial biota as well; moreover spatial het-erogeneity and pond connectivity may increasesubstantially species richness in a metacommu-nity structure. Also individual sites, despite theirsmall size, have been recognized to be truly bio-diversity hot spots. These ponds, probably rem-nants of past larger network systems, should bepreserved as they are and conservation measureswill have to be taken in the watershed if theyare threatened by intensifying agriculture or other

land uses. Since we know that processes are log-arithmic and hysteresis occurs in the responseof aquatic ecosystems to external forcing (Shef-fer, 1998) in many sites it may be urgent toprevent further irreversible alterations. In thecase of eutrophication, a sudden shift may oc-cur after long lasting pollution; when a thresh-old is exceeded the system is transmuted toan alternative state and it will not respond todecreased pollution loads, until loads are re-duced considerably below the mentioned thresh-old. But then, the system response to cessationof pollution will not retrace the same trajec-tory to initial conditions and if losses of bio-diversity occur associated to the point of injur-ing the seed and egg bank, it will never returnto its original state. It is preferable to preservenatural sites than to have to recover degradedecosystems later. Most ponds or pond areas havesmall catchment areas that facilitate the identi-�cation of impacts, so conservation approachesincluding catchment area could be easily incor-porated. Recent projects, such as the identi�ca-tion of Important Areas for Ponds (IAP project),already started successfully in the UK (www.pondconservation.org.uk/pond hap/iap.htm) willful�l the lackof informationon these environmentsand encourage better protection at large scales ofbiodiversity and pond resources. Many ponds havebeen created or modified for farm use. There isnow a challenge to think ecologically in the futureconstruction or management of small artificialwater bodies. In agreement to recent results, to pre-serve biodiversity, constructed ponds have tomimicnatural systems. Among themore important factorsto consider are the maintenance of natural sub-strates (Boavida1999), hydrology,morphology andreduction of the contamination of inflowingwaters.

In 2010, ‘The Year of Biodiversity’, the 4thEPCN Conference will be held in Berlin (Erkner),with the theme “Eyes of the Landscape-value ofponds in the 21st century”. Its objective is tointensify exchange of experiences of pond expertsfrom both, basic sciences and applied work onconservation andmanagement to address the issuesof the Pond Manifesto (2008), as the organizersindicated in their invitation to theConference.

Preface 7

ACKNOWLEDGEMENTS

We are very grateful to the organizers of theEPCN meeting in Valencia, especially to Igna-cio Lacomba, Vicente Sancho and Benjam� Perezfor the excellent organization of a very valu-able meeting. We acknowledge the support ofthe Life-Nature project “Restoration of priorityhabitats for amphibians” (LIFE05/NAT/E/00060)and of the “Conselleria de Medi Ambient, Aigua,Urbanisme i Habitatge of the Generalitat Valen-ciana”. Thanks also to all the manuscript review-ers and to Joan Armengol (chief editor of Limnet-ica) and the “Asociacion Iberica de Limnologia”(AIL) for the publication of this special issue.

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Emerging global role of small lakes and ponds: little things mean a lot

John A. Downing∗

Ecology, Evolution & Organismal Biology, Iowa State University, Ames, IA, USA2


Received: 6/10/09 Accepted: 18/10/09

ABSTRACT

Emerging global role of small lakes and ponds: little things mean a lot

Until recently, small continental waters have been completely ignored in virtually all global processes and cycles. This hasresulted from the neglect of these systems and processes by ecologists and the assumption that ecosystems with a small arealextent cannot play a major role in global processes. Recent inventories based on modern geographical and mathematicalapproaches have shown that continental waters occupy nearly twice as much area as was previously believed. Further, theseinventories have shown that small lakes and ponds dominate the areal extent of continental waters, correcting a century-long misconception that large lakes are most important. The global importance of any ecosystem type in a process or cycleis the product of the areal extent and the intensity of the process in those ecosystems. Several analyses have shown thedisproportionately great intensity of many processes in small aquatic ecosystems, indicating that they play an unexpectedlymajor role in global cycles. Assessments of the global carbon cycle underscore the need for aquatic scientists to view theirwork on a global scale in order to respond to the Earth’s most pressing environmental problems.

Key words: Ponds, lakes, global limnology, carbon, lake size, sequestration.

RESUMEN

La emergencia del papel global de los pequenos lagos y charcas: el gran signi�cado de las pequenas cosas

Hasta muy recientemente, las aguas continentales de pequeno volumen se han ignorado completamente en todos los procesosy ciclos globales. Esto ha sido el resultado de la poca consideracion de estos ecosistemas y procesos por los ecologos yde asumir que los ecosistemas que ocupan un area pequena no juegan ningun papel importante en los procesos globales.Inventarios recientes basados en aproximaciones geogra�cas y matematicas modernas indican que las aguas continentalesocupan casi el doble del area de lo que se cre�a anteriormente. Ademas, estos inventarios han mostrado que las charcas y la-gunas de pequenas dimensiones predominan en la extension super�cial de las aguas continentales, corrigiendo la concepcionequivocada de todo un siglo de que los grandes lagos eran los mas importantes. La importancia global de cualquier tipode ecosistema en un proceso o ciclo es el producto de su super�cie por la intensidad del proceso en el ecosistema. Diversosanalisis han mostrado la intensidad desproporcionadamente grande de muchos procesos en los pequenos sistemas acuaticos,indicando su sorprendente papel primordial en los ciclos globales. Evaluaciones del ciclo global del carbono ponen de man-i�esto la necesidad de que los ecologos acuaticos tengan una vision de su trabajo a escala global, para poder responder alos problemas ambientales mas preocupantes.

Palabras clave: Charcas, lagos, limnolog�a global, tamano de los lagos, secuestro de carbono.

INTRODUCTION

Ever since Halbfass (1914) and Thienemann’s(1925) work cataloguing the lakes of the world,

science has assumed that the world’s large lakescover the most area and therefore are the mostimportant to study (Downing et al. 2006, Down-ing & Duarte 2009). In spite of this long-standing

10 J. A. Downing

error of scienti�c reasoning (Downing 2009), ourcommon, human experiences tell us that smallthings in life, society, or nature can be moreimportant than their sizes imply. For example,part of the title of this article (“Little thingsmean a lot. . . ”) comes from song lyrics by EdithLindeman (no relation to Raymond) express-ing that the tiny gestures people make have themost value. The 19th Swiss philosopher and poet,Henri-Frederic Amiel, suggested that “What wecall little things are merely the causes of greatthings” (Amiel 1893). Bruce Fairchild Barton,the American publicist, politician, and authorwrote, “Sometimes when I consider what tremen-dous consequences come from little things... I amtempted to think there are no little things” (Bar-ton 1917). The 18th century German scientist,satirist, and philosopher, Georg Christoph Licht-enberg, noted that “the tendency of people toconsider small things as important has producedmany great things” (Friederici 1978). We shouldnot be misled by their small relative size into as-suming that small lakes and ponds are unimpor-tant. In A Case of Identity (Conan Doyle 1920),Sir Arthur Conan Doyle (speaking as SherlockHolmes) suggested, “It has long been an axiom ofmine that the little things are in�nitely the mostimportant.” Human experience suggests that weshould expect the small parts of aquatic ecosys-tems, e.g., small lakes, ponds, puddles, marshes,and streams, to be of disproportionately great im-portance in world cycles and processes.

Lakes, especially small ones, are ignoredglobally

Globally, lakes and ponds are generally ignoredas being insigni�cant or are thought of only asreservoirs where water and materials are held fora short time before delivery to streams, rivers,and the oceans. Terrestrial ecologists, climatolo-gists, and oceanographers tend to think of con-tinental waters as “plumbing” that delivers ortransports water, with little processing. Recently,this has been shown to be an incorrect assump-tion (Cole et al. 2007, Downing 2009, Tranviket al. 2009). Further, scientists studying lenticwaters have long known that they process glob-

Figure 1. Frequency analysis of use of “lake” or “lakes” ver-sus “pond” or “ponds” in the title of scienti�c publications in-dexed by the Web of Science over the last century. Absolutefrequency is dependent on the literature indexed by Web of Sci-ence and the completeness of index coverage. Analisis de fre-cuencias de la utilizacion de la palabra “lake” o “lakes” versus“pond” o “ponds” en los t�tulos de las publicaciones cient��casindexadas en la Web of Science durante el siglo pasado. Lasfrecuencias absolutas dependen de la bibliograf�a indexada yla cobertura de dicho �ndice.

ally important materials. The concepts of nutri-ent and material retention and spiraling have beenrudiments of limnology for several decades.

The study of small aquatic systems has laggedbehind larger-lake limnology over much of thepast century. An analysis of publications on“ponds” versus “lakes” in the publications in-dexed by Web of Science (Fig. 1) suggests thebias of ecologists and limnologists toward study-ing larger water bodies as well as the differentialrates of growth of publications in these areas (seealso Oertli et al. 2009). This analysis shows thatstudies titled as pond studies constitute only about25% of the aquatic publications indexed in anygiven year. Further, although the rate of growthin the publication of pond studies increased at anaverage 19%per year from1940-1980, lake studiesincreased extremely rapidly during the boomyears of eutrophication remediation. Publicationsentitled as pond or lake studies have deceleratedin the past decade, with rates of growth in pondanalyses decelerating more than those of lakes.

Global role of small lakes and ponds 11

Table 1. Analyses of global cycles and processes completely omitting any reference to ponds or small lakes. Analisis de ciclos yprocesos globales omitiendo totalmente cualquier referencia a charcas o lagunas.

Cycle or budget Reference

Carbon (Goody &Walker 1972, Bolin 1983, Schimel et al. 1995, Intergovernmental Panel on Climate Change 2001,United States Climate Change Science Program 2003)

Energy/Radiation (Christopherson 1994, Kiehl & Trenberth 1997, Hermann 2006)

Greenhouse gases CO2: (Thorneloe et al. 2002)

CH4: (Weissert 2000)

N2O: (Seinfeld & Pandis 1998)

Nitrogen (Rosswall 1983, Chameides & Perdue 1997, Bin-le et al. 2000, Roy et al. 2003, Raven et al. 2004)

Oxygen (Cloud & Gibor 1970, Goody & Walker 1972, Walker 1980, Keeling et al. 1993)

Phosphorus (Graham & Duce 1979, Richey 1983, Lerman 1988)

Silicon (Goody & Walker 1972, Nelson et al. 1995, Treguer et al. 1995)

Sulphur (Freney et al. 1983, Raven et al. 2004)

Water (Clarke 1991, Hinrichsen et al. 1998, Winter et al. 1998)

That small aquatic ecosystems are currently per-ceived as irrelevant to global problems is, how-ever, undeniable. One needs only to look atschematic diagrams of various global materialcycles to see that limnology and aquatic ecologyhave been left behind. Nowhere is this more ob-vious than in global analyses of the carbon cy-cle (e.g., Schimel et al. 1995). All continentalwaters are frequently absent from these globalviews. The carbon they store and any process-ing of this material they do (e.g., burial, emis-sion) are completely omitted. Small, continentalaquatic ecosystems are ignored in virtually allglobal views and processes (Table 1).

Lakes, ponds, rivers, and streams are of globalimportance

Although they have been ignored, limnologistsknow that our systems are significant in global cy-cles.Nowhere is failing to consider themmore seri-ous than in the global carbon budget. Accuracy ofestimation of the global carbon budget is critical be-cause it will determine how effectively society canrespond to the challenge of global climate change.

A few years ago, some of us attempted to in-tegrated fragmentary knowledge on the role ofinland waters into the global Carbon (C) cycle

(Downing et al. 2006, Cole et al. 2007). The in-formation available at the time indicated that, farfrom being neutral conduits of C from lands tothe sea, inland waters process large amounts ofcarbon buried in freshwater ecosystems or de-gassed to the atmosphere. Since that time, wehave learned that the �rst calculations underes-timated the area covered by virtually every cat-egory of inland waters (Downing et al. 2006,Downing 2009, Downing & Duarte 2009). Thoseestimates demonstrated that inland waters mayprocess about 1 Pg/y (petagram/year) more Cthan was previously thought to be delivered tothem. This was more than double the amountback-calculated as the landscape’s contribution torivers and the sea through the supposedly neu-tral conduit of inland waters. These numbers arebeing revised upward quite rapidly (e.g., Tran-vik et al. 2009) and now show a very activeprocessing of C by aquatic ecosystems (Fig. 2).Traditional analyses have calculated the loss ofC from the landscape simply as the amount de-livered to the sea by rivers but these calcu-lations have ignored the role of inland watersin emitting and burying C.

Cole et al.’s (2007) calculations are beingrapidly revised upward, underscoring the needfor limnologists to engage in global limnology

12 J. A. Downing

Figure 2. Illustration of the quantitative and qualitative differ-ences between the “neutral pipe” model suggesting the inlandwaters transport carbon without processing it, and the “activepipe” model (Cole et al. 2007) in which preliminary estimatesof the global burial of C by aquatic ecosystems and the evasionof CO2 by aquatic ecosystems is admitted. The original view ofthese models has been revised to re�ect more recent data (Tran-vik et al. 2009). This revision suggested that the large burialand evasion of carbon by aquatic ecosystems requires that ex-port from land is almost three-times greater than previously be-lieved. (Pg/y = 1015 grams/year). Esquema de las diferenciascuantitativas y cualitativas entre el modelo de “conducto neu-tro” en donde las aguas continentales transportan el carbonosin procesarlo y el modelo de “conducto activo” (Cole et al.2007) en el cual se admite el entierro global de C y la liberacionde CO2 por los ecosistemas acuaticos. El esquema original deestos modelos se ha revisado para re�ejar los datos mas re-cientes (Tranvik et al. 2009). Esta revision sugiere que el promi-nente entierro y liberacion de C por los ecosistemas acuaticos,requiere que se exporte desde las zonas terrestres una cantidadcasi tres veces mayor de lo que anteriormente se cre�a.

(Downing 2009). This lacuna is very obviousconsidering the under-emphasis of the globalrole of small aquatic ecosystems. The formerview that Earth’s important compartments areocean, atmosphere, and land, connected toge-ther by the assumed neutral pipes and conduitsprovided by large lakes and rivers was a majorerror. An accurate understanding of global cy-cles requires seeing the biosphere as a networkof inter-connected metabolically active sites, in-cluding small lakes and ponds.

Why might small lakes and ponds be veryimportant?

It has recently been suggested that the global im-portance of any set of ecosystems is determinedby the product of the amount of the biospherethey constitute and the intensity of the processof interest within them (Downing 2009). Down-ing (2009) also explored ways of “scaling-up”measurements made in small lakes and ponds forevaluating their global role. The global role ofsmall lakes and ponds has been doubly missedin the past because the spatial extent of lakes hasbeen underestimated as well as the fraction of theworld’s lakes that are small (Lehner & Doll 2004,Downing et al. 2006).

An early inventory of the world’s lakes was�rst published in 1914 (Halbfass 1914) andwas expanded to include August Thienemann’sanalysis of the lakes of Europe (Thienemann1925). At that time, Thienemann (1925) sug-gested that around 2.5 million km2 or about 1.8 %of the land surface, is covered with lakes andponds, and that global lake area is dominated by afew very large lakes (Downing 2009). This view-point was fundamentally unchanged for about 70years (Schuiling 1977, Herdendorf 1984, Mey-beck 1995, Kalff 2001) except that Robert Wetzel(1990) felt that the world’s lake area is dominatedby small lakes and ponds (Downing et al. 2006).

Lehner and Doll (2004) performed a fullinventory of world lakes by using GIS of satelliteimagery to count all of the world’s moderatelysized to large lakes, but could not count smalllakes and ponds (≤ 0.1 km2).Their datasuggesteda Pareto distribution (Pareto 1897, Vidondo etal. 1997) that appears to �t lake-size distribu-tions down to 0.001 km2 (Downing et al. 2006).A similar relationship was also found to �t theabundance and size-distribution of the world’sconstructed lakes and analyses of regional datashowed that constructed farm ponds bore a con-sistent relationship to agricultural land area andprecipitation (Downing et al. 2006). These re-sults suggest that there are 304 million naturallakes in the world and they cover about 4.2 mil-lion km2. This area is nearly twice that assumedby several others (Schlesinger 1997, Kalff 2001,


Figure 3. Global size distributions of numbers and land areacovered by natural and constructed lakes. Data are re-plottedfrom the original publication (Downing et al. 2006). The �g-ure shows that size distribution of natural lakes and constructedlakes are similar and that global lake area is dominated bysmall lakes, not large ones as 20th century analyses suggested(Halbfass 1914, Thienemann 1925, Schuiling 1977, Herden-dorf 1984, Meybeck 1995). Distribucion global del numero ysuper�cie de los lagos construidos y naturales. Datos repro-ducidos de la publicacion original (Downing et al. 2006). La�gura muestra que el tamano de los lagos naturales y los cons-truidos es similar y que el area global esta dominada por loslagos pequenos y no por los grandes como suger�an los analisisefectuados en el siglo XX.

Wetzel 2001, Shiklomanov &Rodda 2003) and thearea is more strongly dominated by small lakes andponds (Fig. 3) than past analyses have suggested.

How small are the smallest lakes and how longdo they last?

Many pond ecologists work on water bodies evensmaller than the lowest interval on �gure 3. If one

uses the Pareto distribution to project the num-ber of water bodies on Earth in the range of0.0001-0.001 km2 (100-1000 m2), the result ac-centuates the dominance of small water bodieson continents. It is likely that there are about3.2× 109 natural ponds in this size-range andthey have an area of around 0.8 billion km2.Whether these ecosystems are permanentlyaquatic or become semi-terrestrial at certaintimes of the year, or whether they wax and waneover the course of geological time is not fullyknown. Our ability to catalog and map small fea-tures is, as yet, new, and we will learn how thesesmall landscape features contribute to the inter-face of terrestrial and aquatic ecology.

Most of the Pareto distributions we have ana-lyzed (Downing et al. 2006) had some curvaturetoward the small sizes of lakes, implying that theyhad been underestimated in inventories, removedfrom the landscape through erosion, deposition,and landscape alteration, or both. It seems quitelikely that the residence time of small water bodieson a landscape may be low enough that some smallsystems disappear over time or are replaced by pro-cesses of pond formation. Some may be essentiallyhydric soils for part of the year. Any alteration ofthe land surface, including the filling of depressionscan result in new small depressions that accu-mulate water and generate an aquatic ecosystem.

The intensive activity of small aquatic ecosys-tems and their dimensions make them more dy-namic in time than large water bodies. I know,for example, of many small ponds that I knew asa child that are no longer part of the aquatic land-scape. Likewise, however, I know of many mod-ern small ponds that did not exist a few decadesago. One can estimate the relationship betweenthe sizes of lakes or ponds and their likely life-spans following some assumptions about dimen-sions and morphometry. If the mean depth (m)of a lake is assumed to be 12.1

√L′, where L′ is

the average of effective length and breadth (km)(Gorham 1958, Stra�skraba 1980), �gure 4 showsthe likely life-span of these lakes and ponds, as-suming that lakes are elliptical in shape withlength about double the breadth.

If sediment deposition is around 1 mm/y thenvery small lakes and ponds (< 0.01 km2) will

14 J. A. Downing

Figure 4. Potential life-time of aquatic ecosystems of a rangeof sizes. The calculations were based on assumed rates of sedi-mentation spanning the range of those observed in oligotrophicto eutrophic lakes and the assumptions that the mean depth (m)of a lake is around 12.1

√L′, where L′ is the average of effec-

tive length and breadth (km) (Gorham 1958, Stra�skraba 1980),and length is approximately double the breadth. Duracion po-tencial de los ecosistemas acuaticos de diferentes tamanos. Loscalculos se han basado en las diferentes tasas de sedimentacionestimadas de las observadas en lagos, desde oligotro�cos aeutro�cos, y en el supuesto de que la profundidad media (m) deun lago ser�a 12.1

√L′, en donde L′ es la media de la longitud y

anchura efectivas (Gorham 1958, Stra�skraba 1980), siendo lalongitud aproximadamente el doble de la anchura.

have lifetimes of <1000 y. In even more oligotro-phic landscapes where sediment deposition ratesare < 1 mm/y, small lakes and ponds might take1000-10,000 y to disappear. In highly erodible,nutrient-enriched environments, however, sub-stantially sized small lakes and ponds may disap-pear in a few decades through �lling and succes-sion. This temporal dynamic is a unique featureof the limnology of small lakes and ponds andaccentuates our need to understand their functionas well as their succession and origination.

Ponds and small lakes play an active globalrole

The global importance of any ecosystem type isdetermined by the product of the aerial extent ofthat ecosystem across the Earth and the intensityof processes in them, relative to other ecosys-tem types (Downing 2009). Indeed, the global

dominance of limnological processing only re-quires that these processes be more than 33-timesgreater (on an areal basis) in lakes than in ter-restrial environments and more than 115-timesgreater than in the world’s oceans. If globally im-portant rates and processes are the same in small(≤ 1 km2) lakes and ponds as they are in largerones, small lakes and ponds constitute at leasta third of the processing by aquatic ecosystemson the planet (Fig. 3). For small lakes and pondsto dominate inland aquatic processing, rates andprocesses in small systems need only be doublethose seen in larger ones. Knowledge of the “in-tensity” of processes is an important need in or-der to participate in global science.

Many aquatic rates, processes, and quantitiesare more intense, complex, or abundant in pondsand small lakes than in larger lakes. The bioticcomplexity and richness of small aquatic systemsis well-known. For example, macrophyte cover-age is greater in smaller lakes (Duarte et al. 1986)leading to enhanced production and habitat com-position. In the pelagic zone, too, small lakeshave more complex thermal structure than largeones (Xenopoulos & Schindler 2001).

Small lakes and ponds are important to themaintenance of regional biodiversity and stabil-ity. Small lakes have greater waterfowl speciesrichness per unit area than large lakes (Elmberget al. 1994). Small lakes and ponds promoteenhanced regional biodiversity in aquatic birds,plants, amphibians and invertebrates because oflow �sh biomass and high richness and abun-dance of aquatic plants (Scheffer et al. 2006).Smaller lakes have a greater proportion of smallnon-game �sh species such as the Cyprinidae(Matuszek et al. 1990); small non-game �sh areoften overlooked by �sh management. Biomasssize spectra show more negative coef�cients insmall lakes indicating a greater dominance ofsmall, active organisms (Cyr & Peters 1996). Fig-ure 5 shows data on biodiversity in well-studiedlakes analyzed by Dodson et al. (2000). The dataindicate that small lakes contain many morespecies of virtually all taxa, per unit area, than dolarge lakes. Although no particular meaning shouldbe attributed to the existence of such a correla-tion (km2 appears in both axes), even moderate


Figure 5. Species-richness per unit area of various aquatictaxa in lakes of different sizes (Data from Dodson et al. 2000).If individual lakes in the same region have slightly differentcommunity structure, the �gure implies that small systems en-hance regional biodiversity. Riqueza de especies por unidad desuper�cie de varios grupos taxonomicos en lagos de diferentetamano (Datos de Dodson et al. 2000). Si los lagos individua-les de una region tienen comunidades ligeramente diferentes, la�gura indica que los sistemas pequenos aumentan la biodiver-sidad regional.

differences in community structure among smalllakes and ponds suggest that higher regional biodi-versity canbemaintainedby100km2 of small lakesthanwould be contributed by a single 100km2 lake.This, plus the preference of recreational boatersfor large lakes (Reed Andersen et al. 2000), mayhelp explain why small lakes are known to bemore resistant to invasion by exotic and nuisancespecies than are large ones (Win�eld et al. 1998).

Small lakes and ponds are also known for highproductivity. Fish productivity generally declineswith increasing lake size, indicating that small-est lakes have highest production per unit area,often by several orders of magnitude (Rounsefell1946, Hayes & Anthony 1964, Youngs & Heim-buch 1982, Downing et al. 1990) (Fig. 6). Lakesize appears to act on biomass and �sh-size distri-bution because after the effects of body mass andbiomass are accounted for, �sh production (perunit area) may be higher in larger lakes (Downing& Plante 1993). Small lakes and ponds can be sub-stantially more biologically active than large lakes.

Figure 6. Fish yield and lake-size data summarized byYoungs & Heimbuch (1982) from other sources (Ryder 1965,Oglesby 1977, Matuszek 1978). The solid line is a least-squaresregression of the data showing the average trend in productionwith lake size (r2 = 0.39, n = 27). Produccion pesquera enrelacion con el tamano del lago. Datos recogidos por Youngs& Heimbuch (1982) de diversas fuentes (Ryder 1965, Oglesby1977, Matuszek 1978). La l�nea solida representa la regresionpor m�nimos cuadrados, mostrando la relacion de la pro-duccion con el tamano del lago (r2 = 0.39, n = 27).

Carbon-processing is intense in small lakesand ponds

Information is beginning to emerge showing thatcarbon processing intensity is very great in smallwater bodies. Stable isotope analyses indicatethat smaller lakes and ponds may be more het-erotrophic than large ones, processing substan-tial amounts of terrestrial or external carbon (Post2002). Dissolved organic carbon concentrationsare therefore signi�cantly negatively correlatedwith lake size (Xenopoulos et al. 2003). SurfaceCO2 concentrations are much higher in smallerlakes than large ones (Kelly et al. 2001). In an-other large data set taken from across Finland,CO2 concentrations and aerial CO2 evasion de-clined sharply with increasing lake size (Korte-lainen et al. 2006). Oxygen concentrations tendto be lower in ponds and small lakes than inlarger ones (Crisman et al. 1998), enhancinggreenhouse gas (GHG) emissions and carbon se-questration. Potential methane emission is much

16 J. A. Downing

Figure 7. Measured methane concentrations in lakes fromaround the world related to the sizes of lakes. Data are fromBastviken et al. (2004). Concentraciones de metano en lagosde diferentes partes del mundo, en relacion con el tamano delos lagos. (Datos de Bastviken et al. 2004).

greater in small lakes than large ones (Michmer-huizen et al. 1996). Using a data compilationfrom around the world, Bastviken et al. (2004)showed that concentrations of methane, and per-haps therefore losses to the atmosphere, aregreatest in small lakes and ponds (Fig. 7). Lowoxygen concentrations in small lakes (Crisman etal. 1998) and the relationship between low oxy-gen and elevated N2O (Knowles et al. 1981) sug-gest that N2O emissions from ponds and smalllakes can be much higher than those of largerlakes. Rates of organic carbon sequestration perunit area in the sediments of small lakes has beensuggested to be at least an order of magnitudehigher than that of larger lakes (Dean & Gorham1998, Stallard 1998, Downing et al. 2008).

Pond size, eutrophication, and carbonsequestration: some examples

The global importance of an aquatic process orquantity depends, to some degree, upon the ex-tent of the ecosystem type in the biosphere. Like-wise, seemingly unimportant ecosystems, eventhose that cover only a small area of the land sur-

face, can be important globally if the intensityof a process is extremely high. Even the small-est ponds are very abundant on Earth. A conser-vative estimate is that small agricultural pondscover about 77,000 km2 worldwide (Downing etal. 2006, Downing & Duarte 2009). Farm pondsand tanks appear to be increasing at rates from0.7 % per year to 60 % per year in various re-gions as increasing pressure is put on agriculturallands to provide food for growing populations.

Previous analyses of roles of constructedlakes in important global rates like organic Cburial (e.g., Cole et al. 2007) have calculatedglobal deposition and carbon content of sedimentsderived mostly from large water bodies (Dendy& Champion 1978, Mulholland & Elwood 1982,Dean & Gorham 1998, Stallard 1998). Becausethese data seemed limited and ignored the activeand abundant small lakes and ponds on Earth, werecently used repeated bathymetric analyses anddirect measures of sediment characteristics to es-timate the likely rate of burial of organic C inthe sediments of eutrophic lakes and impound-ments (Downing et al. 2008). In the 40 lakeswe studied (triangles, Fig. 8), we found that sedi-ment organic carbon burial rates were higher thanthose assumed for fertile impoundments by pre-vious studies and were much higher than thosemeasured in natural lakes. Organic carbon burialranged from a high of 17 kg C/m2/y to a lowof 148 g C/m2/y and was signi�cantly greater insmall impoundments than large ones (Fig. 8).

These analyses suggest that median organic Csequestration in moderate to large impoundmentsmay be double the rate assumed in previous anal-yses and exceeds rates of carbon sequestrationfound in any ecosystem in the world. Medianareal C burial rates in these lakes were 10-timesthose seen in wetlands, 100-times those docu-mented in tropical forests, 1000-times those as-sessed in tropical and boreal forests, and 10,000-times those estimated for the world’s oceans. Ex-trapolation suggests that each year, Earth’s cur-rent moderately sized impoundments may bury4-times as much C as the world’s oceans. Theworld’s farm ponds alone seem likely to sequestermore organic carbon each year than the oceans and33%asmuch as theworld’s rivers deliver to the sea.


Figure 8. Sediment organic carbon burial rates compared among types of aquatic and terrestrial ecosystems. Data on oligotrophicand eutrophic lakes and impoundments in Asia, the United States, central Europe, and Africa are fromMullholland & Elwood (1982).Data from Downing et al. (2008) are for lakes in an agriculturally eutrophic region of the Midwest United States; the solid line showsa least squares regression of these data. Observations made by Biggs (2008) are for small ponds in the United Kingdom. Data fromSobek et al. (2009) include a variety of lakes worldwide, including Lake Baikal at the extreme right of the graph. Terrestrial data arefrom Schlesinger (1997) and data on marine vegetated areas are from Duarte et al. (2005). Carbon burial in the world’s oceans werecalculated after Sarmiento & Sundquist (1992) assuming the world’s oceans have an area of 361 million km2. Arrows at right indicatemedian levels of carbon sequestration in diverse ecosystem types. Comparacion de las tasas de entierro de carbono en diferentestipos de ecosistemas acuaticos y terrestres. Los datos de lagos y embalses oligitro�cos y eutro�cos de Asia, Estados Unidos, EuropaCentral y Africa proceden de Mullholland & Elwood (1982). Los datos de Downing et al. (2008) correponden a lagos en una regionagr�cola y eutro�ca del Oeste Medio de Estados Unidos y la linea solida representa la regresion por m�nimos cuadrados de estosdatos. Las observaciones de Biggs (2008) corresponden a pequenas charcas del Reino Unido. Los datos de Sobek et al. (2009)incluyen una variedad de lagos de todo el mundo, con el lago Baikal en el extremo derecho del gra�co. Los datos terrestres son deSchlesinger (1997) y los de areas marinas vegetadas de Duarte et al. (2005). El entierro de carbono en los oceanos se ha calculadode acuerdo con Sarmiento & Sundquist (1992) asumiendo que los oceanos ocupan una super�cie 361 millones de km2. Las �echasde la derecha indican la mediana de los niveles de secuestro de carbono en diversos tipos ecosistemas.

Eutrophication and landscape alteration may playimportant roles in determining C burial in lakes.C burial rates in eutrophic lakes are nearly an or-der of magnitude higher than those found in olig-otrophic lakes of similar size (Fig. 8). Small lakesin agricultural regions (Downing et al. 2008)have very high rates of burial but are in thesame range as the small UK ponds, impound-ments around the world, and lakes with high sed-iment loads. For example, Lake Wohlen (Sobeket al. 2009), a mesotrophic, short water residencetime (2 days) impoundment in the Aare Riverhas C sequestration rates of 570-1140 g C/m2/y.Therefore, it appears that extremely high ratesof C burial are typical of small lakes, lakes withhigh rates of primary production due to eutroph-

ication, and lakes receiving substantial loads ofriverine or watershed-derived organic sediments.Small lakes and ponds make up around a third ofthe area of continental waters but have rates of Cburial that exceed those of larger lakes by an orderof magnitude or more. It is likely, therefore, thatcarbon sequestration by the world’s small lakesand ponds dominates carbon burial by aquaticecosystems. Because aquatic ecosystems seem toprovide substantial carbon burial worldwide, pondsand small lakes may be the most important sitesin the biosphere for organic carbon sequestration.

These �ndings should not be misconstrued tosuggest that small lakes and ponds are perfectsinks for excess carbon. Small oligotrophic lakesmay evade substantial allochthonous C as CO2

18 J. A. Downing

(Kelly et al. 2001, Kortelainen et al. 2006). Smalllakes and ponds can be quite eutrophic so CH4

and N2O release may be substantial (Knowles etal. 1981, Michmerhuizen et al. 1996, Bastvikenet al. 2004), exacerbating atmospheric problems.This analysis suggests, however, that an accurateview of the global carbon budget will be elu-sive unless small lakes and ponds are analyzed,understood, and considered.

Global research needs for small aquaticecosystems

Global understanding of the role of small lakesand ponds in processes throughout the biosphererequires inventories of water bodies and knowl-edge of the important rates and processes theymediate (Downing 2009). There are three impor-tant steps. (1)We need to identify patternsin glob-ally important quantities, rates, and processes, andunderstand how they covary with lake and pondcharacteristics. (2) We need to create scaling rulesfor these quantities, rates, and processes that willpermit meaningful up-scaling to a global level.(3) Because society depends upon reliable globalscience, we need to derive numerical and statisticalmethods to ensure that global calculations areaccurate and precise enough to be comparableto other global estimates. Accomplishment ofthese tasks will advance us substantially towardestimating human- and climate-mediated effectson the global role of small aquatic ecosystems.

Many variables are in need of global scaling.For example, understanding the conversions ofcarbon in small lakes and ponds is of very highpriority, in order to contribute substantially todiscussions of global climate change. Likewise,understanding of patterns in nutrients in thesewater bodies, as well as �uxes and conversionsof important gasses (e.g., N2O, NHx) and met-als (e.g., Hg), will improve global understandingof the role of small water bodies in global nu-trient, gas, and toxin budgets. Remarkably, smalllakes and ponds have not yet been integratedinto global heat and water budgets so recognitionof patterns in water and energy �uxes amongstaquatic systems is also important. Small aquaticecosystems are disproportionately important sites

for the production of food so it is important toevaluate global patterns in production.

We need to quantify and understand the roleof small water bodies in the functioning of thebiosphere. We do this by asking whether thequantity or process is large or small with respectto other types of ecosystems and whether we canmake an estimate of that quantity or process thatis well enough constrained to be reliable. Thesequestions cause us to ascertain whether the pro-cess is likely great enough to justify a more ac-curate and precise answer and how likely weare to be able to de�ne the answer more pre-cisely. Therefore, much of this task is makingestimates of biosphere-level rates and processesattributable to small lakes and ponds, compar-ing these to estimates made for other ecosys-tems, and re�ning and improving our estimatesto yield more accurate and precise assessmentsof the global role of small aquatic systems.

CONCLUSIONS

Recently, limnologists and aquatic ecologistshave discovered that aquatic ecosystems aremuch more plentiful in the biosphere than hadbeen believed. This is especially true for smalllakes and ponds because new analyses showthat they cover as much or more area as largelakes. Because historical inventories underesti-mated the areal extent of small water bodies,limnologists have spent relatively little effortstudying them so their importance to global andbiosphere processes has been under-appreciated.Emerging studies now show that ponds and smalllakes are more active in nearly every process thanlarge lakes, terrestrial, and marine ecosystems.The large area covered by small aquatic systemsand the intensity of activity mean that they maybe among the most important ecosystems in theworld. Considering the global carbon cycle, forexample, ponds and small lakes sequester car-bon at rates that are orders-of-magnitude greaterthan virtually all other global ecosystems. Thiscompensates for the small area they cover rel-ative to terrestrial and marine ecosystems, sug-gesting that carbon sequestration by ponds may


be as great as or greater than that of forests, grass-lands, and all the world’s oceans.There are severalknowledge gaps, however, including informationongas evasion and several other factors, so an activeresearch agenda on small lakes and ponds is neededto bring them into the arena of global limnologyand ecology. Work in such a high-priority arenais important to our science and careers butespecially to understanding the role of small aquaticsystems in the biosphere. Preliminary informationsuggests that they may be amongst Earth’s mostimportant and active environments.

ACKNOWLEDGEMENTS

I am grateful to the European Pond ConservationNetwork 2008 organizing committee for invit-ing me to address this important topic. I amalso grateful to the NCEAS-ITAC group (authorsof Downing et al. 2006, Cole et al. 2007), foradvancing many of the subjects presented here.This work grew out of the ITAC Working Groupsupported by the National Center for EcologicalAnalysis and Synthesis, a Center funded by NSF(Grant DEB-94-21535), the University of Cali-fornia at Santa Barbara, and the State of Califor-nia. This work was partially completed while Iwas on a sabbatical leave at Instituto Mediterra-neo de Estudios Avanzados, Esporles, Mallorca,Islas Baleares, Spain, with the generous sponsor-ship of the Consejo Superior de InvestigacionesCient��cas of Spain. Other support was providedby the Wabana Lake Research Station.

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Pools ‘on the rocks’: freshwater rock pools as model system inecological and evolutionary research

Luc Brendonck1,∗, Merlijn Jocque1,2, Ann Hulsmans1 and Bram Vanschoenwinkel1

1 K.U.Leuven, Laboratory of Aquatic Ecology and Evolutionary Biology, Ch. Deberiotstraat 32, B-3000 Leuven,Belgium.2 Central Laboratory of General Ecology, Bulgarian Academy of Sciences, 2 Yuri Gagarin Street, 1113 So�a,Bulgaria.2



ABSTRACT

Pools ‘on the rocks’: freshwater rock pools as model system in ecological and evolutionary research

Rock pools inarguably exhibit a number of characteristics which make them attractive as a model system in ecological andevolutionary research. They are usually small, pristine, clearly delineated and structurally simple systems that occur on aglobal scale. They facilitate the quanti�cation of important population and community structuring processes which are oftenhard or impossible to quantify in larger more complex systems. Basic properties and spatial con�guration of rock pools alsoclosely resemble theoretical metapopulation and metacommunity models. Due to the simple morphometry of rock pool basinsand the lack of any groundwater interactions, rock pool hydrologies are simple allowing to reliably reconstruct the disturbanceregime against which patterns of variation in life histories, population genetics, species diversity and community structure canbe interpreted.

Key words: Rock pools, temporary waters, model system, evolutionary ecology, metacommunity ecology, metapopulationbiology.

RESUMEN

Pozas en las rocas: Un sistema modelo para investigaciones evolutivo-ecologicas

Sin lugar a dudas las pozas en rocas presentan numerosas caracter�sticas que las hacen atractivas para su uso como sistemamodelo en la investigacion evolutivo-ecologica. Normalmente son sistemas v�rgenes de pequeno tamano, estructuralmentesencillos y claramente delineados, que se encuentran a escala global. Permiten la cuanti�cacion de importantes procesosestructuradores de poblaciones y comunidades que, a menudo, son muy dif�ciles o imposibles de cuanti�car en sistemasmayores mas complejos. Las propiedades basicas y la con�guracion espacial de las pozas en rocas tambien muestran unaestrecha semejanza con los modelos teoricos de metapoblacion y metacomunidad. Debido a la morfometr�a simple de lascubetas de estas pozas y a la carencia de interacciones con las aguas subterraneas, las hidrolog�as de estas pozas son depoca complejidad, lo que permite reconstruir con �abilidad el regimen de perturbacion determinante de los patronesde variacion de los ciclos de vida de los organismos, de la genetica de poblaciones, diversidad de especies y estructura decomunidades.

Palabras clave: Pozas en rocas, aguas temporales, sistema modelo, ecolog�a evolutiva, ecolog�a de metacomunidades, bio-log�a de metapoblaciones.

26 Brendonck et al.

INTRODUCTION

Advances in research are best attained with theuse of “model systems”: study subjects that areselected for intensive multidisciplinary study ba-sed on speci�c advantages they offer. The combi-ned efforts result in an accelerated understandingof processes and are probably the most ef�cientway to get a holistic understanding of life. Ty-pically model systems are organisms such as thezebra�sh Danio rerio, the �our beetle Triboliumsp., the water�ea Daphnia, etc. Surprisingly, un-til now, no habitat is generally accepted as modelsystem. The main dif�culty here lies in the limi-ted geographic occurrence of most candidate ha-bitats (e.g. bromeliads) or the high environmen-tal variability on different continents limiting thecomparability of results (e.g. ponds).

There is, however, a need for a model habitatas study system which allows for testing of ge-neral processes in a simpli�ed, but realistic set-ting. The potentials of small aquatic systems suchas ponds and pools for studies in ecology, bio-geography and evolutionary biology have beenunderlined in several key publications (Blaustein& Schwartz, 2001; Srivastava et al., 2004; DeMeester et al., 2005). Especially the fact that theyare small and manageable, easy to sample andusually occur in large numbers along importantecological gradients such as latitude, altitude, nu-trient loading and connectivity has contributed tothe popularity of their use as study systems.

The increasing awareness that a large num-ber of species today occur as discrete popula-tions arranged in a matrix of unsuitable habitathas stimulated increasingly more researchers touse insular habitat systems to study the effects ofdispersal and the spatial con�guration of habitatpatches on characteristics of populations (gene-tic diversity, population turnover; metapopulationecology) and communities (diversity, commu-nity assembly, stability; metacommunity eco-logy) (Gilpin & Hanski 1991; Wilson 1992; Lei-bold et al., 2004). Species coexistence patterns inmetacommunities are expected to be dominantlyaffected by dispersal rates (Mouquet & Loreau,2002, 2003) and patch disturbance regimes (Ost-man et al., 2006; Hughes et al., 2007). Empiri-

cal support for the different developed theoreticalmodels and metacommunity paradigms is, howe-ver, still relatively scant (Leibold et al., 2004;Holyoak & Loreau, 2006; Urban et al., 2008).

Natural aquatic ‘micro-and mesocosms’, suchas pitcher plants, tree holes and rock pools pro-vide suitable settings to test metapopulation andmetacommunity theory as they occur as discreteunits along gradients of isolation and connecti-vity (e.g. Ellis et al., 2006; Vanschoenwinkel etal., 2007; Ng et al., 2009; Pandit et al., 2009).Temporary rock pools share the advantages ofsmall size, replication and manipulability (Blaus-tein & Schwartz 2001) with other small water bo-dies but have the additional bene�t that they aremuch older systems and house more diverse com-munities (Jocque et al., 2006). Besides the factthat isolation of rock pools can easily bemeasuredthey also have the additional advantage that patchdisturbance regime is primarily determined by thehydroregime of the pools, which can easily bequantified using simple hydrologicalmodels (Huls-mans et al., 2008; Vanschoenwinkel et al., 2009a).

Freshwater rock pool ecosystems include alltypes of depressions occurring on rocky substra-tes which (periodically) hold freshwater (Fig. 1).Most of these habitats rely on precipitation for�lling, while others may be fed by �ooding ri-vers or ground water (e.g. quarry ponds). Here weonly focus on the typical rain fed rock pools whichhouse specialized communities adapted to the oftenunpredictable patterns of drying and flooding.

In the light of the increasing search for anappropriate model system for (meta) communityecology we here discuss the potential of freshwa-ter rock pools to �ll this lacuna. We do this by�rst highlighting some unique features of rockpools, especially focusing on their spatial orga-nization, physical structure and hydrological dis-turbance regime that impact ecological proces-ses both at the species and community level.Next, we present some examples of research thattackled questions in population genetics, com-munity ecology and evolutionary biology usingthese particular features. In the text boxes wepresent information on proven methods to studyparticular features of rock pool habitats and theirinhabitants. The current manuscript is comple-

Freshwater rock pools as model systems 27

Figure 1. Granite rock pool cluster on top of Walga Rock (Western Australia) (top picture); Isolated rock pool on Walloo Rock(Western Australia) (bottom left); Sandstone rock pool on Thaba Phatshwa (South Africa) (bottom right). Grupo de pozas en rocasde granito en la cima de Walga Rock (Australia Occidental) (fotograf�a superior); poza rocosa aislada sobre Walloo Rock (AustraliaOccidental) (inferior izquierda); pozas en rocas de arenisca sobre Thaba Phatshwa (Africa Meridional) (inferior derecha).

mentary to Jocque et al. (2010) that presentsan overview of world wide faunal diversity pat-terns in rock pools and a discussion of their con-servation. The same study also revises the che-mical and physical characteristics of rock poolsand presents their importance for phylogeogra-phical and biogeographical studies.

HYDROREGIME

Freshwater rock pools in most cases are tempo-rary habitats. Rock pools occurring in semi-arid

regions with low rainfall and high evaporation ra-te such as in southeast Botswana, for example,are described as highly unpredictable in both ti-ming and length of the inundation period (Bren-donck et al., 1998; 2000a). The length of the hy-droperiod averaged from several days up to littlemore than a month (Brendonck et al., 2000a).Rock pools in more temperate regions can be se-mi permanent, remaining inundated for severalseasons (Jocque et al., 2010).

The hydroregime (Hulsmans et al., 2008) is animportant but complex variable, which to a largeextent determines the composition, structure and

28 Brendonck et al.

diversity of rock pool communities as well as li-fe history strategies of populations. Hydroregimeencompasses a set of variables including the ave-rage length a pool remains inundated (hydrope-riod) and variance on this statistic, together withthe timing, frequency and periodicity of inunda-tions (Hulsmans et al., 2008; Vanschoenwinkel etal., 2009a). Time stress and particularly the mor-tality associated with desiccation can be conside-red as a severe form of disturbance (Therriault &Kolasa, 2001). Particularly desiccation frequencyand the prevalence of very short inundations (tooshort for reproduction) are directly related to thedisturbance regime of the rock pool habitat, as isvariably experienced by different local biota.

Studies on temporary water bodies often in-clude some hydrological monitoring (e.g. presen-ce/absence of water) (Fischer et al., 2000), butthe quantity and quality of most observations aretypically inadequate to quantitatively characte-rize long term hydrological dynamics (but seeBrooks, 2004; Bauder, 2005). Hydroregime can-not be reliably estimated on short term observa-tions, but often it is possible to use proxies fora good approximation. Morphometrical variablesare commonly used as proxies for hydroregime(Marcus & Weeks, 1997), but care should be ta-ken for collinearity of different contributing hy-drological variables as this may prevent unequi-vocal explanation of measured responses. In rockpools the use of morphometrical basin properties(e.g. depth) as proxies for aspects of pool hy-droregime, such as hydroperiod, can be justi�ed(Jocque et al., 2006). Basin depth and even poolarea commonly tend to be correlated variables re-lated to hydrological stability such as average andmaximum hydroperiod (Altermatt et al., 2009).Still, even weak collinearity between morphome-try and hydrology may prevent unequivocal ex-planation of measured responses in terms of ha-bitat size, habitat duration or patch disturbance(Vanschoenwinkel et al., 2009a).

A robust, quantitative description of hydro-regime requires the incorporation of daily, sea-sonal, and inter annual components of hydro-logical variation over an ecologically relevanttime frame. Long time series would permit inclu-sion of effects of cyclic climate phenomena (for

example, El Nino-Southern Oscillation, ENSO;North Atlantic Oscillation, NAO) and anthropo-genic climate change on hydroregime characte-ristics (Pfeifer et al., 2006). Although capabili-ties for in situ observation continue to improverapidly (e.g. using water depth data loggers or viaremote sensing),modellingprovides the onlygene-ral approach capable of reconstructing historic pat-terns of hydrologic variability and simulating sensi-tivity to future conditions (Pyke, 2004) (seeBox1).

Examples of applications of hydrological mo-dels to reconstruct rock pool hydroregimes arepresented in Hulsmans et al. (2008) and Vans-choenwinkel et al. (2009a). A similar bucket mo-del was developed by Altermatt et al. (2009).Hulsmans et al. (2008) used model simulationsto investigate long term patterns of seasonal andinterannual variation in hydroregime for rockpools in southeastern Botswana. Simulations in-dicated large variation in individual hydroperiods(76-115%) as well as in the number of hydro-periods per year (19-23%). Vanschoenwinkel etal. (2009a) reconstructed the hydroregime of 36rock pools on one outcrop in South Africa. Ave-rage predicted hydroperiod varied between threeand 101 days. Predicted inundation frequencyranged from three to 17 inundations per year. Va-riation in predicted hydroperiod was high, withstandard deviations ranging from three days forsmall shallow pools up to 171 days for large deeppools, resulting in a signi�cant correlation bet-ween standard deviation on the hydroperiod, ma-ximum depth, and pool area, respectively. Va-riation in number of inundations was relativelylow with standard deviations ranging from twoto four inundations per year. In addition, Huls-mans et al. (2008) simulated hydrological con-ditions associated with potential climate changescenarios and evaluated these with respect to thebiological requirements of the anostracan Bran-chipodopsis wol�, a peculiar inhabitant and keystone species in this habitat. It was suggested thatclimate change would signi�cantly alter the rockpool hydroregime with decreasing suitability forB. wol�. These �ndings con�rmed the hydrolo-gic sensitivity of ephemeral rock pool habitatsto precipitation patterns, and their potential sen-sitivity to future climate change.


Box 1.- Method to assess rock pool hydroregime

The first step in determining the hydroregime is to acquire a reliable estimate of the water balance of

a pool. This procedure is much simpler for rock pools than for other temporary aquatic habitats since they

occur as depressions in impermeable bedrock (usually granite or sandstone) and are often characterized by

steep edges. As a result they can be idealized as buckets. For rock pools, therefore, a combination of a limited

number of field calibrations and the availability of precipitation and evaporation data can be sufficient to

satisfactory predict the presence of water (Hulsmans et al., 2008) or water volume in individual pools

(Altermatt et al., 2009; Vanschoenwinkel et al., 2009a) from simple models. Based on the output of the

model, a time series of water levels can be obtained with a daily resolution.

Once the model has been calibrated and validated by comparing its output to actual water levels of

individual pools measured in the field, their hydroregime (disturbance regime) can be reconstructed using

long term climatological data. From the generated water level time series, a number of hydrological variables

can then be calculated such as: average hydroperiod and inundation or desiccation frequency as well as the

intra and inter annual variation of these variables.

Making use of existing climate change scenarios, the effects of climate change on rock pool

hydroregimes and closely related abiotic factors such as salinity can be simulated. In case the critical time

periods needed for growth and reproduction for different taxa is known, one could carefully hypothesize

potential effects of increased time stress or relaxation of current temporal constraints in the future on species

composition, biotic interactions and, possibly to some extent, ecosystem functioning. The dependence of rock

pools on precipitation directly links this habitat with the reigning climate in a region and could therefore be a

sensitive barometer for climate changes.

SPATIAL SETTING OF POOLS AND POOLCLUSTERS

An important feature of rock pool systems is awell de�ned spatial hierarchical structure whichis expressed at three different levels (Fig. 2). Po-pulations and communities are usually assumedto be limited to the pool boundaries, althoughmany actively dispersing pool inhabitants maytravel regularly among pools during their life-span. The �rst level of spatial organisation isthe typical spatially clumped occurrence of rockpools arranged in clusters of potentially interac-ting pools (Fig. 2a). One or sometimes several ofsuch pool clusters can often be found at the sum-mit of dome shaped rocky outcrops or inselbergs(secondary spatial structure, Fig. 2b). These in-selbergs, in turn, form isolated units embedded ina terrestrial landscape matrix of habitat which isusually unsuitable for rock pool species (tertiaryspatial structure, Fig. 2c).

Inselbergs occur globally in all major bio-mes and are often distributed over large areasin high densities crossing multiple environmen-tal gradients as is for instance the case in large

parts of Western Australia and the Ivory Coast.The number of pools and pool clusters presenton individual inselbergs is highly variable. Usua-lly only one pool cluster is present, although lar-ge mountains such as the Korannaberg in SouthAfrica and several outcrops in Western Australiahold many isolated clusters. The number of poolscan vary between one and more than 1,000, as isthe case for some inselbergs in Western Austra-lia. Pools typically show variable degrees of iso-lation and connectivity. Some methods to assesspool isolation and connectedness are suggestedin Box 2. In some cases pools occur widely scat-tered over large areas as is the case on the giantsandstone slabs in Moab, Utah.

LOCAL PHYSICAL STRUCTURE ANDABIOTIC ENVIRONMENT

Rock pools around the world have a very similargeomorphological structure and abiotic environ-ment. They all originate through weatheringand erosion (Campbell, 1997; Dominguez-Villar,2006), resulting in a similar geomorphology of

30 Brendonck et al.

Box 2.- Methods to assess spatial structure.

Two spatial variables that are informative and easy to assess are pool isolation and connectedness. Pool

isolation can be calculated as the average distance to another pool in the cluster (sum of all the nearest

edge to edge distances to all the other pools divided by the number of other pools). Connectedness, in

turn can be quantified as the sum of all overflows arriving (and departing) from the pool in question

(i.e. number of connecting elements).

Depending on the characteristics of connecting elements (length, diameter, water flow, wind direction),

weighing factors can be included to improve the connectivity matrix. Similarly the size of source

populations could potentially be accounted for in the light of density dependent dispersal. In more

complex clusters, GIS modeling may help to calculate ‘resistances’ of different connections (Michels et

al., 2001). The main advantage of using simple variables is that they are easy to interpret in terms of

ongoing dispersal dynamics. It must, however, be noted that the presented isolation measure is only

accurate when all pools present have been sampled. If only a limited number of pools are sampled,

estimates of the number of neighbors that lie within a certain radius may be more informative. In order

to get a complete picture of spatial patterns over different spatial scales more sensitive methods have

been developed such as Principal Coordinate Analysis (PCoA; Gower, 1966; Legendre & Legendre,

1998), Principal Coordinates of Neighbouring Matrices (PCNM; Borcard et al., 2004) and the

construction of third degree polynomials of X and Y coordinates (Cottenie et al., 2003). Results

obtained using these methods, however, tend to be less straightforward to interpret. Sensitive methods

to detect spatial variation such as the latter, when used to explain community patterns, for instance, are

also more likely to pick up ‘hidden’ environmental gradients which may result in overestimation of the

importance of space.

the basin, only varying in surface and depth.Rock pools are usually pan or bucket shaped witha cylindrical or ellipsoid surface and variable di-mensions. Weathering and erosion may lead tofusion of neighbouring pools resulting in morecomplex shapes (Twidale & Corbin, 1967).

This comparable and simple environment isa major advantage as it allows for joint analysisof patterns across different spatial scales betweenpool systems in different regions and even acrosscontinents. A detailed overview of the chemicaland physical conditions in rock pools is presen-ted in Brendonck et al. (2001) for Southern Afri-can rock pools and at a global scale by Jocqueet al (2010). In general, basins are �lled withrain water, resulting in a highly diluted environ-ment at the start of the inundation with conduc-tivities below 10 µS cm−1, approaching those ofdistilled water. The generally shallow rock pools,with water depth usually varying between 5 and30 cm, have poor buffering capacity to environ-mental changes, closely follow air temperature,and also show large diurnal �uctuations in pHand dissolved oxygen.

LOCAL BIOTIC ENVIRONMENT

As in other types of temporary aquatic systems,rock pool animals can be roughly divided in tho-se that permanently reside in the habitat, evenduring the dry phase (as resistant life stages),and those that migrate to more permanent sys-tems when pools are drying out (Wiggins et al.,1980). The highly variable environmental con-ditions combined with a relatively unpredicta-ble �ooding regime select for a specialized faunawith a high tolerance to stress and often speci-�c adaptations for surviving the dry phase. Mostpool species survive via resting propagules (e.g.dormant eggs), desiccation resistant larvae or byactive migration and recolonization (Wiggins etal., 1980; Brendonck & De Meester, 2003).

Rock pools are suitable systems to study tro-phic interactions and food web dynamics. Incontrast to the commonly quoted description oftemporary pools as ‘enemy-free’ habitats (Fryer,1986; Kerfoot & Lynch, 1987), predation, in fact,is important in rock pools and has been shownto be an important community structuring fac-


tor. Common predators in rock pools are the cla-wed toad (Xenopus laevis) (Hamer & Martens,1998) in Africa, Turbellaria (Mesostoma spp.)(Brendonck et al., 2002; De Roeck et al., 2005 ),different types of insect predators (e.g. notonec-tids, odonates, corixids, dytiscids (Brendonck etal., 2002) and ceratopogonid midge larvae (Vans-choenwinkel et al., unpub data). Certain preda-tory water mites are also common inhabitants ofrock pools worldwide which colonize pools afterthey have been inundated (Jocque et al., 2010).Predation pressure typically increases towardsthe end of inundations (Schneider & Frost, 1996;Spencer et al., 1999). Factors contributing to thispattern are delayed arrival of actively migratingpredators (Jocque et al., 2007), concentration ofpredators due to evaporation of the water and thetime lag that certain predators require to matureand become predatory. This is for instance the casewith tadpole shrimps (Triops sp.) and turbellarians.

Besides predation, also competitive interac-tions were shown to be important in rock pools,notably between the two dominant groups of �l-ter feeding rock pool crustaceans; fairy shrimp(Anostraca) and water �eas (Cladocera). Fairyshrimp are the dominant �lter feeders early du-ring inundation and outcompete smaller cladoce-rans in �eld enclosures (Jocque et al., in press b).The authors argued that a trade off between pre-dation sensitivity and competitive strength pro-vides a likely explanation why the large fastgrowing fairy shrimp are dominant early du-ring inundations and are later replaced by preda-tion resistant Cladocera. Long term observations(> 17 years) in a Daphnia metacommunity inha-biting coastal rock pools in Finland revealed howsubtle niche differences in combination with fre-quent extinction and colonization processes me-diate species coexistence in naturally fragmentedhabitats (Hanski, 1983; Pajunen & Pajunen, 2007).

For an extensive review of biotic interactionsin rock pools we refer to Jocque et al. (2010).

DISPERSAL DYNAMICS

The spatial structuring of rock pools (Fig. 2), pro-vides opportunities to directly study the spatial

interactions between communities and popula-tions and quantify the exchange of species andgenotypes, respectively. Different methods ha-ve been developed to intercept dispersing orga-nisms, notably at local within cluster scales andmainly for passive dispersers (Vanschoenwinkelet al., 2008a). Little is known about the dyna-mics of dispersing adult aquatic insects and am-phibians. Within pool clusters, passively disper-sing animals are dominantly dispersed by windand over�ows between pools and to a lesser ex-tent by animals.

During heavy rains, rock pools may over�ow.This water, which may hold animals and dormantlife stages, is generally lost in the surroundinglandscape matrix and is expected to result in se-rious losses, especially for populations situatedat the margin of the outcrop. Occasionally, watermay �ow from one pool to another, facilitatinghydrochorous dispersal. For rock pools in south-eastern Botswana, Hulsmans et al. (2007) quan-ti�ed the number of viable dormant eggs and lar-vae dispersed by over�ows, making use of traps(see Box 3). Up to 784 viable eggs and 301 lar-vae of the anostracan B. wol� were captured du-ring one single rainfall event. Trapping of dis-persing propagules in over�owing water duringa heavy downpour, revealed dispersal rates up to128 eggs and 46 larvae per hour. With a similarsetup, Vanschoenwinkel et al. (2008a) estimatedan average dispersal rate of 4,088 propagules perchannel per year for rock pools in a South Afri-can cluster.

Brendonck & Riddoch (1999) provided �rstexperimental evidence in support of wind as a lo-cal dispersal vector in the fairy shrimp B. wol-� by means of sticky traps (see Box 3) mountedaround and between rock pools in the dry season.Also using sticky traps, Vanschoenwinkel et al.(2008a) collected very high numbers of propagu-les (average propagule rain: 649 propagules/m2

in one month) in a pool cluster in South Afri-ca. Collected propagule densities, however, de-creased dramatically beyond several meters frompotential source populations. The importance ofwind as dispersal vector was also demonstratedwith the use of wind socks (see Box 3) (Vans-choenwinkel et al., 2008b). Using nine wind

32 Brendonck et al.

a.) Rock pools as aquatic archipelagos

b.) Multiple pool clusters on top of a rocky outcrop

c.) Rocky outcrops as islands in the regional landscape matrix

Figure 2. Different levels of spatial hierarchical organization, characteristic of freshwater rock pool habitats a.) pool clusters oftensituated near the summit of rocky outcrops; b.) rocky outcrops containing multiple pool clusters; c.) rocky outcrops (inselbergs) asinteracting units in the regional landscape. Distintos niveles de organizacion jerarquica espacial, caracter�stica de los habitats depozas en rocas: a.) grupos de pozas frecuentemente situadas cerca de la cima de elevaciones rocosas; b.) elevaciones rocosas quecontienen pozas en grupos; c.) elevaciones rocosas (inselbergs) como unidades interactivas en el paisaje regional.

socks, about 850 propagules (mostly dormanteggs) of 17 taxa were captured during one month.The key factors determining yields, were the pre-sence of water in the pools directly affecting thelevel of exposure of the dormant propagule bankand the dominant wind direction. Temporal va-riation in wind speed, surprisingly, was not im-portant in this study. As rock pools often occurrather exposed on the top of outcrops, wind is ex-pected to be not only of importance for local butpotentially also for long distance dispersal.

Fragmented observations support a limitedpotential for zoochory. Mainly amphibians suchas the African clawed frog (Xenopus laevis) andpotentially also aquatic insects (Van De Meut-ter et al., 2008) or songbirds, which only rarelyvisit rock pool sites, are potential vectors. Con-trary to other aquatic systems in which they ha-ve shown to be important vectors (Figuerola &Green, 2002), waterfowl is largely absent. Vans-choenwinkel et al. (2008a) isolated invertebra-te propagules from the faeces of African clawed


Box 3.- Methods to measure wind (anemochorous) and overflow (hydrochorous) dispersal.

Windsocks

Windsocks can be used to collect propagules that are lifted from the substrate. The windsock design used in

Vanschoenwinkel et al. (2008b) consists of a conical sock (100 µm mesh) with a diameter of 30 cm and a total length of 90 cm

attached to a stainless steel frame (Fig 3). The tip of the windsock is curved and a zipper is integrated 30 cm from the tip to facilitate

the removal of the collected samples. The metal frame consists of two stainless steel rings of 30 and 20 cm in diameter, respectively,

connected by four 30 cm long crossbars. This rigid structure ensures a fixed opening of the mouth of the wind sock, even under

conditions of low wind speed. The windsock is able to rotate freely around a stainless steel axis. Even with low wind speed the

mouth of the sock is always directed towards the current wind direction.The whole structure can be anchored in a plastic parasol

stand filled with sand.

Figure. 3. Detailed schematic drawing illustrating the design of the experimental wind socks. Essential parts such as the zipper to

detach the tip of the sock and the metal frame used to keep the mouth of the wind sock open at all times are indicated (figure taken

from Vanschoenwinkel , 2008b).et al. Diagrama esquemático que ilustra el diseño de las mangas de viento. Se han indicado las

partes esenciales como la cremallera para separar la punta de la manga y el armazón de metal utilizado para mantener la boca de

la manga de viento abierta en todo momento (figura tomada de Vanschoenwinkel , 2008b).et al.

Sticky traps

To measure wind dispersal at the level of the rocky substrate, sticky traps can be attached at variable distances from a pool.

Sticky traps exist of cardboard surfaces coated with about 2 mm layer of Tangletrap ® insect glue (Tanglefoot company) placed i n

the field. The glue is more or less water resistant but heavy rains will, nonetheless, destroy the set up.

Flow traps

To measure hydrochorous dispersal, the water in eroded channels between pools can be guided through a central plastic cup

lined with a fine (64-µm) mesh by means of clay dams (Fig 4). Influx of wind blown propagules in dry cups should be avoided by

thoroughly rinsing the cups prior to rainstorms. Cups can be removed and transported to the lab for study of collected propagules

immediately after overflow events.

Figure. 4. Schematic diagram illustrating the experimental setup used to measure hydrochorous dispersal through

channels (overflow trap). All components including the clay dam and the plastic cup lined with fine gauze are indicated

(figure taken from Vanschoenwinkel , 2008a).et al. Diagrama esquemático que ilustra el diseño experimental utilizado

para medir la hidrocoria a través de un canal (trampa de rebosadero). Se indican todos los componentes, incluyendo el

dique de arcilla con el vaso de plástico con un fondo de malla fina (figura tomada de Vanschoenwinkel , 2008a).et al.

channel

pool A

plastic cup

pool B

water flow

clay dam 64 m gauzeµ

90 cm

30 cm

axis

frame

zipper

detachable tip

34 Brendonck et al.

frogs (Xenopus laevis) and counted on average368 propagules per frog after 24 hours. Amphi-bian mediated dispersal was considered of limi-ted importance as the Xenopus laevis populationwas small and migrations rare.

To date it largely remains unknown to whatextent dispersal capacity varies among taxa andhow it is related to size and shape of disper-sing propagules. As an attempt to �ll this gap,Vanschoenwinkel et al. (2009b) compared dis-persal capacities and modes of freshwater inver-tebrates in a cluster of temporary rock pools inSouth Africa making use of a combination ofwindsocks (1.5 m above ground level) and stickytraps (ground level). Differences were detectedin the composition of dispersing communities in-tercepted at these different altitudes. Comparisonof dispersal distance distributions also revealedsigni�cant differences among taxa. Larger pro-pagule types (e.g. adult ostracods and oribatidmites) predominantly travelled near ground le-vel while small dormant eggs and cryptobiotic li-fe stages of copepods were most frequently in-tercepted at higher altitudes (up to 1.5 m) anddispersed over the longest distances. Almost allpropagules were able to reach the most isolatedtraps in the study (30 m from a nearest pool) sug-gesting that dispersal at such local scales is notlimiting. To simulate the potential movement ofpropagule bank fragments, differently sized arti-�cial substrate fragments similar to dry propa-gule bank fragments were arranged in the drypool basins and their inter pool movements we-re mapped. Both interception of dispersing na-tural propagule bank fragments and observedsuccessful inter pool dispersal of arti�cial subs-trate fragments, suggested that not only dispersalof single propagules but also ground level trans-port of propagule bank fragments can contributeto local dispersal dynamics.

META-STRUCTURES OF POPULATIONSAND COMMUNITIES

The spatial hierarchical structure of the habitatcombined with the unique opportunity to quan-tify patch disturbance regimes (Box 1), isolation

and connectedness (Box 2) and local dispersaldynamics (Box 3) make that rock pools can beconveniently used to test predictions of meta-population and metacommunity models. Besidesthe possibility to study spatial interactions bet-ween communities and populations at local sca-les, the ancient habitat (old rock formations) andglobal distribution of rock pools makes them at-tractive habitats for biogeographic and phylogeo-graphic studies (see Jocque et al., 2010).

Populations

In a series of studies with increasing numbersof populations and metapopulations in south-eastern Botswana, the genetic structure of therock pool anostracan B. wol� was studied bymeans of allozyme electrophoresis (Riddoch etal., 1994; Brendonck et al., 2000; Hulsmanset al., 2007). Rock pool sites differed in number,size and connectivity of pools. Genetic diversitywas signi�cantly lower in populations residing atthe outcrop with shallower pools and shorter hy-drocycles (Brendonck et al., 2000; Hulsmans etal., 2007). This could be linked to a greater in-cidence of extinction and recolonisation in thesebasins (genetic bottlenecks). Across all local po-pulations, a signi�cant level of population diffe-rentiation was usually revealed. More than 90%of this variation was explained by differentia-tion among pool clusters (metapopulations), al-though this differentiation did not correlate withgeographic distance, or with environmental dif-ferences (Brendonck et al., 2000; Hulsmans etal., 2007). Low levels of genetic differentiationwithin pool clusters suggest signi�cant levels ofshort distance dispersal and gene �ow. Rare longdistance dispersal events, possibly enhanced byfounder effects, on the other hand, were most li-kely responsible for higher levels of differentia-tion among pool clusters on different outcrops.

Genetic differentiation among populationswithin metapopulations was low, but signi�cantat all sites. Riddoch et al. (1994) at one siteand Hulsmans et al. (2007) at three sites, de-tected clear isolation by distance patterns. Gene�ow estimates indicated from 0.6 to 227 migrantsper generation. This corresponded with direct ob-


servations of high dispersal rates by means ofover�owing pools (Hulsmans et al., 2007). Ba-sed on these allozyme data, distances of about50 m appeared to be effective barriers for gene�ow (Hulsmans et al., 2007).

Communities

Using the output of a hydrological model (seeBox 1) combined with a detailed description ofthe morphometry of the study pools, Vanschoen-winkel et al. (2009a); demonstrated that both hy-droregime and habitat size had unique and sha-red effects on temporary pool biota and that theseeffects depended on the dispersal mode (passiveversus active) of the considered taxa. As expec-ted, hydroregime was more important for passivethan for active dispersers.

Of different metacommunity perspectives,a combination of species sorting and masseffects best explained distribution patterns in acluster of 36 temporary rock pools in centralSouth Africa (Vanschoenwinkel et al., 2007).The relative importance depended largely ondispersal strategy (active versus passive). Spatialvariables were only important for passive dis-persers and signi�cantly explained 11% ofvariation in this community component. Poolsconnected by temporary over�ows hosted moresimilar communities of passive dispersers thanunconnected ones, while community dissimi-larity signi�cantly increased with inter pooldistance. In addition, a negative curvilinear rela-tion was discovered between taxon richness andisolation in passive dispersers. A similar diffe-rential response to spatial versus environmentalvariables was found between generalist andspecialist species in a long term data set oninvertebrate communities in coastal rock pools inJamaica (Pandit et al., 2009). These authors con-trasted metacommunity structure of generalistsand specialists and concluded that the distribu-tion of generalists responded more to regional(spatial) processes while specialists dominantlyresponded to local processes (species sorting).Beside mass effects and species sorting, low dis-persal rates (dispersal limitation) likely affected

the communities in this system. Dif�culties indistinguishing the nature of spatial effects in rockpool metacommunities, which can arise due tohigh (mass effects) or low dispersal rates (dis-persal limitation), were discussed by Ng et al.(2009). By comparing the importance of spatialand environmental effects at different spatial sca-les the authors were able to conclude that the spa-tial effects in their dataset most likely resultedfrom dispersal limitation operating among poolclusters separated by a distance of 2 km.

Succession and community assembly

Jocque et al. (2007) studied invertebrate com-munity assembly and dynamics in 16 ephemeralrock pools (lasting from less than a week to aboutone month) at two rock pool sites in Botswana.The goal of this study was to verify whether suc-cession or replacement of species could be de-tected in short lived pools where early desicca-tion is likely to truncate community assembly.Data were collected every two days during a fullinundation cycle. All communities were initiallyassembled by permanent residents (passive dis-persers) recolonising the habitat from dormantegg banks to which actively dispersing ephe-meral taxa were added later in the hydrocycle.Species replacements only occurred in a smallfraction of pools, especially in those with thelongest hydroperiods. Concurrent with a decreasein the densities of the anostracan B. wol�, popu-lation sizes of Leberis sp. and Culicidae (Aedessp. and Anopheles sp.) increased in these pools.Although it was possible to distinguish two suc-cessional phases at one rock pool site, commu-nity assembly was generally a gradual processdetermined by dispersal strategies of the inha-bitants. Additional rains after initial �lling trig-gered dispersal by active dispersers and positi-vely in�uenced colonization success. A reducedhydroperiod shortened the community develop-ment down to a critical point below which lackof time eliminated the possibility of species re-placements. Based on these �ndings, ephemeralwaters were de�ned as aquatic habitats lackingspecies replacements.

36 Brendonck et al.

RISK SPREADING STRATEGIES ANDADAPTATIONS TO VARIABLEDISTURBANCE REGIMES

A major stress factor for permanent inhabitantsof temporary rock pools, especially in arid re-gions, is the possibility of elimination of the po-pulation by premature drying. Persistence in thisenvironment under time stress therefore not onlyrequires adaptations in life history characteristicsof the active population but also in hatching be-havior of the resting stages.

Particularly the life history characteristics offairy shrimp (Anostraca) in relation to the hydro-regime are well studied in rock pools. Branchi-podopsis species in general are real champions inracing against time to mature before the habitatdisappears. Laboratory and �eld observations byHamer & Appleton (1996) revealed rapid growthand early maturation (4-6 days after hatching) ofB. tridens, B. wol�, B. dayae and B. browni (allinhabiting rock pools). Species inhabiting rockpools in the southern African Drakensberg alsoreached sexual maturity in a matter of days (Ha-mer & Martens, 1998). Female populations of B.wol� started to produce dormant eggs after �vedays and were fully mature within eight days inmost pools (Brendonck et al., 2001). Maturationrate was faster in the shorter lived and/or moreunpredictable pools (Brendonck et al., 2001). Li-fe span of rock pool Anostraca lasted less thanfour (Hamer & Appleton, 1996) or six weeks(Hamer &Martens, 1998). Broods tended to havesmaller eggs in more unpredictable pools (Bren-donck et al., 2001). Brood sizes varied between40 and 80 eggs in specimens from the Drakensbergregion in South African (Hamer &Martens, 1998).

Models developed for desert annual plantspredict that high variation in reproductive successamong growing seasons (Cohen, 1966, 1967,1968) may promote selection for prolonged dor-mancy with hatching percentages correspondingwith the chance of successful recruitment. Suchdelayed germination of a variable portion of the‘seed bank’ can be considered an evolutionaryrisk spreading strategy (bet hedging) which en-tails that the geometric mean �tness over timecan be maximized by reducing the variance in �t-

ness, at the cost of the arithmetic mean �tness ofeach generation (Philippi & Seger, 1989). Littleempirical work has been done so far to deter-mine the relationship between the average chan-ce of successful recruitment and germination orhatching fractions (Philippi, 1993a,b). Scatteredexperimental evidence suggests that certain rockpool inhabitants may have adopted such strate-gies. The delayed hatching of part of the eggbank of B. wol�, for example, served as a hed-ge against at least 16 subsequent drought catas-trophes (Brendonck et al., 1998). Hatching per-centages under realistic �eld temperatures after�lling of pools (20-30 ◦C), ranged between about3 and 20%, which corresponded well with es-timates of the probability of successful re-cruitment based on long term climatic records(Brendonck & Riddoch, 2001). Van Dooren &Brendonck (1998), showed that variability in hat-ching response even occurs in single broods andcould therefore be considered a diversi�ed bet-hedging strategy. Egg banks furthermore revea-led conditional responsiveness to ecologicallyinformative hatching cues (temperature, conduc-tivity), restricting hatching to initial or additio-nal rains, resulting in an association between hat-ching and the likelihood of completing a lifecycle (Brendonck et al., 1998). The relativelyhigh egg densities of egg banks of between about1,000 and 220,000 eggs per m2, depending onseason or year, illustrate the effectiveness of thereproductive and hatching characteristics of thisspecies (Brendonck & Riddoch, 2000).

ROCK POOLS AS A MODEL SYSTEM,WHERE AREWE NOW?

According to Levins (1984) and Srivastava etal. (2004) a good ecological model system ischaracterized by the following features: tractabi-lity, generality and realism. Rock pool systemsinarguably exhibit a number of characteristicswhich make them ‘easy to use’. However, be-sides the practical advantages of working withsmall, pristine and structurally simple systemsand the possibility to quantify processes whichare hard or impossible to quantify in larger mo-


re complex systems, rock pools also have theadvantage that their basic properties and spatialcon�guration closely resemble theoretical meta-population and metacommunity models (Bengts-son, 1989). Perhaps the most important propertythat makes small aquatic systems attractive to testmodel predictions is the presence of clear boun-daries which are often highly ‘fuzzy’ in othersystems. Short lifespan of the organisms presentin rock pools and small aquatic habitats in ge-neral also allow observing population and com-munity dynamics within a relatively short time-frame while comparable observations on largerorganisms would require vast amounts of time.Due to the simple morphometry of rock pool ba-sins and the lack of any groundwater interactions,rock pool hydrologies are simple allowing to re-liably reconstruct the disturbance regime againstwhich patterns of variation in life histories, po-pulation genetics, species richness and communi-ty structure can be interpreted.

However, despite these advantages, the spe-ci�c knowledge on this habitat is limited. Rockpool systems in regions such as South Americaand Asia remain unstudied and the number of re-search groups systematically using rock pools asstudy habitat is also small.

A �nal consideration is here at place. Rockpool systems are peculiar systems which in cer-tain aspects can be considered ecological odd-balls (Srivastava et al., 2004) and some care isneeded before generalizing processes and pat-terns observed in this habitat. Compared to otherhabitat types, rock pools, for instance, exhibit asevere form of disturbance in terms of a recu-rring dry phase. Consequently animals that occurin these habitats can all, to some extent, be con-sidered disturbance specialists. Rock pools alsogenerally house very small populations compa-red to larger habitats such as ponds and lakesand as a result may be more sensitive to externalin�uences. Evidence also suggests that local ex-tinctions occur relatively frequently. Contrary tomost other ecosystems, genetic bottlenecks, lowgenetic diversity and most likely also priority ef-fects may be common in rock pool habitats andare likely to affect the evolutionary trajectoriesof populations (Haag et al., 2005).

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Temporay ponds from Donana National Park: a system of naturalhabitats for the preservation of aquatic �ora and fauna

Carmen D�az-Paniagua 1,∗, Roc�o Fernandez-Zamudio2, Margarita Florencio1, Pablo Garc�a-Murillo2, Carola Gomez-Rodr�guez1, Alexandre Portheault1, Laura Serrano2 and Patricia Sil-jestrom3

1 Estacion Biologica de Donana-CSIC, Apartado 1056, 41080 Sevilla, Spain.2 Dept. Plant Biology and Ecology, Univ. Sevilla.3 Instituto de Recursos Naturales y Agrobiolog�a Sevilla-CSIC.2



ABSTRACT

Temporay ponds from Donana National Park: a system of natural habitats for the preservation of aquatic �ora andfauna

Mediterranean temporary ponds are a priority habitat under the European Union Habitats Directive, but those of natural originare scarce, as many of them have been destroyed or transformed into permanent waters. The aim of this study is to highlightthe conservation value of the system of temporary ponds in Donana National Park, where more than 3000 water bodies maybe �lled during wet years. They are located on soils of aeolian origin where water persistence is favoured by the presenceof an argilic semi permeable horizon and by a relic clay-rich sandy layer. Temporary ponds can be classi�ed across a widehydroperiod gradient. Most ponds �ll with autumnal or winter rains and persist up to late spring or summer, and only a fewmaypersist through summer. Eight of the 11 amphibian species of this area require temporary ponds for breeding. More than 124taxa of macroinvertebrates have been recorded, coleopterans (56 taxa) and heteropterans (19 taxa) being the richest taxonomicgroups. Several zooplankton species are endemic to this kind of habitats, such as the copepod Dussartius baeticus and therotifer Lecane donyanensis. Regarding vegetation, at least 55 hydrophytes species were identi�ed in the ponds sampled, andalso some species endemic to SW Iberian Peninsula (Callitriche regis-jubae, Scorzonera �stulosa, Callitriche lusitanica) andothers are in relic situation (Hydrocharis morsus-ranae, Thorella verticillato-inundata, Lemna trisulca). The conservationvalue of these ponds is highlighted by the large variety of protected and/or rare species of �ora and fauna, which are favouredby a high pond abundance and connectivity.

Key words: Temporary ponds, conservation, aquatic fauna, aquatic vegetation, macroinvertebrates, amphibians.

RESUMEN

Las lagunas temporales del Parque Nacional de Donana: un sistema de habitats naturales para la conservacion de la �oray fauna acuaticas

Las lagunas temporales mediterraneas son habitats prioritarios incluidos en la Directiva de Habitats de la Union Europea,que han sido frecuentemente destru�dos o transformados en medios permanentes, siendo actualmente escasos los de origennatural. Este estudio pretende resaltar la importancia que tiene el sistema de charcas temporales del Parque Nacional deDonana en la conservacion de �ora y fauna acuaticas. Este sistema comprende mas de 3000 cuerpos de agua en anoslluviosos, localizandose en las zonas de origen eolico, donde la permanencia del agua se ve favorecida por la presencia ensus suelos de un horizonte arg�lico y semipermeable y por una capa arenosa relicta rica en arcillas. Las lagunas temporalesse pueden clasi�car en funcion de su amplio gradiente de hidroperiodo. La mayor�a de ellas se llenan con las lluvias de otonoo invierno y pueden permanecer hasta el �nal de la primavera o principios del verano y solo algunas pueden mantener aguaen verano. Las lagunas temporales son los habitats de reproduccion de ocho de las 11 especies de an�bios que se encuentranen Donana. Se registraron mas de 124 taxa de macroinvertebrados, entre los que los coleopteros (56 taxa) y heteropteros(19 taxa) fueron los grupos taxonomicos con mayor numero de especies. En el zooplancton, destacan especies endemicas de

42 D�az-Paniagua et al.

este area, como el copepodo Dussartius baeticus y el rot�fero Lecane donyanensis. Entre las especies vegetales caracter�sticasde las lagunas temporales se han identi�cado mas de 55 hidro�tos, encontrandose ademas algunos endemismos del suroesteiberico (Callitriche regis-jubae, Scorzonera �stulosa, Callitriche lusitanica) , as� como especies amenazadas (Hydrocharismorsus-ranae, Thorella verticillato-inundata, Lemna trisulca). Las lagunas temporales de Donana son de gran importanciapara la conservacion de un amplio numero de especies protegidas y singulares de su �ora y fauna acuatica, que se venfavorecidas por la gran abundancia y conectividad de medios acuaticos.

Palabras clave: Lagunas temporales, conservacion, fauna acuatica, vegetacion acuatica, macroinvertebrados, an�bios.

INTRODUCTION

Temporary ponds are aquatic environments withrecurrent periods of desiccation. Therefore, theiraquatic �ora and fauna is forced to endure thedry period through different mechanisms, such ascomplex life cycles including terrestrial phases,phases of resistance or dispersal to other habitats(Bronmark & Hansson, 2005; Williams, 2006).Strict aquatic species may not survive in theseponds. Another important characteristic of thesehabitats is the absence of predators common topermanent waters, mainly �shes, which in�u-ences the structure of their animal communities(Wellborn et al., 1996). In consequence, tempo-rary ponds support a different community struc-ture than permanent waters do (Collinson et al.,1995; Schneider & Frost, 1996; Della Bella et al.,2005; Cereghino et al., 2008) and hence deservespeci�c conservation and management programs.

For many years, conservation of aquaticecosystems has been mainly directed to perma-nent waters. Temporary ponds have often beeninconspicuous and poorly known due to theirtemporary nature and small size, and have beenfrequently destroyed by human action (Williamset al., 2001; Grillas et al., 2004; Williams, 2006;Zacharias et al., 2007). In particular, conserva-tion of temporary ponds is essential for speciesthat may not survive in more permanent aquatichabitats, such as some species of macrophytes(Nicolet et al., 2004; Della Bella et al., 2008),macroinvertebrates (Collinson et al., 1995; Nico-let et al., 2004; Cayrou & Cereghino, 2005; Bil-ton et al., 2008), and amphibians (D�az-Paniagua,1990; Grif�ths, 1997; Semlitsch, 2003).

Mediterranean temporary ponds are a priorityhabitat under the European Union Habitats Di-rective (Code 3170: European Commission DGEnvironment, 2007). They present a wide vari-ability in �lling onset and duration, dependingon rainfall input and pattern (Zacharias et al.,2007). However they may be distinguished fromother types of temporary ponds because they aremostly �ooded in autumn or spring and dry outfor several months in summer (Grillas et al.,2004). Mediterranean temporary ponds of natu-ral origin are scarce, as their importance is oftennot appreciated and many of them have been de-stroyed or transformed in permanent water (Gril-las et al., 2004). In this category there are alsoincluded many ponds derived from human ac-tivities, for example those used in agriculturefor livestock watering (Beja & Alcazar, 2003;Denoel, 2004; Stamati et al., 2008) or gravel andmining pits of historic origin (Jakob et al., 2003).

The Donana National Park is one of themost important wetland areas in Western Eu-rope, being UNESCO Biosphere Reserve andRamsar site (see e.g. Garc�a Novo & Mar�n,2006). However, despite comprising a large num-ber of small Mediterranean temporary ponds (seeGomez-Rodr�guez et al. 2008; Gomez-Rodr�guez,2009), these have been frequently disregarded inmost faunistic and ecological studies which havetraditionally focusedon themarshes (Garc�aNovo& Mar�n, 2006) and large ponds (Lopez et al.,1991; Serrano&Toja, 1995; Serrano et al., 2006).

The aim of this study is to highlight the con-servation value of this system of Mediterraneantemporary ponds for the preservation of aquatic�ora and fauna. As a mainly descriptive paper, we

Donana Temporary Ponds 43

have reviewed the previous information on fau-nistic and plant studies of these habitats and wehave also recorded new data to assess pond bio-diversity in different time periods. Our purposewas: 1) to bring out the existence of this tem-porary ponds system as an example of Mediter-ranean temporary ponds of singular importancefor their natural origin and for their present con-servation value, 2) to describe the high speciesrichness of different taxonomical groups in thesehabitats and 3) to describe the wide variation thatthe composition of these communities may expe-rience among different ponds and years.

MATERIALS AND METHODS

Description of the study area

The Donana National Park is located on theright bank of the Guadalquivir River mouth, insouthwestern Spain. From a geomorphogicalviewpoint, it comprises three different land-scapes: a marsh area, a mobile dune system run-ning parallel to the coast and a stable, older dunesystem, which occupies almost a third of the totalPark surface (Siljestrom & Clemente, 1990). Inthe stable dunes region, the geomorphology and

Figure 1. Main different ecological units within Donana National Park, with the number of ponds estimated in each zone in 2004(pond cartography extracted from Gomez-Rodr�guez, 2009). A: Northern stable dunes; B: Contact area between stable dunes andmarshes; C: Higher stable dunes; D: Contact area between stable and mobile dunes (peridune area); E: Mobile dunes; F: Southernstable dunes. The 18-21 ponds intensively sampled were located in the area included in the ellipse. Ninety ponds sampled once in2006 or 2007 were located through all the sandy area of the Park. Principales unidades ecologicas que se distinguen en el ParqueNacional de Donana, indicandose el numero de lagunas estimadas en cada zona en el ano 2004 (cartograf�a de lagunas extra�da deGomez-Rodr�guez, 2009). A: Arenas estabilizadas del Norte; B: Area de contacto entre arenas estabilizadas y marismas; C: Arenasestabilizadas de mayor altitud; D: Area de contacto entre arenas estabilizadas y dunas moviles (area peridunar); E: Dunas moviles;F: Arenas estabilizadas del Sur. Las 18-21 lagunas muestreadas con mayor intensidad se localizan dentro del area enmarcada porla elipse. Las 90 lagunas que se muestrearon una sola vez en 2006 o 2007 se encuentran distribuidas por las zonas arenosas de todoel Parque.


water table depth are the main factors affectingthe landscape and soil classi�cation, which willin�uence the density and extent of their aquaticenvironments. The northern part of the stabledune area (Fig. 1 A) is much older and erodedthan the southern part (Fig. 1 F), constituting theEroded Sand Sheet, and is where the main part ofthe temporary pond system is located. The water-table is close to the surface and the ground gets�ooded during wet periods, creating a great num-ber of temporary ponds. The southernmost part(Fig. 1 F), of recent formation and different soilcomposition, contains ridges and small depres-sions in which ponds are also created during therainy period. The Mobile Dune System (Fig. 1 E)is very dry, with the exception of some of the in-terdune valleys, due to the proximity of the water-table (Siljestrom & Clemente, 1990).

In contact areas between these landscapes,many ponds are formed (Gomez-Rodr�guez,2009) as result of discharges from the water-table. In the limit of the mobile dunes with thestable dune system (Fig. 1 D), the two nearly-permanent ponds of the Park may be found, aswell as a number of temporary ponds of wideextension and shallow depth �lled with drainagefrom the aquifer of the mobile dune system and ofthe eroded sand sheet. On the other hand, in theborder between the marsh and the stable dunes

(Fig. 1 B), ponds of different characteristics canalso be found (Siljestrom et al., 1994).

The climate of the area is Mediterraneanwith Atlantic in�uence, with warm and dry sum-mers and mild winters. Average annual rainfallis 544.6 (± 211.3) mm (as recorded from 1978-2008), with heavy rains mainly falling in autumnor in winter (Fig. 2) thus �ooding the temporaryponds after their summer desiccation.

Sampling and �eld work methods

In this study we have included data of annualrainfall recorded in a meteorological station lo-cated within the study area from 1978 to 2008.Annual rainfall data corresponded to the sum ofmonthly rainfall from September to the next Au-gust. Within this time period we were recordingdata for different studies in temporary ponds intwo periods: Between 1978 and 1985, and be-tween 1999 and 2008. In the �rst period we mon-itored amphibian species in 12 temporary ponds,for which we recorded data on �lling and desic-cation and the monthly variation of their maxi-mum depth. In the second period we intensivelymonitored 18 ponds for studies on amphibians,and 21 ponds (the previous 18 + 3 additionalponds) for macroinvertebrates and plant com-munities, and recorded soil samples. Six of the

Figure 2. Annual rainfall in Donana from 1978-2008. Each annual period includes data from September-August, classi�ed inseasonal periods. Precipitacion anual registrada en Donana entre 1978 y 2008. Cada periodo anual incluye datos de Septiembre aAgosto, clasi�cados en periodos estacionales.


ponds sampled in the �rst period were also sam-pled in the second period, providing a long timeseries of data on their hydroperiod and amphib-ian data. Pond hydroperiod was estimated as thenumber of months a pond was �ooded.

The number of ponds of the area was esti-mated with remote sensing analyses on a hy-perspectral image taken at a moment of largeinundation (see Gomez-Rodr�guez et al., 2008;Gomez-Rodr�guez, 2009 for details).

The soil of 21 ponds was prospected, sampledand described (using FAO, 1977; IUSS Work-ing Group WRB, 2006; and Soil Survey Staff,1993; 2006) by taking more than 60 boreholes intheir basins in 2007. Abundance of amphibianswere monthly sampled in 18 temporary pondsduring the inundation period from October 2002to July 2007, and macroinvertebrates and plantswere monitored in the same 18 ponds and threeadditional ones in 2006-2007. Amphibian larvaeand macroinvertebrates were sampled with a dip-net of 1 mm of mesh size, with which we cov-ered a length of approximately 1.5 m and wasrepeated, at least in 12 zones of the pond for am-phibians and 6 for macroinvertebrates, wheneverpossible. The amphibian larvae and macroin-vertebrates captured were identi�ed in situ andcounted and then released back to the ponds.Only some individuals of those species not iden-ti�ed in situ were preserved in 70 % ethanol forfurther identi�cation. All other individuals cap-tured were released in the pond. Macroinver-tebrates were identi�ed using the highest taxo-nomical resolution possible (usually species orgenus), except for Dipterans in which only Fami-lies were identi�ed. We have used the term “taxa”to count all different species, genera or fami-lies detected in the ponds. The same ponds weresurveyed to record the presence of hydrophytesspecies around and within the ponds, especiallyon the same points where macroinvertebratessamples were recorded. All plants were identi-�ed to species level in laboratory using referencebibliography (Valdes et al., 1987; Cirujano et al.,2007). The hydroperiod of these ponds were clas-si�ed in relation to the duration of the �oodedperiod in 2006-07: a) small ponds of shortduration (3-5 months); b) intermediate tempo-

rary ponds (5-6 months); c) extensive temporaryponds of long duration (> 6 months); d) pondsarti�cially deepened to hold water during sum-mer (locally named zacallones).

Additionally, 90 ponds were also sampled atleast once in 2006 and 2007, recording pres-ence data on macroinvertebrates, amphibians andplants. The physico-chemical characterization ofthese ponds water was based on data obtainedin spring 2007 (April-May). We measured max-imum depth, electrical conductivity (compen-sated at 25 ◦C), and pH in situ, and collectedwater samples for later determination of al-kalinity and concentrations of dissolved inor-ganic phosphate (i-P), NH+4 , SO

+4 , Cl

−, Ca2+, K+,Mg2+, and Na+ in the laboratory.

For those taxonomic groups which had beenintensively studied in this area, we also provideinformation from previous studies describing thenumber of species, and the main characteristicsof the groups related to their ecology in tempo-rary ponds, as in the case of planktonic micro-crustaceans and rotifers.

Although we performed intensive surveys onmacroinvertebrates and amphibians for the mostrecent period, in this study we only use these datato describe the importance of faunistic variationamong ponds and years, while other ecologicalaspects of the macroinvertebrates and amphibianassemblages of these ponds are being the object ofmore specific studies (see e.g. Gomez-Rodriguez,2009; Florencio et al., 2009). Therefore, in thisstudy we have tried to simplify our data by ex-tracting the information most representative ofdifferent types of ponds, selecting the results ofsix out of 18 ponds to represent the variation inpond depth, and of only three ponds for the varia-tion in interannual amphibian larvae abundances.

RESULTS

Geomorphology and Soils: Characterizationof Pond Types

Different soil structure was appreciated in pondsin relation to the different zones in which theywere located. In Northern stable dunes, ponds


had longer evolution time, and soils showed a su-per�cial, well developed, horizon of silty texturedue to the high organic matter content (satisfyingthe conditions of an Umbric or Mollic epipedon,Typic Humaquepts or Typic Haplaquolls) de-pending on the saturation. Other soils presentedMio-Pliocene semipermeable sediments nearer tothe pond ground surface, favouring the water ac-cumulation. In fact, these water dynamics maycause a �ne sediment layer accumulation whichcan act, through a positive feedback process, asa hanging water table. As a result, an argilic-type horizon in the pro�le may be identi�ed (ap-pearing between 30 and 60 cm and with variablethickness), which leads to a Typic Ochraqualfclassi�cation. At the border of the mobile dunesystem, in its contact with the stable dunes, thereare ponds which are nearly permanent with a hy-pogenic origin, fed from a deep water-table. Theyshowed no discontinuities in the pro�le and werecharacterized by a strong hydromorphic process-es in their pro�le, where an aquic soil moistureregime can be de�ned (classi�ed as Aquic Xerop-samments to Humaqueptic Psammaquents). Themost evolved soils presented a well developed or-ganic horizon which can be de�ned as Umbricepipedon (Typic Humaquepts). In the southernstable dunes, ponds showed the same character-istics as those located on the rest of sandy soilswith the exception of shell layers that conferredthem a certain amount (up to a 20 % in the �rst25 cm) of CO3Ca2 (Aeric to Typic Calciaquolls).Finally, ponds located in the contact area betweenthe stable dunes and the marsh are characterizedby a soil pro�le where multiple clayey interdig-itations may be found (Thapto Psammentic Pel-loxererts, among others) (Siljestrom, 1985).

Number of ponds

At the time of a large inundation event (April2004), more than 3000 water bodies were iden-ti�ed (see Gomez-Rodr�guez, 2009 for details onthis cartography). Ponds were not uniformly dis-tributed in the area, being the northern stablesands the area with the highest number of ponds(Fig. 1, A). The driest areas of the Park corre-sponded to the mobile dunes (Fig. 1, E) and the

high stable sands (Fig. 1, C), with ponds occur-ring only at lower altitudes on the stable sands. Inthe southern stable sands (Fig. 1, F), most pondswere man-made permanent water bodies consist-ing in deep and small (<10 m2) pits made for cat-tle drinking during summer (zacallones).

Interannual variation in rainfall and pondhydroperiod

Over the study period, we observed a wide vari-ability in annual rainfall and seasonality (Fig. 2).From 1978-2007, we detected 5 very wet yearswith annual rainfall > 712.8 mm and autumnheavy rains, and 5 very dry years with annualrainfall below 353.4 mm.

Ponds generally �lled after the �rst heavyrains. We have recorded the date of pond �ll-ing in 14 years: it occurred in autumn for 8years, and in winter for 6 years. Additionally, intwo very dry years, temporary ponds were not�ooded (1998-99 and 2004-05). Ponds �lled themonth in which rainfall accumulated an aver-age of 255.1 mm (sd = 54.2) since August. Wedetected a signi�cant correlation between themonth of pond �lling and the month when cu-mulative rainfall reached or surpassed 200 mm(rSpearman = 0.952, p = 0.00001).

In order to illustrate the wide variation indepth and hydroperiod that a same pond may ex-perience among contrasting hydrological yearswe selected six of the 21 ponds sampled in twoyears of different rainfall: 2005-06 an annual pe-riod of scarce rainfall and 2006-07, a rainy period(Fig. 3). As these six ponds included the largestvariation in hydroperiod, we did not include otherstudied ponds of similar variation. Ponds were�ooded in November in the wet year, when thoseponds with a shorter hydroperiod dried in May,persisting 6 months. Others persisted until Juneor July, with a hydroperiod of 8-9 months. Addi-tionally, in this wet year, other ephemeral pondswere �ooded later and persisted about 3 months.In the drier year, ponds neither �lled in au-tumn nor in winter, but in late January, and thepond with the longest hydroperiod persisted for5 months until July. The most ephemeral pondsof the wet year did not �ll during the dry one,


Figure 3. Cumulative rainfall and depth of six temporary ponds in two different years: 2005-06 (annual rainfall= 468 mm) and2006-07 (annual rainfall = 655 mm). A, B, C, D, E and F were the same ponds in both years (F was not �lled in the �rst year).Precipitacion acumulada y profundidad de seis lagunas temporales en dos anos de caracter�sticas diferentes: 2005-06 (precipitacionanual = 468 mm) y 2006-07 (precipitacion anual = 655 mm). A, B, C, D, E y F corresponden a las mismas lagunas en ambos periodos(F no se inundo durante el primer ano).

and short-hydroperiod ponds persisted only 1-3months. Ponds reached a higher extension anddepth during the rainy year.

Physico-chemistry of the ponds

Water physico-chemistry of ponds ranged widelyacross the National Park during spring 2007(Table 1). In general, most ponds were shallow(< 1m) freshwater environments with a circum-neutral pH and low ionic concentrations dominated

Table 1. Minimum, maximum and median values of mainphysico-chemical variables of temporary ponds in the study pe-riod (n = number of ponds sampled). Valores m�nimo, maximoy medianas de las principales variables �sico-qu�micas de laslagunas temporales en el periodo de estudio (n = numero delagunas muestreadas).

Variable min max median n

water depth (cm) 9 124 70 90

E.C. (mS cm−1) 0.09 9.87 0.50 90pH 5.4 10.4 6.8 87

Alkalinity (meq L−1) 0.10 15.97 2.52 39

Cl− (meq L−1) 0.55 30.99 2.37 39

Na+ (meq L−1) 0.02 27.56 2.98 39

Ca2+ (meq L−1) 0.05 7.25 1.15 39

Mg2+ (meq L−1) 0.18 11.99 0.98 39

SO2−4 (meq L−1) 0.04 2.89 0.36 39

K+ (meq L−1) 0.02 1.74 0.14 39

NH+4 (mg L−1) 0.04 3.59 0.04 90

i-P (µg L−1) 10 750 10 90

by NaCl. The concentration of dissolved inorganicphosphate was generally very low in spring 2007.

The vegetation of the ponds

A total number of 55 plant species were foundin the 21 temporary ponds sampled monthly(Table 2). We differentiated three main groupsof hydrophytes: hygrophytes, submerged macro-phytes and �oating macrophytes. The �rst groupincluded non strict aquatic plants, in which asubset of typical wet meadows species (�ood-plain species) were usually the main vegetationin ponds of short hydroperiod. Among these,graminean species such as Agrostis stolonifera,Paspalum paspalodes and Cynodon dactylonwere the most abundant, being frequently ac-companied by other weeds as Mentha pulegium,Baldellia ranunculoides, Myosotis ramosisssimaor Illecebrum verticillatum.

Another subgroup of helophytes is wetlandspecies, which inhabit the borders of ponds. InDonana it included Juncus maritimus, Eleocharispalustris and Eleocharis multicaulis amongothers. In deeper zones of the ponds, somespecies of submerged and �oating macrophyteswere frequent. The most common species wereJuncus heterophyllus and Ranunculus peltatus, aswell as Scirpus �uitans and different species ofCharophytes. In the deepest zones, the main veg-etation is represented by submerged plants, such


Table 2. Plant species recorded in 21 temporary ponds intensively surveyed and other species with special conservation valuerecorded in additional ponds through the Donana National Park. 1: semipermanent or zacallones; 2: long duration ponds; 3: intermedi-ate duration ponds; 4: short duration ponds; *: exotic invasive species. Especies de plantas registradas en las 21 lagunas temporalesque fueron muestreadas intensivamente, y especies con especial valor de conservacion registradas en otras lagunas temporales delParque Nacional de Donana. 1: semipermanentes o zacallones; 2: lagunas temporales de larga duracion; 3: lagunas de duracionintermedia; 4: lagunas de corta duracion; *: especies exoticas invasoras.

Helophytes Macrophytes

Floodplain species Wetland species Anchored (submerged or �oating leaves) Free-�oating

Agrostis stolonifera 1234 Cyperus longus 1234 Apium inundatum 234 Azolla �liculoides2∗

Anagallis arvensis 1 Eleocharis multicaulis 1234 Callitriche brutia 1234 Lemna minor12

Anagallis tenella 12 Eleocharis palustris 1234 Callitriche obtusangula 1234

Baldellia ranunculoides 1234 Galium palustre 124 Callitriche truncata subsp occidentalis1

Cotula coronopifolia 1234 Juncus maritimus 1234 Chara aspera12

Cynodon dactylon 1234 Juncus pygmaeus 2 Chara connivens12

Elatine alsinastrum 2 Scirpus cernuus12 Juncus heterophyllus 1234

Elatine hexandra 1 Scirpus holoschoenus 1234 Myriophyllum alterni�orum123

Eryngium corniculatum 12 Scirpus litoralis 12 Nitella �exilis12

Frankenia laevis 1234 Scirpus maritimus12 Nitella tenuisissima2

Glyceria spicata 1234 Scirpus pseudosetaceus 14 Nitella translucens34

Hydrocotile vulgaris 12 Potamogeton lucens13

Hypericum elodes 12 Potamogeton pectinatus23

Illecebrum verticillatum 1234 Ranunculus peltatus 1234

Imperata cylindrica 1 Ranunculus tripartitus 124

Lotus pedunculatus 13 Scirpus �uitans 2

Lotus subbi�orus 23 Zannichellia obtusifolia1

Lythrum junceum 1234

Mentha pulegium 1234

Myosotis ramosissima 1234

Panicum repens 1234

Paspalum paspalodes 1234

Ranunculus ophioglossifolius 1234

Rumex sp 34

Silene laeta 2

Other species with special conservation value collected in temporary ponds in Donana

Damasonium alisma Potamogeton natans Lemna trisulca

Ludwigia palustris Potamogeton polygonifolius Lemna gibba

Thorella verticillato-inundata Hydrocharis morsus-ranae Wolf�a arrhiza

Scorzonera �stulosa Callitriche regis-jubae Ricciocarpos natans

Callitriche lusitanica

as Myriophyllum alterni�orum and Callitricheobtusangula. In the deepest ponds, mainly thosewhich have been arti�cially deepened and watermay persist in small areas during the summer, itis possible to �nd macrophytes common in per-manent waters, such as Potamogeton lucens.

Fauna of the ponds

Zooplankton: Several previous studies haveshown that the temporary ponds of Donana sup-port a rich and dynamic community of zooplank-ton (Mazuelos et al., 1993; Fahd et al., 2000;


Serrano & Fahd, 2005). In total, over 150 zoo-plankton species have been listed in the Donanaponds: 78 micro-crustaceans (Fahd et al.,2009)and 74 rotifers (Garc�a-Novo & Mar�n, 2006).Besides many cosmopolitan species, there arealso species endemic to Donana, such as the ro-tifer Lecane donyanaensis (Galindo et al., 1994).A few other species are endemic to the IberianPeninsula-Balearic Isles, such as Daphnia hispa-nica (Alonso, 1996) while others have a restricteddistribution to SW Iberia, such as the copepodDussartius baeticus. More recently, some ex-otic crustacean species have been reported acrossDonana, such as the cladoceran Daphnia parvulain the freshwater ponds (Serrano & Fahd, 2005).

Macroinvertebrates: a total of 124 taxa ofmacroinvertebrates were recorded in the area (thecomplete list is given in Florencio et al. 2009)(Table 3). Among Coleoptera, we recorded 56taxa. Dytiscidae was the family that includedmore taxa (21 species). Hydrophilidae was alsoa diverse family, with at least 14 species. We de-tected species with special interest for conserva-tion, such as Coenagrion scitulum (Odonata: Co-enagrionidae) and Lestes macrostigma (Odonata:Lestidae) which are vulnerable species in theIUCN Red List (Verdu & Galante, 2005). Fourspecies of Coleoptera with a restricted distribu-

tion (North Africa and the Central and South ofthe Iberian Peninsula) were recorded: Hygrotuslagari, Hydroporus lucasi, Cybister tripunctatusafricanus and Lacobius revelieri. Of these, H. la-gari and H. lucasi were abundant and occurred inmost of the temporary ponds sampled. Other en-demic species for the Iberian Peninsula recordedin Donana temporary ponds were Haliplus an-dalusicus or Rhantus hispanicus.

The total number of macroinvertebrate taxarecorded per pond is shown in �gure 4. Mostof them occurred in 25-50 % of the ponds. Theponds with lower richness were those of shorterhydroperiod, which also included species whichwere not frequent in other types of ponds, thereforecontributing to increase the total richness in thearea (Fig. 4). For example, coleopterans Laccobiusrevelierei and Agabus dydimus were only foundin ponds with hydroperiod of less than 6 months.

Amphibians: Eleven of the total 13 species ofamphibians occurring in SW Spain are presentin Donana. Their abundance and distribution hasbeen described previously (D�az-Paniagua et al.,2005; 2006), as well as their breeding strategies(D�az-Paniagua, 1988; 1990; 1992), summarizedin table 4. Eight of the 11 species are typicalbreeders of temporary ponds, and are abundantor very abundant in the area; another species,

Figure 4. Cumulative number of macroinvertebrate taxa recorded in 18 temporary ponds monthly sampled during their �oodingperiod in 2006-07. Bars indicate the number of taxa detected in different percentages of the sampled ponds. The number of monthsthat ponds were �ooded is indicated in brackets after each pond name. Ponds have been ordered after decreasing richness. Numeroacumulado de taxones de macroinvertebrados registrados en 18 lagunas temporales, muestreadas mensualmente durante el periodode inundacion de 2006-07. Las barras indican el numero de taxones detectados en cada laguna, clasi�cados segun su aparicion enel porcentaje indicado de lagunas muestreadas. El numero de meses que cada laguna estuvo inundada se indica entre parentesis trassu nombre. Las lagunas se han ordenado en orden decreciente de riqueza espec��ca.


Table 3. Number of taxa of the different families and orders of macroinvertebrates recorded in the Donana ponds. The number ofdifferent genera and species recorded are also indicated, while – means that only the family or order could be identi�ed. Numero detaxones de macroinvertebrados registrados en las lagunas temporales de Donana. Se indica tambien el numero de especies y generosdiferentes registrados. Se indica – cuando solo se pudo identi�car hasta familia u orden.

Order Family N genera N species N taxa

Coleoptera 56Chrysomelidae 1 –Curculionidae 2 4Dryopidae 1 1Dytiscidae 15 21Gyrinidae 1 1Haliplidae 1 3Helophoridae 1 2Hydraenidae 3 5Hydrochidae 1 1Hydrophilidae 10 14Paelobiidae 1 1Noteridae 1 1Scirtidae 1 –

Heteroptera 19Corixidae 5 8Notonectidae 2 4Nepidae 1 1Pleidae 1 1Naucoridae 1 1Microveliidae 1 1Gerridae 1 2Saldidae – –

Odonata 16Libellulidae 2 5Lestidae 1 4Coenagrionidae 2 3Aeshnidae 3 4

Acari – – 1

Bassomatophora – 2Physidae 1 –Planorbidae – –

Decapoda 1Cambaridae 1 1

Diptera 16Ceratopogonidae – –Chaoboridae – –Culicidae – –Dixidae – –Chironomidae 3 1Dolichopodidae – –Ephydridae – –Rhagionidae – –Scatophagidae – –Sciomyzidae – –Syrphidae – –

Cont.


Table 3. (cont.)

Order Family N genera N species N taxa

Tabanidae – –Thaumelidae – –Tipulidae – –

Ephemeroptera 1Baetidae 1 –

Haplotaxida 2Lumbricidae & Sparganophilidae – –Tubi�cidae – –

Lumbriculida 1Lumbriculidae – –

Isopoda 1Asellidae 1 1

Notostraca 1Triopsidae 1 1

Anostraca 5Branchipodidae 1 2Chirocephalidae 1 1Streptocephalidae 1 1Tanymastigiidae 1 1

Conchostraca 2Cyzicidae 1 1Leptestheriidae 1 1

Pelophylax perezi mainly breeds in permanentwaters and in Donana is common only in thoseponds that have been arti�cially deepened topersist during the summer, therefore being ex-tended through different zones across the Park.The other two species are scarce or rare in thearea: Bufo bufo is restricted to the scarce perma-nent ponds, and Alytes cisternasii is restricted toa small area with streams to the North of the Park(D�az-Paniagua et al., 2006).

As a consequence of the wide differencesin rainfall, and in pond hydroperiod observedamong years (Fig. 2), temporary ponds also dif-fered in the number of breeding species. To il-lustrate this variation, we show the abundance ofthe amphibian larvae in three ponds with differ-ent hydroperiod in subsequent years of differentrainfall, including a dry year in which pondswere not �lled (2004-05) and amphibians didnot breed. In the pond with shortest hydroperiod,Bufo calamita wasthe predominant species in adry

year (2005-06), while in years of higher rainfallTriturus pygmaeus was predominant. In the in-termediate pond, Hyla meridionalis and T. pyg-maeuswere predominant in most of the years, butin the very rainy year (2003-04) Lissotriton bos-cai reached the highest abundances. In the pondof long hydroperiod we also detected differencesin species abundance, mainly in the two last yearswith predominance of Hyla meridionalis in 2005-06 and of Pelobates cultripes in 2006-07 (Fig. 5).

DISCUSSION

Donana National Park includes a high number ofponds which widely differ in their extent and hy-droperiod, con�guring a network of aquatic habi-tats. The characteristics of these ponds coincidewith the main description of Mediterranean tem-porary ponds (see Zacharias et al., 2007), as theyare formed on shallow depressions on sandy sub-


Figure 5. Relative abundance (number of larvae/total number of sampling units) of the amphibian larvae recorded in three ponds ofdifferent hydroperiod, sampled from 2002 to 2007 (In the dry year 2004-05 ponds were not �lled). A: pond of usually short hydrope-riod; B: pond of usually intermediate hydroperiod; C: extensive pond of usually long hydroperiod. Abundancia relativa (numero delarvas/numero total de unidades de muestreo de larvas de an�bios registrada en tres lagunas de diferente hidroperiodo, muestreadasentre 2002 y 2007 (no se inundaron en el ano de sequ�a 2004-05). A: lagunas que tienen normalmente un hidroperiodo corto; B: la-gunas que presentan normalmente un hidroperiodo intermedio; C: lagunas de amplia extension que habitualmente presentan unlargo hidroperiodo.

strate and show a wide variability in hydroperiod,and in the seasonal initiation of inundation. Someponds are mainly �lled by runoff water, whileothers, mainly those of longer water persistenceare also fed by groundwater (Garc�a Novo et al.,1991; Serrano et al., 2006; Gomez-Rodriguez etal., 2009). A comparison of their water chemistrywith other temporary ponds in MediterraneanRegion was made in Gomez-Rodriguez et al.(2009), being within the range of conductivityreported for Mediterranean temporary ponds in

Zacharias et al. (2007), similar to the ponds insouthern Portugal (Beja & Alcazar, 2003) and withlower pH and conductivity than ponds in southernFrance (Waterkeyn et al., 2008). Compared withother aquatic media of the same area, temporaryponds did not widely differ (Serrano & Toja, 1995;Serrano et al., 2006; Espinar & Serrano, 2009).

While temporary ponds are generally threat-ened aquatic habitats, which have been largelyunfavoured and often destroyed by human ac-tions to favour agriculture or urban development


(Williams et al. 2001; Grillas et al., 2004), thesystem of temporary ponds in Donana has beenpreserved under the integral protection of a Na-tional Park. The particular hydrology of this areaand the low human activities have favoured thepersistence of the smooth depressions onwhichwa-ter may temporally persist due to the presenceof high organic matter content and of semi-permeable horizons in their soils. These charac-teristics were related to the presence of a granu-lometrical discontinuity in depth, a Mio-Pliocenerelic horizon of semi permeable sediments withhigh iron content (Clemente et al., 1993) whichfavours the presence of a hanging water-table andcontributes through a feedback process to elon-gate the �ooding period, improves the clay-siltydeposit and increase the thickness of the organichorizon. In fact, the high number of ponds ofnatural origin that we describe for Donana hasnot been reported in other European areas, al-though many ponds of small size may have fre-quently been overlooked in ponds inventories, asalso were most temporary ponds in Donana inprevious studies (e.g. Bravo & Montes (1990)made an inventory of 308 ponds).

In Donana ponds, hydroperiod is conditionedby the timing and amount of rainfall within a par-ticular year, and even the year before during dryperiods (Serrano & Zunzunegui, 2008). Our dataillustrate the wide variation that ponds may expe-rience among years as the same pond may be ex-tensive and with a long hydroperiod during wetyears whereas it may become a short-durationpond in drier years. Moreover, locations shal-lowly �ooded in wet years may be completelydry in others, and therefore even the numberof temporary aquatic habitats is variable amongyears. This variation confers a temporal hetero-geneity to the area in which some years the samehabitat may be favourable for some species andother years may be unsuitable for these but ade-quate for others (Gomez-Rodr�guez et al., 2009).In view of such wide variations in pond waterpermanence, it is not possible to make a staticclassi�cation of the ponds regarding their dura-tion or hydroperiod, though classi�cations canbe assessed within the same year or makingreference to particular types of years.

Temporary ponds are important because they arespeci�c habitats for many organisms which donot survive in permanent ponds, including en-demic, rare or endangered species (Collinson etal., 1995; Grillas et al., 2004; Nicolet et al., 2004;Della Bella et al., 2008; Bilton et al., 2008). Theyare the main breeding habitats of most amphib-ian species in temperate areas (see e.g. Semlitsch,2003; Wells, 2007). While species richness maybe low in small ponds, the number of speciesassociated to these habitats increases with thenumber of ponds included in an area (Collinsonet al., 1995; Grillas et al., 2004). In this sense,the high number of ponds in Donana favoursthe conservation of a high number of species ofdifferent aquatic taxonomical groups. Regardingplant species, out of the 83 aquatic plant speciesrecorded in the area of Donana (Garc�a-Murillo etal., 2006; Fernandez-Zamudio et al., unpublisheddata), 68 were found in temporary ponds. About25 % of the species recorded are presently in-cluded in national or regional lists of threatened�ora with different IUCN categories (Cirujanoet al., 1992; Sergio et al., 1994; Banares et al.,2003; Cabezudo et al., 2005). Some examples areThorella verticillato-inundata, Lemna trisulca,Wol�a arrhiza,Zannichellia obtusifolia or Hydro-charis morsus-ranae. The latter is the most threat-enedspecies of our list and Donana maintains oneof the only two Spanish populations (Cirujano &Medina, 2002). The presence of these species andhabitats in European and National lists enhancesthe value of the Donana temporary ponds for theconservation of aquatic vegetation.

Regarding faunistic biodiversity, a high rich-ness of microcrustaceans, and rotifers has beenreported for Donana Ponds (Fahd et al., 2009).Most of these species were derived from severalsources, including tropical, Ethiopic, and North-African origins (Miracle, 1982), but also endemicspecies of special interest are included, being inthis area common or even abundant species. Alsoa high richness is found in macroinvertebratefauna. In the aquatic media of Donana, includ-ing the temporary ponds system, two permanentlarge ponds and the nearby marsh, 110 speciesof aquatic coleoptera have been reported (Millanet al., 2005), a richness similar or even higher


comparing with other temporary (Bazzanti et al.,1996; Schneider & Frost, 1996; Brooks, 2000;Boix et al., 2001) and permanent ponds (Heino,2000; Della Bella, 2005). Collinson et al. (1995)found that although a small number of specieswere characteristics of many temporary ponds,an ensemble of temporary ponds did not differin species richness from large permanent ponds.In our study area, also a similar increase in to-tal richness of macroinvertebrates and amphib-ians is observed when data from different tem-porary ponds are accumulated, in spite of the lowrichness of some small ponds.

Thus, some studies have claimed that for theconservation of biodiversity of temporary pondspecies, it is more important to preserve an areawith a system of temporary ponds, con�guringa network of ponds of different characteristicsand water regime that the preservation of isolatedlarge ponds (Oertli et al., 2002; Beja & Alcazar,2003; Cheylan, 2004; Angelibert et al., 2004;Zacharias et al., 2007; Bilton et al., 2008). In thissense, the temporary ponds system in DonanaNational Park may represent a good example of anetwork of aquatic habitats. The high number ofponds of different size experienced wide differ-ences in hydroperiod, within and among years,and the whole system has been proven to be a ro-bust network of breeding sites for amphibians inrainy years, and even in years of low annual rain-fall (Fortuna et al., 2006).

In this study we show the wide differencesthat may be observed among ponds in the num-ber and identity of amphibian species, whichare even increased in different annual periods.The annual period of inundation or hydroperiodof temporary ponds constrains the number ofspecies that a pond may include (Pechmann etal., 1989; D�az-Paniagua, 1992; Snodgrass et al.,2000), especially for those species with repro-ductive aquatic phases requiring a minimum pe-riod to be completed (as in this area the larvaeof some amphibian species, see D�az-Paniagua,1988). In general, amphibian fauna is well pre-served in the Donana National Park, and 11 ofthe 13 species of SW Spain are found in thisarea (D�az-Paniagua et al., 2006). This is mainlydue to the fact that most of the species are pond

breeders (D�az-Paniagua, 1990), and this areaprovides a wide availability of optimal breed-ing habitats. The system of temporary ponds ofDonana provides a wide heterogeneity of ponds,with different extent and duration, which is evenlarger at a longer temporal scale due to inter-annual differences in rainfall. For a same pond,hydroperiod will change in time, and conse-quently their dominant species, thus ponds maybe optimal habitats for different species in dif-ferent years (Semlisch, 2003), and these changesfavour the whole community in the long-term(see Gomez-Rodr�guez, 2009 for a detailed anal-ysis in this pond system). Similar arguments maybe extended to other faunistic species, such asmacroinvertebrates and zooplankton.

The Donana ponds represent an example ofconservation of temporary aquatic habitats becauseno single or isolated ponds are preserved, but awhole area with a high density and heterogeneityof temporary ponds. This system provides habitatsfor a wide number of plant and animal aquaticor semi-aquatic species, most of them unableto survive in permanent waters and many ofthemunder threat. This system has been indirectlypreserved due to the integral protection of a Na-tional Park, but as other temporary ponds systemis also presently threatened by several factors, asthe invasion of exotic species, and mainly by therisk of desiccation or hydroperiod shortening dueto overexploitation of ground water (Manzano& Custodio, 2006; Serrano & Zunzunegui, 2008;Serrano et al., 2008; Gomez-Rodr�guez, 2009). Aspeci�c management of the temporary pond sys-tem should be required to adopt particular mea-surements to prevent the present threats and topreserve such valuable habitats.

ACKNOWLEDGEMENTS

This study was funded by the Spanish Ministryof Science and Education and EU FEDER funds(CGL2006-04458/BOS) and Junta de Andaluc�a(Excellence Research Project RNM 932) and Fel-lowship grants CSIC-I3P (European Union So-cial Funds) to M.F. and AP-2001-3475 to C.G.-R.and JA-2003 to R.F.-Z., and JA-2005 to A.P.


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Effects of the intense summer desiccation and the autumn �lling onthe water chemistry in some Mediterranean ponds

Margarita Fernandez-Alaez & Camino Fernandez-Alaez∗

Department of Biodiversity and Environmental Management, Faculty of Biological and Environmental Sciences,University of Leon, 24071, Leon, Spain.2



ABSTRACT

Effects of the intense summer desiccation and the autumn �lling on the water chemistry in some Mediterranean ponds

The objective of this research was to compare the effects of evaporation and total desiccation, as well as the in�uence of therate of re�lling, on the concentrations of major ions and nutrients (nitrogen and phosphorus) in Mediterranean ponds. Waterlevel �uctuations in these ecosystems can have a decisive role in community structuring and functioning and may affect theirconservation values. The results obtained enable an assessment of the consequences of water quality changes resulting fromthe increased evaporation, drastic �uctuations in water levels and higher incidence of droughts in summer. Desiccation wasobserved to cause an increase in the bicarbonate and chloride concentrations, whilst sulphate content was frequently foundto have decreased. With respect to nutrients, a drastic reduction in water volume increased orthophosphate levels, with aconsequent drop in the N-nitrate: SRP ratio. Pond re�lling following total desiccation resulted in higher total anion content,especially among the waters with higher mineral content, the extent of which was related to the rate of re�lling. When re�llfollowed desiccation, sulphate concentrations increased the most, whilst alkalinity decreased in most ponds. An increase inchloride concentration was only observed when re�lling occurred slowly. Orthophosphate and nitrate concentrations increasedat the start of the re�lling period, although the most pronounced increase was in nitrate which, together with potassium, wasprobably washed into the ponds through soil leaching following autumn rainfall.

Key words: Ponds, ionic composition, nutrients, hydroperiod, evaporation, re�lling.

RESUMEN

Efectos de la intensa desecacion estival y del llenado otonal sobre la composicion qu�mica del agua de lagunas medi-terraneas

El objetivo de este estudio ha sido comparar los efectos de la evaporacion y la desecacion completa, as� como de la tasade llenado sobre las concentraciones de los principales iones y nutrientes (nitrogeno y fosforo) en un conjunto de lagunasmediterraneas. Las �uctuaciones del nivel del agua en estos ecosistemas pueden ser determinantes de la estructura y funcio-namiento de las comunidades y afectar a su conservacion. Los resultados obtenidos permiten hacer una valoracion de lasconsecuencias de los cambios en la calidad del agua derivados del aumento de la evaporacion, las drasticas �uctuacionesdel nivel del agua y la incidencia de las sequ�as estivales. En las lagunas estudiadas la desecacion causo un aumento de lasconcentraciones de bicarbonato y cloruro, mientras que fue habitual una disminucion del contenido de sulfato. Por lo quese re�ere a los nutrientes, la drastica disminucion del volumen de agua provoco un aumento de los niveles de ortofosfato,con la consiguiente disminucion de la relacion N-nitrato:P-ortofosfato. El llenado de las lagunas que siguio a la sequ�a totalcondujo a un aumento del contenido total de aniones, especialmente en las lagunas mas mineralizadas, que estuvo afectadoademas por el ritmo de llenado. Cuando la laguna se lleno rapidamente los mayores incrementos se produjeron en la con-centracion de sulfato, mientras que en la mayor�a de las lagunas disminuyo la alcalinidad. Cuando el llenado se produjolentamente se observo un aumento de cloruro. Las concentraciones de ortofosfato y nitrato aumentaron al inicio del periodode llenado, aunque el aumento mas destacado se registro en el contenido de nitrato, que junto con el potasio se incorporaronprobablemente a las lagunas a traves del lavado del suelo, que siguio a las precipitaciones de otono.

Palabras clave: Lagunas, composicion ionica, nutrientes, hidroperiodo, evaporacion, llenado.

60 Fernandez-Alaez & Fernandez-Alaez

INTRODUCTION

In Spain, and particularly in the North IberianPlateau, small ponds abound. Many of them aretemporary ponds, and they are considered aspriority habitats in the European Habitat Direc-tive. They have variable hydroperiods dependingon regional climatic conditions, making themextremely sensitive to climate as they dependmainly on rainfall. Given their dependence onrainfall and groundwater, these water bodies ex-perience marked �uctuations in water volume,contributing to create a signi�cant diversity ofhabitats, which support in turn a high biologicaldiversity. Fernandez-Alaez et al (2002) reporteda high �oristic richness for these ponds. In addi-tion, these small aquatic ecosystems have a signi-�cant diversifying effect in the landscape. In theMediterranean regions, �uctuations in the waterlevel of shallow water bodies are frequently theresult of natural processes (Fernandez-Alaez etal., 2004; Alvarez-Cobelas et al., 2005; Beklio-glu et al., 2007), with inter- and intra-annual va-riations imposed by climatic conditions and bythe impact of human activity (Blindow, 1992;Gafny and Gasith, 1999). Water level �uctuationsin these ecosystems can have a decisive role incommunity structuring and functioning and mayaffect their conservation values. The temporaryponds are often highly unpredictable, alternatingdry and wet phases of varying length from oneyear to the next, according to the amount of rain-fall. Thus, over a complete annual hydrologic cy-cle, a marked contrast can be observed betweenwet periods (autumn and spring) when pond re�lloccurs, and periods of intense evaporation (sum-mer) which produce a negative water balance.Furthermore, the small size and shallowness ofthese water bodies makes them highly vulnerableto small �uctuations in the variables controllingtheir hydrological regime.

Hydrological variability is frequently re�ec-ted in chemical variability (Com�n and Williams,1994; Tan and Beklioglu, 2005; Williams, 2006).Vangenechten et al., (1981) studied the physico-chemical properties of moor land pools in rela-tion to changes in water availability as a conse-quence of climatic conditions, and Meintjes et al

(1994) analysed changes to certain physicoche-mical parameters in small seasonal pans in re-lation to �ooding duration. However, in spite ofthese studies, information on the effects of hydro-logic variations on physicochemical conditions isscarce, and even more so in relation to small wa-ter bodies in the Mediterranean region.

The fundamental objective of this study wasto investigate how the chemical characteristics ofwater bodies are affected by two situations whichare commonly experienced by all Mediterraneanponds: summer desiccation and autumn refilling.The results obtained enable an assessment to bemade of the consequences of water quality changesresulting from the increase evaporation, drasticfluctuations in water levels and higher incidenceof droughts in summer, all of which are predictedby models of climatic change (Coops et al., 2003;Alvarez-Cobelas et al., 2005; Noges et al., 2007).An analysis of the effects of hydrological va-riations on the chemical characteristics and qua-lity of water is an applied question of climaticchange, the results of which are still uncertain.


Study area

Research was carried out on 13 ponds locatedin north-western Spain, in a relatively homoge-neous landscape consisting of �atlands lying bet-ween 750 and 950m above sea level. Seven of theponds studied are temporary (Table 1) and thelength of their hydroperiod depends on rainfall,which usually peaks in autumn and spring. Six ofthe ponds are permanent, but experience a severereduction in water volume during the summer.

The ponds are shallow (maximum depth200 cm) and not very big (0.6-3 ha) except forone (of 16 ha), and are fed by a combinationof groundwater and rainfall (Fernandez Alaezet al., 2006). Most of the ponds are surroundedby agricultural fields. Their main characteristicsare presented in Table 1.

The area possesses a Mediterranean climatewith hot dry summers and cool rainy winters(mean temperature in July is 20 ◦C and mean

Effects of evaporation and desiccation on water chemistry 61

Table 1. Morphometric and geographical characteristics and water permanence in the studied ponds (T: temporary, P: permanent).Caracter�sticas morfometricas, geogra�cas y de permanencia del agua en las lagunas estudiadas (T: temporales, P: permanentes).

Ponds Altitude (m) Area (Ha) Maximun Depth (cm) Persistence

01-Espino 900 01.70 100 T02-Monte 870 00.60 100 T03-Valdepolo 925 01.20 100 P04-Estorrubio 900 00.80 150 T05-Melgan 789 02.20 150 P06-Del Redos 900 01.00 180 P07-Rey 860 02.50 200 P08-Sta. Cristina 800 00.05 200 P09-Balastrera 800 02.70 150 T10-Grande 830 16.20 200 P11-Villamarco 840 01.70 150 T12-Mayor 840 00.60 100 T13-Seca 810 03.00 200 T

annual precipitation, 533 mm). The dominantlithology in the study area consists of low-thick-ness post-Tertiary deposits (“ranas” and alluvialterraces) which superficially cover the greatTertiary detritic deposits.

Sampling and analysis

Water samples were taken seasonally (May 1994,July 1994, November 1994, February 1995, May1995, July 1995, November 1995 and February1996) at a sampling station situated in the cen-tre of each pond. At the same time, depth in thesampling station was measured in order to checkwater level changes. The following parameterswere measured in situ: temperature, dissolvedoxygen and its saturation percentage, conducti-

vity and pH, using a GRANT/YSI “Water Qua-lity Logger 3800” measurement system. Sampleswere also collected at each pond for chemicalanalysis. In the laboratory, the following analy-ses were carried out on water samples: total al-kalinity by titration with sulphuric acid (APHA,1989); sulphate by turbidimetry (APHA, 1989);chloride using selective electrode; calcium, mag-nesium, sodium and potassium with InductivelyCoupled Plasma Spectrometry (ICP); N-nitrateby reduction to nitrite on spongy cadmium andspectrophotometric measurement (Mackereth etal., 1978); N-ammonium by indophenol blue for-mation and spectrophotometry (APHA, 1989);and P-orthophosphate (SRP) using molybdenumblue formation and spectrophotometric determi-nation (Murphy and Riley, 1962).

Table 2. Depth values (cm) in the studied ponds measured seasonally in the sampling station. Valores estacionales de profundidad(cm) medidos en la estacion de muestreo.

Ponds Sp94 Su94 Au94 Wi95 Sp95 Su95 Au95 Wi96

01-Espino 60 10 00 37 00 00 35 07002-Monte 65 30 00 20 00 00 00 07403-Valdepolo 62 40 10 49 37 20 40 06504-Estorrubio 60 10 00 29 00 00 38 07005-Melgan 70 35 50 60 40 00 50 10006-Del Redos 75 37 54 70 45 00 52 08007-Rey 90 39 65 73 40 15 56 20008-Sta. Cristina 70 45 65 70 42 00 00 08009-Balastrera 60 20 51 63 35 00 55 07510-Grande 72 45 23 65 37 00 21 07011-Villamarco 54 00 26 64 28 00 50 06012-Mayor 60 35 43 61 35 00 00 06013-Seca 54 10 15 51 32 00 00 080


Data Analysis

Pearson’s correlations were performed to �ndcross-correlations among the different ions andbetween these and conductivity. In addition, aPrincipal Component Analysis (PCA) was ca-rried out using the following water physicoche-mical characteristics: pH, oxygen, conductivity,total alkalinity, sulphate, chloride, calcium, mag-nesium, sodium, potassium, nitrate, ammoniumand orthophosphate.

For both analyses, the Kolmogorov-Smirnovtest was used to check the normality of the varia-bles and, where necessary, data were log trans-formed (log x + 0.001).

Statistica 6.0 was used for univariate analy-ses and the multivariate analysis was carried outusing the software CANOCO v.4.5.

RESULTS

Precipitation levels in the study area for theperiod January 1994-March 1996 were extre-mely variable, with signi�cant seasonal and inter-annual differences. There was abundant rainfallin the spring of 1994, reaching a total of 100 mmin May, followed by a sharp decrease during thesummer months, with a minimum of 3.9 mm inJuly. Nevertheless, practically all the ponds retai-

ned some water throughout the summer, althoughwith greatly reduced volume. By the end of sum-mer, however, the majority of the ponds weredry, and some even remained dry into the autumn(Table 2). Although they later re�lled with water,precipitation levels were not high, and these sa-me ponds were the �rst to dry up in the followingspring. Precipitation levels were extremely low inthe spring of 1995, with a minimum of 7.4 mm inMarch 1995. Low rainfall caused a considerablereduction in the water level entering the ponds,with the result that the majority of them becamedry that summer (Table 2). Some ponds even be-came dry in the spring, and others continued tobe dry well into the autumn. Although autumnrains contributed to pond re�ll, their water levelremained low during this season. Thus, two pe-riods of intense evaporation (summer 1994 andspring 1995), and two periods of desiccation (theend of summer 1994, and summer 1995) were re-corded for the ponds. In all cases, the ponds werelater re�lled by autumn precipitations

Table 3 gives the mean values and variationrange for conductivity and total anion content in theponds studied. In general, total anion concentrationand conductivity ranges at each pond were wide,especially in ponds with high mineral content.

In the principal component analysis carriedout on all pond samples collected between spring1994 and winter 1996, axes 1 and 2 explain 41%

Table 3. Means and range of variation of conductivity and total anion content in the studied ponds. Valores medios y rangos devariacion de la conductividad y del contenido total de aniones en las lagunas estudiadas.

Ponds Total anions (meql−1) Conductivity (uScm−1)

Mean Range Mean Range

Espino 03.07 01.27-4.63 0289 0142-378Monte 03.22 01.81-6.24 0337 0182-650Valdepolo 04.38 1.45-10.19 0409 0116-894Estorrubio 04.68 01.47-8.87 0396 0158-598Melgan 05.24 03.11-6.90 0460 0280-584Del Redos 05.88 02.44-9.77 0540 0240-888Rey 06.12 1.54-18.66 0459 164-1083Sta. Cristina 06.15 2.91-17.85 0537 266-1478Balastrera 07.67 5.25-14.94 0676 338-1308Grande 11.31 3.51-27.96 0844 322-1614Villamarco 11.68 4.40-17.98 0960 384-1508Mayor 16.59 2.67-48.44 1469 198-3860Seca 25.47 2.11-85.55 1847 188-5750


and 14.2% of the variation, and had eigenvaluesof 0.41 and 0.14 respectively.

The main gradient identi�ed with PCA wasrelated to changes in the ionic concentration, ba-sically associated with chloride and all the ma-jor cations except potassium. Moreover, the se-cond axis established a tendency related to pHand oxygen, although sulphate, nitrate and po-tassium also showed a high negative correlationwith this axis. The positive extreme of axis 2 wasde�ned by alkalinity (Fig. 1).

Effects of intense evaporation on the chemicalcharacteristics of the water

The reduction of water volume due mainly toevaporation in summer 1994 and spring 1995caused a substantial increase in the total ion con-centration in the ponds (Table 4). On average,the total anion concentration increased 1.4-foldin summer 1994 and 1.2-fold in spring 1995. Inseveral ponds, the total concentration of anionsincreased about 2-fold. The most extreme exam-

-0.6 1.2

-1.0

1.0

N-Nitrate

P-Phosphate Calcium

Magnesium

Sodium

Potassium

Chloride

Conductivity

Alkalinity

Sulphate

pH

Oxygen

N-Ammonium

55

5

5

5

5

5

8

8

8

8

8

8

12

12

12

12

12

12

2

2

2

2

7

7

7

7

7

7

7

33

3

3

33

3

4 4

4

4

4

6

6

6

6

6

66

1

1

1

1

1

13

13

13

13

13

13

9

9

99

8

9

9

11

11

11

11

11

11

10

10

10

10

10

1010

Figure 1. PCA ordination diagram of 1st and 2nd axes obtained from 13 water variables and 46 samples. Numbers iden-tifying ponds are those used in table 1. Spring 1994, Summer 1994, Autumn 1994, Spring 1995, Summer 1995,Autumn 1995, Winter 1996. Diagrama de ordenacion ACP (ejes 1 y 2) obtenido a partir de 13 variables f�sico-qu�micas y

46 muestras. Los numeros que identi�can a las lagunas se recogen en la tabla 1. Primavera 1994, Verano 1994, Otono 1994,Primavera 1995, Verano 1995, Otono 1995, Invierno 1996.


ples were recorded for those ponds still holdingwater although with very low levels, in summer1995 (Rey and Valdepolo). The anion concentra-tions at these ponds were four times higher in thesummer than in the previous winter.

In both 1994 and 1995, bicarbonate and es-pecially chloride were involved in rising mine-ral concentration due to decreasing water levels(Table 4). In several ponds, chloride concentra-tions practically doubled, and in the most ex-treme example, tripled (1.2 meq l−1-3.9 meq l−1)between the spring and summer of 1994. Withregard to this result, the correlation betweenconductivity and chloride increased from 0.59( p = 0.070) in winter 1995 to 0.74 ( p = 0.014) inspring 1995. The increase in bicarbonate was notso generalised. On the other hand, sulphate levelsgenerally fell to a varying extent in all ponds, es-pecially in summer 1994 (Table 4).

At the time of highest water level, during thespring of 1994, the predominant anions were bi-

carbonate and chloride, constituting an averageof 46% and 38% of total anion concentration,respectively. In winter 1995, most ponds showedsimilar percentages of three major anions as a re-sult of a rise in sulphate levels the previous au-tumn. Throughout both annual cycles, the pre-dominance of bicarbonate and chloride rose, andsulphate levels fell, as water level reduced. Thiseffect was especially the case in summer 1994,when sulphate constituted less than 10% of totalanion concentration in practically all the ponds,whereas during the spring values typically ran-ged between 20% and 30% (Fig. 2).

With respect to the cations, evaporation prin-cipally affected sodium concentrations, with 1.4-fold average increase, and a general rise in mag-nesium levels was also noticed (Table 4). Thesechanges were seen in ponds with both high andlow mineral contents. In several ponds, magne-sium concentrations doubled, whilst sodium con-centrations increased 3.7-fold (from 0.43 meq l−1

Table 4. Means and range of variation of ions and nutrients in spring and summer 1994 and winter and spring 1995 in the studiedponds. Valores medios y rangos de variacion de iones y nutrientes en primavera y verano de 1994 y en invierno y primavera de 1995en las lagunas estudiadas.

Spring 1994n = 12

Summer 1994n = 12

Winter 1995n = 10

Spring 1995n = 10

Total anions (meq l−1) Mean 4.96 7.16 7.94 9.33Range 2.34-11.50 2.46-21.10 2.94-13.00 3.01-19.54

Alkalinity (meq l−1) Mean 2.29 3.66 2.73 3.24Range 0.33-4.17 0.79-10.45 0.70-6.47 0.56-7.00

Chloride (meq l−1) Mean 1.76 3.01 2.75 4.24Range 0.71-4.48 0.78-8.43 1.03-4.77 0.70-11.39

Sulphate (meq l−1) Mean 0.92 0.49 2.45 1.85Range 0.03-3.07 0.02-2.21 0.29-5.06 0.02-6.12

Calcium (meq l−1) Mean 2.32 2.79 3.55 2.91Range 1.01-4.46 1.14-6.55 1.26-5.70 1.03-5.78

Magnesium (meq l−1) Mean 1.22 1.38 1.61 1.97Range 0.38-2.37 0.49-3.96 0.33-3.15 0.53-4.42

Sodium (meq l−1) Mean 1.15 1.62 1.72 2.41Range 0.43-3.46 0.42-6.36 0.61-3.99 0.41-7.42

Potassium (meq l−1) Mean 0.17 0.15 0.24 0.25Range 0.04-0.18 0.00-0.46 0.07-6.47 0.05-0.61

P-Phosphate (µg l−1) Mean 8.69 13.76 6.93 82.10Range 0.00-53.21 2.23-68.23 0.15-15.77 6.26-531

N-Nitrate (mg l−1) Mean 0.69 0.77 1.17 1.25Range 0.30-1.41 0.26-2.48 0.29-2.29 0.50-2.08

N-Ammonium (µg l−1) Mean 92 292 82 165Range 0.00-33 16.10-3100 8.30-201 37.50-404


0%

20%

40%

60%

80%

100%

SP-94 SU-94 WI-95 SP-95

Alkalinity Chloride Sulphate

0%

20%

40%

60%

80%

100%

SU-94 AU-94 SP-95 AU-95

0%

20%

40%

60%

80%

100%

SU-94 AU-94 SP-95 AU-95

0%

20%

40%

60%

80%

100%

SP-94 SU-94 WI-95 SP-95

Calcium Magnesium Sodium Potassium

A B

Figure 2. Mean percentage of anions and cations (for meql–1 data) in each season ordered to show: A) Effect of intense evaporation.B) Effect of drought and the subsequent re�lling. Porcentaje medio de aniones y cationes (con datos en meql–1) en cada estacion delano ordenados para mostrar: A) Efecto de la evaporacion intensa. B) Efecto de la sequ�a y posterior llenado.

in spring to 1.6 meq l−1 in summer 1994). Theincrease in the correlation between sodium andconductivity from 0.58 ( p = 0.08) in winter 1995to 0.93 ( p = 0.0001) in spring 1995 was indi-cative of the greater implication of chloride inthe mineral concentration of the waters. Calciumand potassium levels rose in a smaller number ofponds, and in many cases they even fell (Table 4).Signi�cant decreases of calcium concentrationswere associated with pH increases. In spite ofthese changes, calcium remained the predomi-nant cation in all ponds (Fig. 2).

With regard to nutrients, there was a markedincrease in orthophosphate concentrations duringthe decrease of the water volume in summer(Table 4). This increase was recorded for almostall of the ponds, and was most pronounced duringthe 1995 period of desiccation, multiplied by afactor between 1.7 and 47 with respect to con-

centrations recorded for winter. The maximumorthophosphate concentration increase was from15.8 µg l−1 in winter to 531 µg l−1 in spring 1995.Unlike orthophosphate, increases in nitrate con-centrations during the period of desiccation we-re of a lesser magnitude (Table 4). Nevertheless,in some ponds nitrate concentrations increased2-fold, from 1.1 to 2.4 mg l−1 and from 0.71 to1.44 mg l−1. On the other hand, ammonium con-centrations rose markedly in nearly all the ponds,increasing by a factor of up to 50. This coinci-ded with a pronounced decrease in oxygen le-vels at the bottom, with values ranging between0.9 mg l−1 and 2.9 mg l−1.

The marked increase in orthophosphate levelsduring the spring of 1995 brought about a mo-re than 10 fold reduction in N-nitrate:SRP ratio(in mass) in practically all the ponds, with meanvalues of 890 in winter and 82 in spring.


Pond ordination within the space de�ned by the�rst two PCA axes summarised the changes ob-served in ion composition and nutrient contentdue to desiccation. For spring 1995 samples and,above all, summer 1994 samples, displacementtowards the positive extreme of axis 2 was ob-served compared to samples from previous pe-riods (Fig. 1), fundamentally as a result of thereduction in sulphate and increase in bicarbo-nates. Likewise, some samples re�ecting the ef-fect of intense evaporation, especially those fromthe ponds with higher mineral contents, tendedto occupy a position towards the extreme end ofhigh ionic concentration, associated with chlori-de (the extreme positive end of axis 1) (Fig. 1).This position also re�ected a positive relationwith phosphate and ammonium, and a negativerelation with oxygen concentration.

Effects of drought and the subsequent re�llingof the ponds on the chemical characteristics ofwater

In most ponds that dried out completely du-ring the summer time, re�lling in the autumnof 1994 resulted in increased ion concentrations(Table 5), with greatest changes being observedin the ponds with higher mineral content, wheretotal anion concentrations multiplied by a factorbetween 1.2 and 5. In ponds with a lower mine-ral content this tendency was not so marked, andin some cases a slight reduction in ion concentra-tions was registered. On average, total anion con-centration increased 3-fold, and in the most ex-treme case increased 5-fold, from 3.5 meq l−1 to17.8 meq l−1. As it would be expected from theseresults, conductivity increased on average by 2.4,

Table 5. Means and range of variation of ions and nutrients in summer and autumn 1994 and spring and autumn 1995 in the studiedponds. Valores medios y rangos de variacion de iones y nutrientes en verano y otono de 1994 y primavera y otono de 1995 en laslagunas estudiadas.

Summer 1994

n = 9

Autumn 1994

n = 9

Spring 1995

n = 7

Autumn 1995

n = 7

Total anions (meq l−1) Mean 7.78 23.75 8.10 8.95

Range 2.89-21.10 3.11-85.55 3.82-16.90 2.73-18.66

Alkalinity (meq l−1) Mean 4.13 3.11 3.27 2.25

Range 1.09-10.45 0.29-13.89 0.56-7.00 0.09-5.94

Chloride (meq l−1) Mean 3.11 9.11 3.81 2.84

Range 0.78-8.43 0.81-35.25 1.52-8.60 0.78-4.50

Sulphate (meq l−1) Mean 0.55 11.53 1.01 3.86

Range 0.02-2.21 0.34-48.05 0.02-2.15 1.46-11.53

Calcium (meq l−1) Mean 2.98 10.30 2.69 4.58

Range 1.33-6.59 1.14-6.55 1.45-5.15 1.58-8.12

Magnesium (meq l−1) Mean 1.66 4.49 1.76 1.62

Range 0.49-3.96 0.64-16.41 0.54-4.43 0.39-2.63

Sodium (meq l−1) Mean 1.81 4.55 1.67 1.35

Range 0.42-6.36 0.46-18.01 0.82-3.90 0.64-2.71

Potassium (meq l−1) Mean 0.11 0.58 0.22 0.37

Range 0.00-0.46 0.14-1.81 0.05-0.61 0.10-1.28

P-Phosphate (µg l−1) Mean 16.27 36.74 32.86 61.47

Range 2.23-68.23 5.70-258 6.26-146 0-334

N-Nitrate (mg l−1) Mean 0.87 2.28 1.15 9.03

Range 0.44-2.40 0.39-9.51 0.50-1.44 0.29-24.70

N-Ammonium (µg l−1) Mean 37.60 407 156 561

Range 16.10-78.40 15.40-2260 37.50-404 9.30-3470


with a maximum value of 5750 µS cm−1, whe-reas previous to desiccation, highest pond con-ductivity was 1930 µScm−1. These results can beseen in the pond ordination diagram, where au-tumn 1994 samples, especially those from waterswith high mineral content, tend to occupy posi-tions on the positive end of axis 1 (Fig. 1).

During the second annual cycle, desicca-tion and the subsequent re�lling of the pondsdid not result in a general rise in total anionconcentration, and mean overall values for theponds in spring and autumn 1995 were 8.10 and8.95 meq l−1 respectively (Table 5). Neither wasthere a general increase in conductivity, withmean values for before and after desiccationbeing 679 and 615 µS cm−1 respectively.

Sulphate concentration was especially affec-ted by re�lling following desiccation, showingan increase across all the ponds both in autumn1995 and autumn 1994. This increase was espe-cially pronounced in autumn 1994, with concen-trations registered in the summer increasing bya factor of between 2 and 600. Moreover, du-ring re�ll the correlations between sulphate andall cations increased with respect to values recor-ded before drought (Table 6). Chloride levels, ho-wever, were only affected by autumn 1994 waterre�ll, when concentrations rose by a factor of bet-ween 1.2 and 5. For both annual cycles, a markedreduction in alkalinity was observed at the startof the re�lling period, in autumn, as comparedto values recorded before desiccation (Table 5)and the correlations between alkalinity and all ca-tions decreased (Table 6). Moreover, the desicca-tion and the subsequent re�lling of the ponds in-

duced changes in the percentages of anions.Priorto desiccation, bicarbonate and chloride constitutedthe predominant ions in most ponds. However, atthe start of the refilling sulphate and in some cases,chloride became the predominant anions inmanyofthe ponds, with bicarbonate providing the smallestcontribution to total ionic concentration (Fig. 2).

The effect of refilling on cation concentrationswas different for each of the annual cycles. Inautumn 1994, cation concentrations increased inpractically all of the ponds (Table 5). In general,the most significant change was recorded forpotassium, with pre-desiccation values multiplyingby a factor of between 1.5 and 30 at the start ofthe refilling. Calcium continued to be the dominantcation in the ponds, whilst potassium representedthe lowest percentage, with values of between 2%and 19% (Fig. 2). In autumn 1995, increases weremainly recorded for calcium and potassium,whilst changes to sodium and magnesium le-vels were variable (Table 5). Calcium continuedto be the dominant cation in the ponds, whilstthe proportion of magnesium and sodium decrea-sed. The cation contributing least to total mineralconcentration continued to be potassium (Fig. 2).

As for nutrients, orthophosphate concentra-tions increased during autumn re�lling (Table 5).The extent of the increase varied among theponds; in the most extreme case, the orthophos-phate concentration multiplied by a factor of 226,reaching a level of 259 µg l−1. Likewise, nitra-te concentrations rose considerably, but unlikeorthophosphate, this increase affected practica-lly all the ponds during both re�lling periods,with increases by a factor of between 1.5 and 20.

Table 6. Cations-sulphate and cations-alkalinity correlations before and after pond drought (S: Summer, A: Autumn, Sp: Spring) (*p< 0.05, ** p< 0.01, *** p< 0.001). Valores de correlacion entre cationes y sulfato y entre cationes y alcalinidad antes y despuesdel periodo seco (S: verano, A: otono, Sp: primavera) (* p< 0.05, ** p< 0.01, *** p< 0.001).

S-94

n = 9

A-94

n = 9

Sp-95

n = 7

A-95n = 7

S-94

n = 9

A-94

n = 9

Sp-95

n = 7

A-95n = 7

Alkalinity (meq l−1) Sulphate (meq l−1)

Calcium (meq l−1) 0.96*** −0.07 0.64 0.30 0.90*** 0.99*** −0.14 0.80*

Magnesium (meq l−1) 0.89** 0.21 0.80** 0.40 0.76* 0.92*** 0.73 0.70

Sodium (meq l−1) 0.91*** 0.11 0.44 0.14 0.96*** 0.91*** 0.56 0.93**

Potassium (meq l−1) 0.78* 0.77* 0.41 −0.41 0.62 0.43 0.59 0.90**


The increase in nitrogen concentrations was morepronounced in autumn 1995 (Table 5), reachingmaximum concentrations of 24.7 mg l−1, compa-red with maximum concentrations recorded inthe summer of 1.97 mg l−1.

In general, the N-nitrate:SRP ratio increasedat the beginning of the �ood periods. However,this increase was notably more pronounced inautumn 1995, with the N-nitrate:SRP ratio mul-tiplying by a factor of up to 83, and affectinga greater number of ponds.

In PCA ordination of the ponds, the increase insulphate, potassiumandnitrate during flood periodswas a determining factor behind the displacementof the majority of autumn samples towards thelower right quadrant of the PCA plot (Fig. 1).

DISCUSSION

Hydrological variations determined changes inthe ionic concentrations and composition in thenorth-western Spanish ponds studied. Pond sa-linity and major ion levels proved to be veryvulnerable to evaporation and �ooding followingdesiccation. Williams (2006) has indicated thatthese processes are responsible for changes in theconcentration and relative abundance of dissol-ved substances in temporary water systems.

Various authors (Malmer, 1962; Cole, 1968;Vangenechten et al., 1981; White et al., 2008)have reported ion concentration changes during�uctuations in aquatic system water levels, andsigni�cant increases in mineral content measu-red via conductivity when the water level under-goes a drastic reduction due to evaporation (Co-le, 1968; Rodrigo et al., 2002; Camacho et al.,2003; Garc�a-Ferrer et al., 2003). For example,Tan (2002) reports that in two shallow lakes in anarid region of Turkey, salinity levels rose drasti-cally in response to drier hydrological conditions.

The low precipitation and intense evaporationwhich the majority of ponds in north-westernSpain underwent in the summer of 1994 andspring of 1995 produced signi�cant increases inion concentration and conductivity. In contrast tothe results reported by Vangenechten et al (1981)on acidic moorland ponds in Belgium, this dras-

tic reduction in water volume did not, however,have the same effect on anions. As chloride isthe last ion species to precipitate in conditionsof evaporation, this anion and sodium constitutedthe two ions most closely involved in an increa-se in mineral content in the Spanish ponds stu-died. This is demonstrated by the fact that as eva-poration caused the concentration of dissolvedions, the correlation with conductivity for bothions also increased. In contrast, other, less solublesalts such as calcium sulphate were more inclinedto precipitate, with the consequent loss of bothion species during evaporation. Cole (1968) hasindicated that this process of precipitation is a ty-pical change in water chemistry when concentra-tion occurs due to evaporation. The loss of cal-cium was compensated for by a relative increasein magnesium and sodium (Cole, 1968).

In addition, as reported by Patrick and Wyatt(1964), changes to pond hydrology affected nu-trient cycles in the ponds studied. Although nitra-te concentrations rose in some ponds, an increasein ammonium was both more frequent, this lat-ter being favoured by the predominant reductionconditions present at the pond bottom. Likewi-se, desiccation produced a noticeable increase inorthophosphate, leading to situations of markedeutrophy. Various processes may have been in-volved in the chemistry of this nutrient. Firstly,calcium does not appear to have been decisi-ve in controlling concentrations of bio-availablephosphorus in this study, a question which hasbeen discussed by several authors (Sondergaardet al., 1996; Hupfer et al., 2000). It would bereasonable to expect that in hard waters, phos-phorus levels would be reduced through incorpo-ration into precipitated calcium carbonate. Ho-wever, in some of the ponds, included in thisstudy, with high photosynthetic activity, althoughpH rose to over 9 with the consequent decrea-se in calcium, this did not result in a loss of or-thophosphate. In the present case, a more relia-ble explanation would be that low water levelprovided longer contact with sediment, contribu-ting to internal release of phosphorus (Karapinar,2005; Romo et al., 2005). In addition, the predo-minant reduction conditions present in the pondsediment would have favoured the liberation of


orthophosphate and, consequently, a pronouncedincrease in orthophosphate concentrations in thewater column. Those ponds showing the mostpronounced increase in this nutrient were charac-terised by having pond �oor oxygen concentra-tions of less than 1 mg/l (<10% saturation).

The changes to nutrient concentrations produ-ced during periods of desiccation also affectedN-nitrate:SRP ratio values, with a decrease whichwas especially pronounced in spring 1995. Thesevariations have important biological implications,especially for the phytoplanktonic communities, asthe N:P ratio is considered a fundamental factorin the predominance of cyanobacteria in warmlakes (Smith, 1983; Shapiro, 1990). For exam-ple, in a mesocosm experiment carried out ata small shallow Mediterranean lake in north-western Spain (Fernandez-Alaez et al., 2004), thepredominance of a cyanobacterial Mycrocystisbloom was correlated with a low DIN:SRP ratio.

In Mediterranean regions, many shallow wa-ter bodies become completely or partially dryduring the summer and even towards the endof spring. It is to be expected that this desic-cation and posterior �lling would have a signi-�cant effect on water chemistry (Jeffries et al.,2002; Tipping et al., 2003; Williams, 2006). Astemporary water systems desiccate, organic mat-ter located in the top sediment layer is oxidised,and evaporation at the sediment-water interfacecauses an upward �ow of water containing thedissolved compounds (De Groot and Golterman,1994). Thus, it is reasonable to expect changes tothe chemical composition of water after �ooding.

In the ponds studied in the northwest of Spain,summer droughts produced changes in the ionicconcentrations and composition at the beginningof the flood periods although the results obtainedappear to indicate that the rate of refill is decisive.When the ponds refilled slowly, such as in autumn1994, a sharp increase in ion concentrations andconductivity was recorded, which was more pro-nounced in the waters with high mineral contentwaters. However, when re�ll occurred rapidly, aswas the case following heavy rainfall in autumn1995, ion concentrations in the majority of theponds did not increase, and in some cases evendiminished as a result of salt dilution processes.

After �ooding, large concentrations of sulphatewere measured in the water. This finding has alsobeen recorded by other authors (Vangenechten etal. 1981; Eimers and Dillon, 2002; Eimers et al.,2007), and is basically understood to be the resultof oxidation of reduced S compounds, causedby the exposure of anoxic sediment to the airduring drought (Malmer, 1960, 1962; Eimers etal., 2007). Therefore, the level of sulphate concen-trations in these water systems is influenced bysummer drought (Eimers & Dillon, 2002; Eimerset al., 2004), and highest concentrations willbe recorded during years of prolonged summerdrought. The increase in correlations betweensulphate and all cations during �ooding leads tothe conclusion that the excess of this anion in thewater at the start of the re�lling period was coun-teracted by all cations. In contrast, bicarbonateimplication in cation chemistry diminished, es-pecially with regard to calcium and magnesiumchemistry, and a reduction, or even absence, ofsigni�cant correlations was observed.

The in�uence of drought on chloride levelswas not as evident as for sulphate levels, re�ec-ting the �ndings of Wangenechten et al (1981)in their study of pools in Belgium, where chlori-de was not found to increase with low water le-vels during �ooding. In the present study, it wasonly when re�lling occurred slowly (as in au-tumn 1994) and pond water levels were low thatan increase in chloride concentration was obser-ved. This was probably related to sediment mobi-lisation processes given that chloride and sodiumare the �rst ions to be dissolved after rainfall(Espinar and Serrano, 2009).

Slower pond re�lling following desiccationfavoured a general increase in all cations. Howe-ver, when this process occurred more quickly,only calcium and potassium were responsive tohydrologic variations. The increase in potassiumwas especially pronounced, regardless of thepond re�ll rate, and was probably linked to soilrunoff following autumn rainfall. This input ofallochthonous potassium is favoured by the factthat all the ponds are located in a predominantlyagricultural landscape where the potassium addi-tion to soil is common practice. In spite of thesechanges, the cation order of dominance did not


vary, and calcium remained the predominant ca-tion in all the ponds.

High concentrations of nitrogen and phospho-rus were recorded in the ponds during autumn re-�lling in 1994 and 1995, showing a considerableincrease on levels recorded prior to desiccation.Rodrigo et al (2002) obtained similar results forshallow ponds in eastern Spain; in addition, thereis evidence related to rice�elds, ecosystems sub-ject to alternative processes of desiccation and�ooding, indicating that �ooding releases signi-�cant quantities of nutrients, such as nitrogen inthe forms of nitrate and ammonium (Fores andCom�n, 1987; Fores and Sabater, 1987; Com�nand Fores, 1990). In the case of phosphorus, va-rious studies have found that high concentrationscoincide with �ooding after desiccation (Baldwinand Mitchell, 2000; Newman and Pietro, 2001;Young and Ross, 2001). The results of our studycan be explained by the fact that pond desiccationwould have accelerated the rate of organic ni-trogen and phosphorus mineralisation (Gerritsenand Greening, 1989; Song et al., 2007), and the-se nutrients would then have been released fromthe sediment into the water during �ooding. Inaddition, in the case of phosphorus, some authorshave reported a desorption process of phosphatepreviously adsorbed in crystalline minerals, re-leasing it into the water during re�lling (Song etal., 2007). As for nitrate, the heavier rainfall ofautumn 1995, with the subsequent soil leaching,was probably a determining factor in nitrogen en-richment of the ponds during re�lling.

Sample ordination in relation to the �rst twoPCA axes produced a variation pattern for subs-tances dissolved in the ponds studied in north-western Spain as a result of intense evaporation,as well as indicating changes produced by desic-cation followed by pond re�lling.

In conclusion, this study has demonstratedthat salinity and concentrations of the majorions and nutrients in ponds in the northwest ofSpain are highly vulnerable to evaporation andtotal drought. Both processes resulted in a highconcentration of most of the ions, although in thecase of drought this was most pronounced whenthe ponds started to �ll slowly. However, evapo-

ration and drought had different effects on ioncomposition. An extreme reduction in water vo-lume resulted above all in an excess of chlorideand sodium, and a reduction in sulphate, whilstdrought of the ponds favoured oxidation of redu-ced sulphur compounds, with the consequent in-crease in sulphate during re�ll. Likewise, soil ru-noff from agricultural land as a result of autumnrainfall was a determining factor in the rise inpond water potassium levels. Hydrological regi-mes changes resulted in substantial modi�cationsto nutrient dynamics, probably involving variousmechanisms, such as the release of phosphorusfrom the sediment, and the formation of ammo-nium, both processes which would be facilitatedby a reduction in oxygen concentrations; the mi-neralisation of organic nitrogen and phosphorusassociated with pond desiccation; and the inputof nitrate from the surrounding land as a result ofsoil runoff caused by autumn rainfall.

In view of these results, it can be conclu-ded that hydrological variations caused by redu-ced rainfall could result in environmental pro-blems in terms of water body conservation. Inparticular, the increase in dissolved salts couldtransform some fresh water lakes into more orless salt water systems. Likewise, nutrient enri-chment could accelerate the process of eutrophi-cation in these water bodies. It should be bornein mind that these kinds of hydrological modi�-cations will occur more frequently in the future,both as the result of increases in various anthro-pogenic activities, particularly over-exploitationof aquifers and the development of new irriga-tion networks, and the result of possible climaticchanges, with severe droughts, which could giverise to frequent cycles of drought and rewettingin Mediterranean water bodies.

ACKNOWLEDGEMENTS

We would like to thank the members of the lim-nology group (University of Leon) for their assis-tance in laboratory and �eld work. This researchwas supported by the Junta de Castilla y Leon(LE27/98) and CICYT (Amb94-0292).


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Crustacean and rotifer seasonality in a Mediterranean temporary pondwith high biodiversity (Lavajo de Abajo de Sinarcas, Eastern Spain)

Mar�a Sahuquillo and Maria Rosa Miracle

Departament de Microbiologia i Ecologia, Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat deValencia, E-46100 Burjassot, Valencia, Spain.2

∗ Corresponding authors: [email protected]; [email protected]


ABSTRACT

Crustacean and rotifer seasonality in a Mediterranean temporary pond with high biodiversity (Lavajo de Abajo deSinarcas, Eastern Spain)

A follow-up study was made of planktonic and periphytic crustaceans and rotifers during two hydroperiods of consecutiveyears in a Mediterranean temporary pond. The pond is relatively large with quite long hydroperiods in wet years (6-8 months)and it has a very rich community (4 large branchiopods, 12 cladocerans, 9 copepods, 36 rotifers). Three phases in faunalcomposition, quite consistent from year to year, were distinguished: (1) Filling phase in autumn-winter is dominated by anos-tracans (endemic Branchipus cortesi, with low proportions of Branchipus schaefferi) and diaptomids, two univoltine species(Hemidiaptomus ingens inermis, Diaptomus cyaneus intermedius) and one multivoltine (Mixodiaptomus laciniatus atlantis).(2) Middle phase in spring dominated by cladocerans (Ceriodaphnia n.sp., Simocephalus vetulus, Ephemeroporus pinthoni-cus, Chydorus sphaericus, Alona azorica) in this phase is also abundant the conchostracan Maghrebestheria maroccana andthe notostracan Triops cancriformis. A shift toward insects occurs in the later part of this phase. (3) Desiccation phase in sum-mer with lower diversity (Moina micrura, Alona rectangula and cyclopoids). Rotifers showed a low contribution to biomassand were more important in the middle phase. These phases are also marked by an increase of nutrients and phytoplanktonchlorophyll in the �lling and desiccation phases and a decrease of these variables in the middle phase, resulting in phytoplank-ton clearance and greater water transparency, concurrent with macrophyte growth. Interannual variability was outstanding inshaping these phases. The year 2007 was preceded by a wetter autumn, whereas 2008 was preceded by a very dry autumnthus, in this second year the main hydroperiod was shorter and the �rst phase was merged with the middle phase. In thisshorter hydroperiod the open water microinvertebrate community reached lower biomass but attained a similar diversity sincerotifers became relatively more abundant and richer in species than in the 2007 main hydroperiod, when the community wasfully dominated by crustaceans.

Key words: Mediterranean temporary ponds, ecological succession, hydroperiod, large branchiopoda, Hemidiaptomus, cla-docerans, rotifers.

RESUMEN

Estacionalidad de los crustaceos y rot�feros en una laguna temporal mediterranea con alta biodiversidad (Lavajo de Abajode Sinarcas, Levante espanol

Se ha estudiado la estacionalidad de las comunidades de crustaceos y rot�feros planctonicos y perif�ticos en una charca tempo-ral mediterranea en varios hidroperiodos durante dos anos consecutivos. La charca tiene una extension relativamente grandecon un hidroperiodo largo en anos humedos (7-8 meses) y alberga una gran riqueza de especies (4 grandes branquiopodos,12 cladoceros, 9 copepodos, 36 rot�feros). Basandonos en los cambios en la composicion de esta fauna, se diferencian tresfases que se repiten de ano en ano, estas fases son: (1) Fase de llenado en otono-invierno, dominada por anostraceos (princi-palmente por el endemico Branchipus cortesi, con una baja proporcion de Branchipus schaefferi) y diaptomidos, dos especiesunivoltinas (Hemidiaptomus ingens inermis y Diaptomus cyaneus intermedius) y una multivoltina (Mixodiaptomus laciniatusatlantis). (2) Fase intermedia en primavera, dominada por cladoceros (Ceriodaphnia n.sp., Simocephalus vetulus, Ephe-meroporus pinthonicus, Chydorus sphaericus, Alona azorica), destacan tambien en esta fase la presencia del concostraceoMaghrebestheria maroccana y el notostraceo Triops cancriformis. Los rot�feros contribuyen poco a la biomasa y son algo

76 Sahuquillo & Miracle

mas importantes en esta fase intermedia. En la ultima parte de esta fase se produce un cambio hacia una mayor presencia deinsectos. (3) Fase de desecacion en verano que corresponde con una menor diversidad (Moina micrura, Alona rectangula yciclopidos). Las fases de llenado y desecacion se caracterizan tambien por un aumento de nutrientes y cloro�la �toplantonicamientras que en la fase intermedia su concentracion es menor, aumentando la transparencia del agua y el desarrollo de losmacro�tos. La variabilidad interanual determina la con�guracion de estas fases. El ano 2007 fue precedido por un otonohumedo mientras que 2008 fue precedido por un otono muy seco, por lo que en este segundo ano el hidroperiodo principal fuemuy corto fusionandose la primera fase con la intermedia y la biomasa de microinvertebrados en aguas abiertas fue muchomenor que en el hidroperiodo del 2007, sin embargo se alcanzaron valores similares de diversidad debido a una relativamentemayor abundancia y riqueza de especies de rot�feros con respecto al hidroperiodo del 2007, en el que dominaron plenamentelos crustaceos.

Palabras clave: Charcas temporales mediterraneas, hidroperiodo, sucesion ecologica, grandes branquiopodos, Hemidiapto-mus, cladoceros, rot�feros.

INTRODUCTION

Ponds have recently begun to receive increasingattention, one of the reasons being their exceptio-nal contribution to biodiversity. Collectively, theysupport considerably more species than otherfreshwater water body types and often constitutebiodiversity “hot spots” within a region or land-scape (Cereghino et al., 2008; Thiery, 1991). Inthe Mediterranean regions of Europe, temporaryponds have been identi�ed as a priority in the EUHabitats Directive. They are of interest as habi-tats for rare species and constitute last refugesof ancient species. However, due to their tem-porality they have been largely modi�ed, manyhave been drained, large peripheral parts of tho-se that do not attain their maximum level everyyear have been converted into agricultural �elds,others have been deepened to hold water perma-nently and nearly all are used and maintained forcattle watering. This implies that non-modi�edsystems are very scarce.

Among the inhabitants of the ponds, crusta-ceans and rotifers play an important role espe-cially at the �rst stages of colonization; manyrecent studies are based on extensive samplingcampaigns covering wide areas and environmen-tal gradients to study their distributions (Ebert &Balko, 1987; Ripley & Simovich, 2009; Alon-so, 1998). However, as Fahd et al.,(2007) poin-ted out, studies in intensive samplings over a sin-

gle or few ponds but covering different seasons(cumulative survey) are also required for accurateevaluations of zooplankton diversity and speciesrichness Although good examples of this type ofstudies can be found (Lake et al., 1989; Lahr etal.,1999; Taylor & Mahoney, 1990; Crosetti &Margaritora, 1987; Tavernini et al., 2005; Boixet al., 2004), they are less frequent.

The present study is framed in the second ap-proach and its speci�c objectives were to exami-ne the zooplankton community of a Mediterra-nean temporary pond, “Lavajo de Abajo” of Si-narcas (Valencia, Spain), along the hydroperiodand to examine some trends in the species com-position and seasonal changes of the zooplanktonpopulation in this habitat. This temporary pond isideal for this purpose because: (1) The hydrope-riod in Sinarcas pond is more or less predictableand in wet years is relatively long (6-8 months),although in dry years several discontinuous shor-ter hydroperiods are the rule. The pond is one ofthe largest in the Comunidad Valenciana (Miracleet al., 2008) and presents an important develop-ment of varied aquatic vegetation in spring. The-se characteristics have been pointed out by otherstudies as favourable conditions for high inverte-brate species richness; in particular, the length ofthe hydroperiod (Mahoney et al., 1990; Serrano& Fahd, 2005), as it implies more chances forspecies replacement in these �uctuating environ-ments. (2) This pond can be identi�ed as a refe-

Crustacean and rotifer seasonality in a Mediterranean temporary pond 77

rence site much closer than others to the pristinestate that can be expected in the temporary pondsof continental Mediterranean climate in open ba-sins. This temporary pond has attracted interestdue its particular and rich aquatic and amphibio-us �ora with Isoetes velata (Mansanet & Mateo1978) and has been included in the Nature 2000Network according to the EU ‘Habitat Directive’(Laguna et al., 2003). During a previous extensi-ve study of temporary ponds of the “ComunidadValenciana”, carried out in 2006-07 (Miracle etal., 2008), this pond stood out for its high largebranchiopod richness. Samples taken in this pondsince 1988 indicated the presence of a peculiarmicroinvertebrate fauna as well.

This work focuses on branchiopod, copepod,and rotifer temporal distribution in this tempo-rary pond, which, despite being greatly endan-gered, still conserves characteristic complex spe-cies associations during the hydroperiods of 2007and 2008. We will also highlight the high spe-cies richness observed since pond biodiversityhas been recognized as a signi�cant goal in pre-sent days, when so many habitats are threatenedby human activity or climate change.

METHODS

Study site

“Lavajo de Abajo de Sinarcas” is a temporarypond of the municipality of Sinarcas, located at869 m a.s.l. in the homonym basin, which is a na-tural depression made up of Plio-Quaternary sili-ciclastic deposits (ranas) lying on top of Mioce-nic sediments. “Lavajo” is one of the popular na-mes given to steppic, endorheic or semiendorheicponds, which are often connected to an aquifer tosome extent. The Sinarcas pond lies on a relati-vely independent surface aquifer (“rana aquifer”)easily replenished by precipitation. It occupiesthe centre of a �ooded meadow, now partly trans-formed into agricultural �elds (vineyards and ce-reals) and it is also used for sheep watering. Ithas a typical circular shape, which attained a ma-ximum surface area of almost one hectare and amaximum depth of 1.5 m during the study period.

The shores slope varies smoothly, providing a wi-de shallow peripheral zone that is at the mercy ofwater level �uctuations.

Sinarcas has a continental Mediterranean cli-mate, characterized by dry and hot summers,with the main rainfall occurring in autumn andspring and quite low winter temperatures withfrequent night frost. Mean annual rainfall (years1999-2008) was around 500 mm and monthlyevapotranspiration rates ranged from 26 mm inDecember to 181 mm in July (monthly means,years 1999-2008, IVIA Irrigation TechnologyService). The pond usually �lls up in autumnand typically dries up in late summer, but itcan have one or more dry spells in between,depending on annual rainfall.

Two kilometres from this temporary pond the-re is a second one, Lavajo de Arriba, which hasbeen arti�cially deepened to maintain water andhas become semi-permanent, becoming dry onlyin extremely arid years. The pro�le of the semi-permanent pond shows an abrupt slope that formsa hollow in one of its sides, with a maximumdepth of 2 m, which drains water from the sha-llower shores so the shallow peripheral zone re-mains �ooded only during short periods afterepisodes of heavy rain. Besides the general infor-mation as a priority habitat in Nature 2000 (La-guna et al., 2003), there are only references onits �ora (Mansanet & Mateo 1978; Mateo, 1983)and the �ndings of some interesting species in itsshore (Valentin et al., 2007; Fos et al., 2008).

Collection of samples

A follow-up study was made of planktonic andperiphytic crustaceans and rotifers in two con-secutives years: (1) during a long hydroperiod(December 2006-July 2007), (2) during a shor-ter hydroperiod (March-August 2008) and (3) inSeptember 2007 during a brief incidence of smallland grooves re�lling with rainwater in the dee-pest part of the pond basin. Furthermore, pre-vious samples taken in various years mainly inspring since 1988, were also analysed.

Samples were taken from different mesohabi-tats, in the open waters of the central area, andin zones with macrophytes. Integral water sam-


ples of the water column were taken, when pos-sible, with a transparent tube (5 cm internaldiameter, 1 or 0.5 m long, depending on ponddepth). Zooplankton was concentrated in situ by�ltering water samples through a 30 µm nytalmesh and �xed in 4% formalin. At least threetubes were taken at different points and integra-ted to get one composite sample. Two replica-te quantitative zooplankton samples were collec-ted every sampling date. In addition, zooplanktonwas collected in horizontal transects by towinga net of 45 µm. In the vegetated areas we ge-nerally took 3 qualitative samples by sweepinga 90 µm hand-net at different locations near theshore and at some distance from it. The pre-sence of large branchiopods (especially notostra-cans and conchostracans) was checked in veryshallow shore areas by carrying out an exhaus-tive visual examination. All the material collec-ted was �xed in 4% formaldehyde. For quanti-tative samples all specimens were identi�ed andcounted and results were expressed as individualsper litre. Length was also measured for each spe-cies and crustacean biomasses were calculatedfrom published regression equations (length-dryweight, Bottrell et al., 1976, Dumont et al., 1975or length-carbon regressions: Vasama & Kankaa-la, 1990; Luokkanen, 1995. Rotifer carbon con-tents were obtained from Latja & Salonen (1978)and Telesh, Rahkola & Viljanen (1998). Dryweight of zooplankton was calculated assumingthat the carbon content is 40% of dry weight.For net samples we counted sub-samples to ob-tain relative abundances, until no statistical va-riation was observed or no other new specieswere found. Additionally, the remaining materialwas examined at lower magni�cation to trace lessabundant large-sized taxa.

Water samples were also taken in the openwater for biological and chemical analyses andsome limnological variables were determined insitu (temperature, oxygen, conductivity, pH, maxi-mum depth, vegetation cover, etc.). Turbidity, al-kalinity, chlorophyll-a, total phosphorous and totalnitrogenwere determined followingAPHA (1992).

Daily rainfall and temperature data (Fig. 1),provided by Sinarcas Meteorological Station, weresmoothed using a moving average of 10 days.

Data analysis

For each sampling date the Shannon diversity in-dex H′ (mean and variance) for cladocerans +copepods was estimated by the jackkni�ng ap-proach (Zahl, 1977) taking into account all thesamples collected. Bray-Curtis dissimilarity in-dex was used to compare cladocerans + copepodsfrom open water versus among plants + shore,using the square root transformation of the ave-rage proportion of these crustaceans in each ha-bitat for each sampling date. The index of �uc-tuations formulated by Dubois (1973) as Taylor’sexpansion of Shannon diversity index around areference state D0 =

∑pi log2 ( pi/Pi), ( pi = pro-

portions of species i and Pi = mean of pi) wasalso calculated as a measure of stability (Mira-cle, 1978), using rotifer + crustacean proportionsfrom quantitative and 45 µm net samples. K in-dex was calculated according to Margalef (1997)as K = log S/ logN (S = species number, N =total density or total biomass from quantitativesamples).

RESULTS

Environmental characteristics

In general, limnological features responded towater-level �uctuations determined by rainfall,although the variation in pond level is subject toinertia, because it is regulated by the perched, su-per�cial “rana” aquifer. The duration of hydro-periods differed in the studied years (Fig. 1). Inthe �rst year, a long hydroperiod involving rain-fall in autumn and spring was observed; in thesecond year the pond was dry in late autumn-early winter. After �lling to a moderate level inautumn 2006, the pond was maintained throughwinter-early spring 2007 until the important pre-cipitations of April increased its water volume,attaining a level that surpassed the average yearlylimits, thus �ooding the agricultural �elds adja-cent to the pond basin. High evapotranspirationvalues in summer and very low rainfall after la-te spring prevented the hydroperiod from lastingbeyond early July. Rainfall in September �lled afew very small puddles in the deepest part of the


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200820072006

Figure 1. Rainfall and air temperature in the village of Sinarcas (grey areas; smoothed daily data 2006-08). Limnological featuresin Lavajo de Abajo de Sinarcas during two hydroperiods in 2006-07 and 2008: maximum depth (Z max), and water temperature(black circle and solid line) conductivity and alkalinity dissolved oxygen and pH, turbidity and planktonic chlorophyll-a and totalphosphorous and total nitrogen. Precipitacion y temperatura en el pueblo de Sinarcas (areas grises; datos diarios suavizados 2006-08).Caracter�sticas limnologicas en el Lavajo de Abajo de Sinarcas durante los hidroperiodos de 2006-07 y 2008: profundidadmaxima (Z max), y temperatura del agua (c�rculo negro y l�nea solida) conductividad y alcalinidad, ox�geno disuelto y pH , turbidezy cloro�la-a planctonica y fosforo total y nitrogeno total.


basin with no more than 10 cm of water. Autum-nal precipitation was very low in 2007 and, aftera shallow water cover of short duration, the pondbecame dry in late autumn-early winter, but re�l-led in February 2008. Again, abundant precipi-tation in May increased the water level, �oodingthe adjacent agricultural �elds and the hydrope-riod lasted until the end of August.

The maximum depth and area clearly corres-ponded with spring rainfall peaks, (April 2007and May 2008, Fig. 1). Water temperature onthe sampling dates varied from +5 ◦C in winterto +28 ◦C in summer. Conductivity has increa-sed in recent times since the use of salt for de-icing the nearby road, peaking in the winters withsnow, as in 2008, when it reached 1106 µS cm−1,whereas conductivity measured in May 1988 was80 µS cm−1. In �gure 1, it can be observed thatconductivity was lower during winter 2007 with-out snow and remained lower during that year.In both hydroperiods, severe evaporation in sum-mer increased conductivity before desiccation,but never reached the winter values, when saltwas used in the road. Alkalinity is high for thetype of geological substrate but it probably hasincreased due to agricultural practices, since it ismuch higher than in the nearby arti�cially dee-pened permanent pond. Turbidity was higher inwinter after �lling and also in periods of less wa-ter. Water chlorophyll-a, turbidity and TP dimi-nished in spring due to the important �ltering ofzooplankton biomass and nutrient intake by ma-crophyte development, a clear water phase in thisperiod was very apparent. Later, these variablesincreased sharply at the end of the �rst hydro-period studied, but not so clearly in the secondperiod. Oxygen levels measured around middayvaried between 68% and 138% saturation resul-ting in a corresponding variation in pH of 7 to 9,with maxima at the beginning and the end of thehydroperiods, when primary production is high-er. Oxygen undersaturation was observed just af-ter spring rains (April 07, May 08) that may beattributed to replenishment of the pond in partthrough groundwater �ow, mixing the water co-lumn with the poorly oxygenated bottom waters.

A visual follow up was made of the aquaticvegetation development on the different sampling

dates. In late winter only young stems of Juncusand Eleocharis developed in the water, most ofthe pond consisting of open waters with a mo-re or less heavy development of �lamentous me-taphyton depending on the years, in part due tofertilization (mainly nitrogenous) of the adjacentagricultural �elds in late winter. The metaphytonwas especially dense at the beginning of the 2008hydroperiod (March), the year with low rainfallin autumn-winter; it covered the whole pond as a�lamentous mat and slimy masses of these greenalgae accumulated on the shore and plant stems.The aquatic vegetation began to grow conspi-cuously at the beginning of spring, to form twodifferent rings - when well developed: a Ranun-culus dominated shallower outermost ring and aMyriophyllum dominated ring in the deeper morecentral part. At the end of the hydroperiod almostno open water could be seen. Anuran larvae werecommonly present and larvae of the newt Pleuro-deles waltl were observed in spring.

Crustacean and rotifer succession

A total of 12 cladocerans, 9 copepods (3 cala-noids, 5 cyclopoids, and 1 harpacticoid), 1 con-costracan, 1 notostracan, 2 anostracans and 36 ro-tiferans were collected and identi�ed in the activecommunity. The majority of these species arestrictly linked to temporary waters.

Population dynamics of main species during thetwo hydroperiods of consecutive years are shownin figure 2 (from plankton quantitative samples)and �gure 3 (from net samples among macrophy-tes). Three main phases can be distinguished:

(1) Calanoid phase in late autumn-winter

Best observed in the longer hydroperiod of 2006-07. The pond �lled by autumn-winter rainfall,had shallow waters with very sparse vegetation.A planktonic community of large-sized orga-nisms dominated (characterized by the coexisten-ce of anostraca and three diaptomids of differentsizes). The endemic Branchipus cortesi was themain anostraca species, but Branchipus schaef-feri could coexist at low numbers. Both speciesshowed a percentage of individuals with the ab-


normal rostrum/antenna morphotype, that someauthors consider typical of Branchipus visnayi;however, it seems to be just a morphology thatsome specimens undertake as a response to �xa-tives (Beladjal & Mertens, 1999; Miracle et al.,2008). At the very beginning of the hydroperiod

in autumn, when water is still warm, Triops can-criformis can also be found in the littoral perip-heral zone. The most characteristic diaptomidsare two univoltine speciesHemidiaptomus ingensinermis, Kiefer (4 mm), recorded for the �rst ti-me in the Iberian Peninsula, and Diaptomus cya-

Figure 2. Population dynamics of main crustacean and rotifer species in Lavajo de Abajo of Sinarcas from quantitative planktonsamples taken during the two main wet phases. Densities in ind L–1 are the averages of two sampling points. Dinamica de laspoblaciones de las principales especies de crustaceos y rot�feros en el Lavajo de Abajo de Sinarcas en las muestras cuantitativas deplancton tomadas durante las dos fases humedas principales. La densidad en ind L–1 corresponde al promedio de los resultados dedos puntos de muestreo.


neus intermedius, Aguesse & Dussart (2 mm).They are the earliest colonizers, initial samplescollected more or less two months after �rst �-lling (a shorter time in the second year) weremade up of adults with absence of nauplia andcopepodites, this denotes that egg hatching fo-llows a desiccation period and happens more orless at once and also that resting eggs are con-centrated in the deepest central zone of the pond.The third diaptomid speciesMixodiaptomus laci-niatus atlantis (1.2 mm) hatched a little later andhad more than one annual generation. Early inthis phase a benthic harpacticoid Canthocamptusstaphilinus was very abundant, probably peakingbefore calanoids development. Cyclopoids Me-tacyclops minutus and Cyclops abyssorum divul-suswere present since early �lling. Rotifers had avery low contribution to biomass, Keratella qua-drata was the main planktonic species, but evenin the plankton samples periphytic species werealso found, the most abundant ones were Euchla-nis dilatata at the beginning and Lepadella trip-tera at the end of the period.

The duration of this phase in this pond, mar-ked mainly by the occurrence of H. ingens iner-mis, is approximately from December to March,and corresponds with maximum air temperaturesbelow +15 ◦C. In the quantitative samples, co-llected diaptomids contributed up to 79 and 90%(February 2007 and March 2008 respectively) ofthe zooplankton biomass, and H. ingens inermisalone contributed up to 38%.

(2) Cladoceran phase in spring

Water changes from turbid to transparent andconsumers predominate in the water. The pondhad a well developed macrophyte cover and tad-poles and insect larvae were abundant. Benthic,littoral and/or phytophyllic taxa dwelled togetherwith planktonic taxa. In the planktonic commu-nity Ceriodaphnia n. sp. and anostraca (Branchi-pus species) dominated. Ceriodaphnia n. sp. pre-sented a succession of two morphs, a spinulosaform, characterized by very heavy reticulationsthat from a lateral view look like small spines,appeared earlier. But its dominance was soon re-placed by a smaller form of this Ceriodaphnia

with smooth reticulations. This Ceriodaphnia issimilar to C. quadrangula as described by Alon-so (1996), but according to this author and toD. Berner (personal communication) it rather co-rresponds to a new species which are now descri-bing, the main difference being that the new spe-cies has a cervical fenestra, which is not foundin C. quadrangula s.s. Planktonic cladoceranscoexisted with a rich association of periphyticcladocerans, composed of at least �ve differentspecies of good swimmer chydorids (i.e. Ephe-meroporus, Chydorus) and Simocephalus vetu-lus, also Alona azorica had a maximum in thisperiod. Amphigonic reproduction, also registeredin �gure 3 indicated clearly the species replace-ments, with the �rst to come being the plankto-nic Ceriodaphnia species, followed by periphy-tic cladocerans (Simocephalus, Dunhevedia andEphemeroporus) and later by the more benthicAlona azorica. In the littoral benthos two largebranchiopods were found Maghrebestheria ma-roccana and T. cancriformis. Metacyclops minu-tus was the most abundant copepod. Univolti-ne calanoids had completely disappeared, but themultivoltineM. laciniatus atlantis was still abun-dant. Dominant planktonic rotifers differ fromyear to year and a variety of periphytic rotifersbegan to develop (including uncommon preda-ceous species such as Cupelopagis vorax and As-plachnopus multiceps).

In Lavajo de Sinarcas this phase is observedsince early spring (end of March) until mid June,more or less, and corresponds with maximum airtemperatures below +25 ◦C. Although the phaseduration is shorter than the �rst phase, the num-ber of species is higher.

(3) Desiccation phase

As the hot summer is approaching, the level ofthe pond diminishes, but the length of this pha-se depends on the intensity and timing of springrainfall. Large branchiopods had disappeared be-fore the start of this phase. In these warm wa-ters, planktonic crustaceans are characterized bythe almost absolute dominance of Moina micru-ra with a small proportion of cyclopoids, mainlythe predator C. abyssorum divulsus but M. minu-


Mixodiaptomus laciniatus

Branchipus cortesiBranchipus schaefferi

Metacyclops minutusMacrothrix hirsuticornis

Hemidiaptomus ingensDiaptomus cyaneus

Canthocamptus staphilinus

Euchlanis dilatata

Cyclops abyssorum

Lepadella tripteraKeratella quadrata

Brachionus quadridentatus

Ceriodaphnia (spinulosa form)

Ceriodaphnia n.sp.

Lepadella patellaTrichocerca spp.

Chydorus sphaericusDunhevedia crassa

Ephemeroporus phintonicus

Simocephalus vetulus

Polyarthra sp.

Tropocyclops prasinus

Leydigia acanthocercoidesMoina micrura

Alona rectangula

Leberis diaphana

Lecane luna

Alona azorica

Triops cancriformisMaghrebestheria maroccana

Filinia longiseta

Eucyclops serrulatusDaphnia pulex

Testudinella patina

2006-07

Dc Fb Ap My Jn Sp

2008Semi permanent pondMr My Jn Ag

1

2

3

Hexarthra spp.

Lecane grandis

Cupelopagis vorax

Asplachnopus multiceps

Notommata copeus

Jl

Anuraeopsis fissa

Figure 3. Summary of seasonal succession of crustaceans and rotiferans found in Lavajo de Abajo of Sinarcas from sweep netsamples among macrophytes during two hydroperiods, 2006-07 and 2008. Circles indicate the relative abundance of each speciesin each sampling day with respect to the total number of individuals of this species over each wet phase. White circles indicate thepresence of ephippial females. Number on the left side refers to seasonal groups of species (1 to 3, see text). On the right side, greycircles indicate species presence in a nearby simultaneously sampled pond, Lavajo de Arriba of Sinarcas (arti�cially converted in asemi-permanent pond). Sucesion estacional de crustaceos y rot�feros en el Lavajo de Abajo de Sinarcas en muestras con red de manoentre macro�tos durante dos hidroperiodos, 2006-07 y 2008. Los c�rculos indican la abundancia relativa de cada especie en cadad�a de muestreo respecto del total de individuos de esta especie en cada fase humeda. Los c�rculos blancos indican la presencia dehembras e�piales. A la izquierda se senala con un numero los correspondientes grupo estacionales de especies (1 a 3, ver texto). Ala derecha, en c�rculos grises, se senala la presencia de las especies en muestras tomadas simultaneamente en una charca cercana,Lavajo de arriba de Sinarcas (arti�cialmente transformada en semi-permanente).


tus was also present. In the year with a longerhydroperiod some adults of M. laciniatus atlan-tis still remained. Depending on the year, roti-fers may be more or less abundant, mainly com-prising the more detritivorous Hexarthra miraand Trichocerca spp. Phytophylous cladoceranswere now less abundant being replaced by ben-thic ones, such as Alona rectangula and Leydigiaacanthocercoides. In this case also the planktonicspecies M. micrura showed an earlier amphigo-nic reproduction than A. rectangula.

In the second studied period (2008) later rain-fall in spring prolonged the hydroperiod until Au-gust. In this month the pond was practically cove-red by the structural parts of vegetation stands indifferent rings, leaving only a small central aper-ture. Invertebrate predators were mainly Chaobo-rus in the central open water and heteropteransin the shores. Diversity drastically diminished,but density was high in the small water volume.The benthic cladoceran A. rectangula dominatedaltogether with periphytic rotifers. Phytophylouscladocerans were very scarce. The occurrence ofLeberis diaphana (0.6 mm) was remarkable; itwas recorded for �rst time during that exceptio-nal summer, as was the presence of several preda-tory rotifers, such as Notommata and Asplachno-pus multiceps (an individual of the latter had fourChydorus sphaericus inside). However, at the sa-me time, plankton was dominated by opportu-nistic species, newcomers that are not characte-ristic of temporary ponds, such as the cyclopoidTropocyclops prasinus.

In the two study years the pond differed in wa-ter level, extension and hydroperiod length. In the�rst more humid year the pond had a high level ofwater from autumn until early summer, whereasin the second year the pond was dry in late au-tumn – early winter and it was �lled in late win-ter, but then due to late spring rains the hydrope-riod lasted until midsummer. In this second year,winter species were much less abundant and hadto cope with the prompt development of springspecies; calanoids and anostracans were muchless abundant and much less persistent, eventhe more numerous and enduring M. laciniatusatlantis was scarce and �nished its active cy-cle long before. Furthermore, during the second

year, rotifers presented a higher relative abun-dance and a higher number of periphytic spe-cies (mainly Lecanidae) than in the previous year.

As a comparison, �gure 3 indicates the spe-cies found in the nearby, simultaneously sam-pled, “Lavajo de Arriba de Sinarcas”, convertedinto a semipermanent pond by man digging (pre-sence of species in any of the sampling dates).This pond did not dry during the study period andspecies richness was less than half that found inthe temporary pond, 11 crustacean species werefound, all of them widely distributed.

Dynamics of diversity

Diversity index and species richness showed mar-ked seasonal and inter-annual variations accor-ding to the above-mentioned changes in commu-nity composition (Fig. 4). The pronounced slopeof accumulated species richness indicates highcommunity change. The number of species wasmore or less equal in both years but the secondyear was richer in rotifer species. Shannon diver-sity index, H′ applied to crustacean proportionsdiffered seasonally (ANOVA p < 0.01, appliedto 2007 and 2008 samples separately). The mi-nimum H′ values were found in the samples co-rresponding to changing conditions: (1) just after�ooding and (2) at the beginning of desiccation.H′ increased with time after the pond was reple-nished and reached maximum values in spring,with a more stable environment of high waterlevel, warm temperatures and high developmentof aquatic plants, providing refuge and feedingresources. Then, it decreased in summer whenhot temperatures and dryness reduced water le-vel. From the multiple samples taken each day,the overall values of the diversity indices werecalculated by the jackkni�ng procedure to ob-tain less biased estimates with a con�dence in-terval (Fig. 4). The general trend of this estima-tor through time was the same as that previouslydescribed for single samples, with a maximumin spring. The jackknife estimator compensatesthe underestimation associated with sampling si-ze but also re�ects habitat heterogeneity, as thedifference between mean sample diversity andjackknife estimator. There is a correspondence


Figure 4. Dynamics of different parameters during the two hydroperiods studied in Lavajo de Abajo of Sinarcas: Crustacean(cladoceran + copepods) sample diversity (Boxplot boundaries indicate the 25 and the 75th percentiles, a line within the box marksthe median), and Jackkni�ng estimator of crustacean diversity with its standard deviation. Species richness of crustaceans + rotiferscalculated over all the samples collected every sampling date. Cumulative species richness of crustaceans + rotifers and Bray Curtiscrustacean dissimilarity between habitats: open water and amongmacrophytes. Dubois �uctuation index calculated around a referencestate (see methods) for crustaceans + rotifers. Ratio of crustaceans + rotifers biomass/chlorophyll-a and diversity (H′, for biomassof crustaceans + rotifers). Total crustaceans + rotifers biomass, mean (�lled circles) and relative contribution of different groups tototal biomass (stacked bars). Dinamica de diferentes parametros durante los dos hidroperiodos estudiados en el Lavajo de Abajo deSinarcas: Diversidad de las muestras de crustaceos (cladoceros + copepodos, los l�mites de las cajas indican los percentiles 25 y75, la l�nea dentro de la caja senala la mediana), y estimador “Jackkni�ng” de la diversidad con su desviacion estandar. Riqueza deespecies de crustaceos y rot�feros calculado sobre todas las muestras recogidas durante cada fecha de muestreo. Riqueza acumuladade especies de crustaceos + rot�feros e �ndice de disimilaridad de Bray Curtis entre los crustaceos en aguas abiertas y en macro�tos.Indice de �uctuacion de Dubois calculado en torno a un estado de referencia (ver metodos) para los rot�feros + crustaceos. Relacionentre la biomasa de rot�feros + crustaceos y la cloro�la-a, y diversidad de la biomasa de rot�feros + crustaceos (H′). Biomasa totalde rot�feros+ crustaceos: valor medio (c�rculos negros) y contribucion relativa de los diferentes grupos (barras acumuladas).


between these differences and habitat heteroge-neity, estimated as the Bray-Curtis dissimilaritycoef�cient between samples from the open wa-ters and from the littoral + among plants. Dissi-milarity was important in winter when the pondhad scarce aquatic vegetation; however, windpromotes not only the mixing of waters but al-so a non-homogenous distribution of planktonicorganisms, giving rise to a coarse-grain distribu-tion, which was re�ected in our samples. Springrainfall homogenized and a low dissimilarity wasobserved just after the rains (April 2007 and May2008). With time, plant development stabilizedthe water column and promoted a �ne-grain habi-tat diversi�cation and the community recoveredhabitat heterogeneity, so dissimilarity increased(as in June 2007). Later summer desiccation pro-ved a powerful de-structuring force that reduceddiversity and heterogeneity (as in August 2008).

The Dubois �uctuation index indicates thestability of the community. Higher values indica-te the periods when the community is far fromthe reference state de�ned as the average spe-cies proportion over the whole study period. Inour samples the periods with strongest devia-tions were associated with initial �ooding andespecially with the end of the hydroperiods co-rresponding to extreme conditions due to desic-cation (high temperatures, intensive predation,and reduced water volume).

Density of microcrustaceans and rotifers didnot differ greatly between the two years, but ma-ximum biomass achieved was much greater the�rst year. The main reason was the higher relativecontribution of calanoids during the �rst year andthe higher contribution of rotifers during the se-cond year (Fig. 4), although rotifers were alwaysmuch less important than crustaceans. It is clearthat the system in the longer hydroperiod can at-tain a higher biomass with larger organisms. Theshorter period favours a community of smaller-sized organisms than can develop further, but thearrival and growth of opportunistic species is alsoeasier when changes occur. The ratio zooplank-ton/chlorophyll is higher in the �rst phase andthen diminishes just after re-�lling events beforeincreasing afterwards. It should vary with diver-sity but in the shorter 2008 hydroperiod due to

merging of the �rst and second phases, diversitywas anomalously higher in May after �ooding.

The community dynamics change (Fig. 5), ex-pressed as the relationship between density orbiomass and the number of species, which wasproposed by Margalef (1997), is a good approachto compare these year cycles. After winter �oo-ding there is a large increase in the density or bio-mass with low diversity, then productivity decli-nes and diversity increases. Later an increase inlight and temperature, as well as rainfall, may en-

Figure 5. Idealized trajectory of the community structure du-ring the two wet cycles 2007 (solid points and line) and 2008(dashed line and empty points). Points are the monthly meansof rotifer+crustacean species number in relation to their den-sities or biomass during the two wet cycles. K = log speciesnumber/log density K′ = log species number/log biomass. Tra-yectoria idealizada de la estructura de la comunidad duran-te los dos ciclos humedos estudiados, 2007 (l�nea continua ypuntos solidos) y 2008 (l�nea discontinua y puntos vac�os). Lospuntos representan la media mensual del numero de especies decrustaceos y rot�feros en realcion con su densidad o biomasa enlos dos ciclos humedos.K = log no de especies/log densidad,K′= log no de especies/log biomasa.


hance productivity with a new increase in densityor biomass and diversity drops slightly, but imme-diately increases again due to the rich sedimentseed bank. Then, the desiccation process decreasesdiversity and the biomass of characteristic species,but can increase opportunistic species biomass.

DISCUSSION

General pattern of community succession withthree phases

In Lavajo de Abajo de Sinarcas, two characte-ristics could be identi�ed; �rstly the singularityof its aquatic fauna and secondly, the clear suc-cessional phases made up by the replacement ofdifferent taxonomic communities. Although a ge-neral seasonal pattern of species associations canbe observed, there are some variations dependingon the timing of rainfall and the duration of thehydroperiod. Lavajo de Abajo may vary from se-veral discontinuous pond events of a few monthsto a continuous �ooding period that can even co-ver part of the summer season. The �rst hydrope-riod studied had an adequate duration (8 months)and timing of occurrence (from autumn 2006 tosummer 2007) for a clear observation of the de-velopment of the successional phases.

The �rst water �lling involves an input ofenergy to the system; the dissolution of nutrientsinduces the growth of planktonic primary pro-ducers and subsequently of planktonic �lter fee-ders, which present a clear variation in body sizesthat allows the consumption of food of a wi-de range of particles avoiding competition. Thetemporary ponds of the Mediterranean basin �l-led typically after autumnal rainfall (in July inthe southern hemisphere), corresponding with thecoolest months of the year and short photoperiod.In “Lavajo de Abajo de Sinarcas” this earlier pha-se at the end of autumn-winter is the most pecu-liar and it is characterized by anostraca and threecalanoid species (two of them are large univol-tine species with long life spans) representing avery specialized community well adapted to thisperiod and exclusive from it, that takes advan-tage of the initial planktonic conditions. Com-

parative studies on temporary ponds from loca-lities with large differences in climate and zoo-geography have shown that considerable simi-larity is evident amongst the seasonal cycle ofinvertebrates (Williams, 1997). An initial coloni-zation after �ooding by co-occurring calanoids ofdifferent sizes has also been described in manylocations where annual cycles have been follo-wed (i.g. Champeau, 1971, in Europe; Lake etal., 1989, in Australia with 4 co-occurring spe-cies of calanoids; Taylor & Mahoney, 1990, inSouth Carolina ,USA). Moreover, in these cases,as in Lavajo de Abajo of Sinarcas, this phase isalso followed by a spring community dominatedby cladocerans. This cladoceran phase was calledthe middle phase by Lake et al. (1989). Taylor &Mahoney (1990) hypothesized that later emergenceof cladocerans is related to food resources andtemperature conditions. Food is low when pondsfill in winter and newly hatched cladocerans mustbegin to feed immediately (Goulden & Henry,1984), differing from newly hatched copepods andanostraca larva that could relay on egg reserves.

In this middle phase, another input of energy,now from spring rainfall, give rises again to ahigher biomass and then succession progressi-vely advances. A “clear water phase”, as descri-bed in permanent lakes (Sommer et al., 1986) ap-pears as a consequence of zooplankton increasebut, in this shallow pond also due to the expectedreduction of turbidity by macrophytes. The zoo-plankton community is dominated by cladoce-rans, although many of them are species associa-ted with plants. The middle phase length may beshorter than the �rst phase but the number of spe-cies is higher and diversity reaches its maximum.Main attributes of succession may be followed inthis middle phase, such as a decline of the ratioproduction/biomass, an increase of the ratio zoo-plankton/chlorophyll and an increase of diversity,although they �uctuate with perturbations due tore-�lling events after heavy spring precipitations.Succession proceeds with a switch to dominan-ce of larger and more complex organisms, ma-crophytes and insects and diversity of crustaceansand rotifers may diminish. This complex auto-organization and high biotic interactions has ledto de�ne this phase as an autogenic phase by so-


me authors (Lake et al., 1989; Boix et al., 2004)to indicate that, in great part, it is the result ofautogenic biological processes in the pond to dif-ferentiate from the �ooding and desiccation pha-ses that are considered to have a high in�uenceof allochtonous factors.

The desiccation phase occurs in summer andis characterized by a strong reduction of spe-cies richness and the occurrence of more ubiqui-tous species at the end of this phase. As in otherplaces (Crosetti & Margaritora, 1987), the mainplanktonic species is Moina micrura that appea-red when other cladocerans diminished. Com-munity changes are abrupt; the stressful condi-tions during the drying process decrease speciesrichness, however subsequent die-back of aqua-tic plants and emergence of aerial insects, as wellas con�nement and reduced volume of water willproduce again a rise in density or biomass of mi-crocrustaceans and rotifers. But the directiona-lity of density or biomass of microinvertebratescould be variable depending on the presence ofnumerous young stages of species in rapid deve-lopment or many individuals of small species asrotiferans. As in other studies, there is an increa-se of invertebrate predators (Lake et al., 1989) inthe centre of this phase. If this phase is prolongedsome ubiquitous species such as the cyclopoid T.prasinus can colonize the pond. In “Lavajo deAbajo” we attribute the presence of T. prasinusin August to dispersion by sheep or other meansfrom the nearby arti�cially permanent pond.

Interannual variability

In this �uctuating environment, the seasonal cy-cle of the active community may show a highinterannual variability of its structure, althoughmain elements are present. According to Mar-galef (1997) the relationship between number ofspecies and number of individuals (or biomass) isa good approach to look for structural or diversitychanges in the community. In �gure 5, idealizedtrajectories of the structure of crustacean-rotifercommunity in the seasonal cycle, based on avai-lable monthly averages, seemed to indicate thatthe cycle begins with a relatively high richness ofspecies and that in both years a similar maximum

value of species richness was attained in May.However in the wetter year, with a long lastinghydroperiod beginning in autumn, crustacean do-minance was the rule and a higher biomass wasreached during colonizing and desiccation phasesthan in the dryer year and a higher biomass wasmaintained as well during the middle phase. Onthe other hand, in the later stages of this wetteryear, densities were much lower to those of thedryer year, indicating that biomass consisted oflarger animals with lower rates of growth. Whe-reas in the dryer year, with shorter interrupted hy-droperiod, the main one beginning in March, ro-tifers were more diverse and more abundant thanin the wetter year, although crustaceans contribu-ted also to biomass in greater proportion (Fig. 4).In the dryer year, the �rst phase was the most af-fected, giving rise to a phase at the end of wintercharacterized by the fusion of the two �rst pha-ses, microcrustaceans of the two phases autumn-winter and spring had to coexist, in detriment ofthe early colonizers. In this dryer year the leastfrequent species among calanoids as well as therarer cladoceran species or forms were less abun-dant or not found.Moreover, in this dryer year, thelower development of copepods and anostracans fa-voured rotifers that increased the number of speciesper sample, but also influenced the accumulatednumber of species due to the higher seasonalityof this short lived group of organisms (Fig. 4).

Phenology and sediment bank

Production of resting stages and the timing ofhatching from them determines the dynamicsof the active populations (Champeau, 1971, Cros-seti & Margaritora, 1987), subsequently mecha-nisms such as food limitation and predation in-�uence also the densities of the different species.

The phenology of faunal elements is the maincue determining the seasonal phases, diapauseand hatching adaptations regulated by tempera-ture and photoperiod, among other factors, inbranchiopods and copepods are the main deter-minants of replacement patterns. Crosetti andMargaritora (1987) pointed out that despite dif-ferences in duration of hydroperiods, cladoce-rans followed similar cycles, indicating the ma-


jor role of temperature and photoperiod in the li-fe cycle. The same is true in “Lavajo de Abajo”where cladocerans showed successive amphigo-nic reproductions according to their appearance.Champeau (1971) also described how diapauseeggs of winter diaptomids need a dry summerperiod with high temperatures and then the au-tumnal cooling for hatching. In summary, diffe-rent changing conditions trigger egg hatchingsof branchiopods and calanoids or activate dia-pausing stages of cyclopoids or harpacticoids,and their populations develop in pulses followingthe environmental cue.

When a succession begins in the new wet ha-bitat after drying, fast growing and opportunisticspecies would be expected to develop earlier, butin this temporary pond the strategies adapted bythe earlier community after �rst �ooding whenit occurs in winter, is dominated by low growthand large species, especially calanoids adaptedto interannual persistence, in detriment of highgrowth in a particular year, probably bet-hedgersstrategist to maximize geometric mean �tness(DeWitt & Lagerhans 2004). This suggests thata larger temporal scale is important; apart froma habitat that begins at each hydroperiod and canbe analysed in a short time scale, there is a pre-dictable cycle shaped by a stable community thatbecomes seasonally activated.

Singular and rich community of an ancienttemporary pond

From a regional point of view many of the spe-cies found in Lavajo de Sinarcas have an ex-clusive occurrence in this pond. Within the spe-cies recorded we have found one Iberian endemicanostracan, Branchipus cortesi, and the conchos-tracanMaghrebestheria maroccana, both speciesare very rare and formerly believed to be restric-ted to the western part of the Iberian Peninsu-la (Alonso & Jaume, 1991; Perez-Bote, 2004).Their presence in Lavajo de Abajo of Sinarcasindicates that the distribution of these species iswider, since Sinarcas is in the Eastern border ofthe Peninsula high plateau, and that it may bemore related to a relatively well preserved si-milar habitat than a too strict geographical po-

sition. Other species have been recorded for the�rst time in the Iberian Peninsula such as H. in-gens inermis, L. diaphana and a spinulated formof Ceriodaphnia n. sp. There are also uncom-mon species such as Ephemeroporus phintonicusand Alona azorica. In Lavajo of Sinarcas a com-bination of circum-Mediterranean fauna, steppicNorth-African species and species from southernEuropean mountains co-occur. The multispeciesoccurrence of large branchiopods and calanoidsin this pond is remarkable, since single occurren-ces within these groups of organisms is the mostcommon situation. However, the association ofcalanoid species of different sizes in the Medite-rranean basin has been noted by different authorsin well structured ponds (Gauthier, 1928, Cham-peau, 1971, Miracle, 1982, Alonso, 1987, Marro-ne & Naselli-Flores, 2004). The endemic charac-ter and uncommonness of several of the speciessuggests that this is a well established commu-nity of biogeographical and historical interest. Infact, this fauna still persists in this typical “rana”pond whose relatively soft waters have been re-cently altered, increasing its alkalinity and chlo-ride contents due to expanding agricultural activi-ties and road de-icing practices, respectively. Theoutermost part of peripheral zones of this tempo-rary pond have been converted into a cereal �eldand a vineyard, that are �ooded every spring, thisis highly risky for the rare large littoral/benthicbranchiopods whose resting eggs were observedin the peripheral zones, such as M. maroccanaand T. cancriformis (Miracle et al., 2008).

This dynamic point of view about commu-nity richness in temporary ponds implies that themaintaining of its natural cycles is a main tar-get for conservation. The natural succession is in-ternally fed by the rich dormant community sto-red in the egg bank (Brendonck & De Meester,2003) and then the well structured communitymaintains some inertia to new opportunistic co-lonizers. On the other hand, the manipulation ofthe physical characteristics of the pond results inan increase of opportunistic species as it occursin the excavated nearby semi-permanent pond. Insummary, conversion of peripheral �ooding landsin agricultural �elds, fertilization and pesticidetreatments in this and adjacent �elds, use of salt


on the road and pond improvement schemes forwater permanence are seen as alarming threadstowards the survival of “Lavajo de Abajo de Si-narcas”. Accordingly, this pond should be identi-�ed as a priceless site for conservation of a bio-diversity hot spot and an ancient natural type oftemporary pond ecosystem. All land that is sus-ceptible to �ooding in the pond basin should notbe considered as wasteland nor as land that needsrestoration, instead it should be conserved andprotected from the above mentioned threats byremoving human activities from it, even if doesnot �ll in several years. Furthermore it is also ne-cessary to regulate those activities that could havean impact upon its watershed.

ACKNOWLEDGEMENTS

We are very grateful to Eduardo Vicente for hishelp in the �eld and laboratory work, and alsoto Sara Morata and Antonio Picazo for the helpin chemical analyses. We thank also I. Lacom-ba and V. Sancho for assistance in the �eld andCoop.V.V. ‘La Protectora’ in Sinarcas for meteo-rological data. This research has been supportedby the EC project LIFE05/NAT/E/000060.

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The pond biodiversity index “IBEM”: a new tool for the rapidassessment of biodiversity in ponds from Switzerland.Part 1. Index development

Sandrine Angelibert, Veronique Rosset, Nicola Indermuehle & Beat Oertli∗

hepia Geneva, University of Applied Sciences Western Switzerland, technology, architecture, landscape.CH-1254 Jussy-Geneva, Switzerland.2



ABSTRACT

The pond biodiversity index “IBEM”: a new tool for the rapid assessment of biodiversity in ponds from Switzerland.Part 1. Index development

Due to legal requirements, nature managers increasingly have to carry out assessments of biodiversity for conservation purpo-ses. For ponds, a type of waterbody now widely recognized as an important reservoir for freshwater biodiversity, standardizedbioassessment methods are needed, but still rare. We produced such a tool for small lowland waterbodies in Switzerland: thePond Biodiversity Index (“IBEM”). This Index is the adaptation of a method used by researchers for assessing the biodiver-sity in ponds, PLOCH, which does not currently meet the requirements for routine use by nature managers because it is tooexpensive and requires a high skill level in taxonomic identi�cation. A method intended for practitioners has to be simple,standardized, cheap, adjustable, and consistent with the legislative framework. In order to ful�ll these requirements, the theo-retical and practical aspects of IBEM were developed with a group of representative end users including nature conservationmanagers, consultants, governmental organizations and taxonomic experts. To develop the method, we used a species datasetfrom 63 Swiss lowland ponds which included �ve taxonomic groups: aquatic plants, aquatic Gastropoda, aquatic Coleopte-ra, adult Odonata and Amphibia. The following topics were addressed: (i) the number and type of taxonomic groups whichshould be used for producing the index (is it possible to use surrogates?) (ii) the level of identi�cation for each taxonomicgroup (species? genus? family?) (iii) the sampling strategy (sampling technique, number of replicates), (iv) the calculation ofa unique index and the strategy for assessing its score, and (v) the transfer of this new method to end users. The new methodIBEM uses all �ve taxonomic groups, because a subset of groups did not produce reliable assessments of pond biodiversity.Identi�cation to genus level is required for four groups (aquatic plants, aquatic Gastropoda, aquatic Coleoptera, adult Odona-ta) and species level for Amphibia. The sampling methodology is based on the strati�ed random strategy used in the PLOCHmethod, but with a slight modi�cation in the number of samples per pond. The assessment follows the methodology adoptedby the European Water Framework Directive, and the ratio of the observed richness to a reference-based predicted richnessis translated into one of �ve quality categories for each pond. The �nal index is the mean of the �ve assessment scores. Tofacilitate the implementation of the IBEM method, a website (http://campus.hesge.ch/ibem) enables online calculation of theindex, and provides instructions on both sampling and assessment methodologies. Furthermore, training courses are organizedby the authors of the method for end users.

Key words: Bioassessment, monitoring, small waterbodies, nature conservation, practitioners, macroinvertebrates, aquaticplants, amphibians.

RESUMEN

El �ndice de biodiversidad “IBEM”: una nueva herramienta para evaluar la biodiversidad de charcas en Suiza. Parte I.Desarrollo del �ndice

Debido a requerimientos legales, es cada vez mas necesario que los gestores del medio ambiente lleven a cabo evaluacionesde la biodiversidad dirigidas a la conservacion de la naturaleza. Para las charcas, pequenas masas de agua ampliamente re-conocidas como importantes reservorios de diversidad biologica acuatica, los metodos normalizados de bio-evaluacion son

94 Angelibert et al.

necesarios, pero aun escasos. Para esta tipolog�a de pequenas masas de agua situadas a baja altitud en Suiza se ha elaboradoel �ndice de Biodiversidad de charcas (“IBEM”). Este �ndice es la adaptacion de un metodo utilizado por los investigadorespara evaluar la diversidad biologica en charcas, PLOCH, que no cumpl�a los requisitos para un uso rutinario por parte delos gestores del medio natural por ser demasiado caro y requerir un alto nivel de experiencia en la identi�cacion taxonomica.Un metodo destinado a estos profesionales tiene que ser sencillo, estandarizado, economico, ajustable y en consonancia conel marco legislativo. Con el �n de cumplir estos requisitos, los aspectos teoricos y practicos de IBEM se han desarrolladocon un grupo representativo de posibles usuarios, incluyendo gestores conservadores, consultores, organizaciones guber-namentales y expertos en taxonom�a. Para desarrollar el metodo, se ha utilizado una base de datos de 63 charcas Suizas,situadas en altitudes bajas, que incluye cinco grupos taxonomicos: plantas acuaticas, gasteropodos acuaticos, coleopterosacuaticos, odonatos adultos y an�bios. Se han estudiado los siguientes aspectos: (i) el numero y tipo de grupos taxonomicosque se deben utilizar (es posible el uso de sustitutos?) (ii) nivel de identi�cacion para cada grupo taxonomico (¿especie,genero, familia?) (iii) estrategia de muestreo (tecnica, numero de replicas), (iv) calculo de un �ndice unico y procedimientopara la asignacion de valores y (v) la transferencia de este metodo a los posibles usuarios. El nuevo metodo IBEM utilizalos cinco grupos taxonomicos, ya que un subconjunto de ellos no producir�a evaluaciones �ables de la diversidad biologicade la charca. La identi�cacion a nivel de genero es necesaria para cuatro de estos grupos (plantas acuaticas, gasteropodosacuaticos, coleopteros acuaticos, y odonatos adultos) y para los an�bios es necesario el nivel de especie. El muestreo sigueun diseno aleatorio estrati�cado, utilizado en el metodo PLOCH, pero con una ligera modi�cacion en el numero de muestraspor charca. La evaluacion sigue la metodolog�a adoptada por la Directiva Marco de Aguas, y la relacion entre la riquezaobservada y la del estado de referencia se traduce en una de las cinco categor�as de calidad para cada charca. El �ndice�nal es la media de las cinco puntuaciones de la evaluacion. Para facilitar la aplicacion del metodo IBEM, un sitio web(http://campus.hesge.ch/ibem) permite calculo del �ndice a traves de la red y proporciona instrucciones tanto de las metodo-log�as de muestreo como de la valoracion. Ademas, los autores han organizado cursos de formacion sobre el metodo para losusuarios.

Palabras clave: Indices bioticos, indicadores biologicos, pequenas masas de agua, conservacion de la naturaleza, medioam-bientalistas, macroinvertebrados, plantas acuaticas, an�bios.

INTRODUCTION

Ponds contribute in a unique way to aquatic bio-diversity, supporting as many species as riversor lakes, including many that are rare or threa-tened (Williams et al. 2004, Grillas et al. 2004,Nicolet et al. 2004, Oertli et al. 2004, Angeli-bert et al. 2006). In order to assess and monitorthese freshwater ecosystems, conservation plan-ners and nature managers need to have tools toeasily and rapidly evaluate the biological qua-lity of these aquatic habitats. These rapid biodi-versity assessment tools should be standardized,cheap and consistent with the legislative frame-work. However, such tools are still rare for ponds.Existing methods (e.g. Biggs et al., 2000; Ger-nes & Helgen, 2002; Boix et al., 2005; Chova-nec et al., 2005; Oertli et al., 2005; Solimini etal., 2008; Trigal et al., 2009; Menetrey Perro-tet, 2009) all have features hindering their use bypractitioners from Switzerland. For example, so-me methods apply only to a restricted geographi-cal region, others are too expensive, and many re-

quire a high level of skills in taxonomic identi�-cation (Indermuehle et al., 2004; Sandoz, 2006).In addition, in the absence of simple methodsto assess still waters, managers tend to misusemethods designed for running waters.

The Swiss-based pond biodiversity indexIBEM (from the French Indice de Biodiversi-te des Etangs et Mares) was developed to �ll thisgap. Following suggestions made by Green et al.(2005) to improve biodiversity monitoring, thedevelopment process relied strongly on consul-tations with stakeholders and took into accountthe needs of end users. According to these re-quirements, the new tool had to be: (i) simple interms of sampling and data processing, (ii) stan-dardized, (iii) adjustable, (iv) cheap and (v) euro-compatible. IBEM is based on a method for as-sessing the biodiversity in ponds originally usedby researchers: the PLOCH method (Oertli etal., 2005). PLOCH relies on the species richnessof �ve taxonomic groups: aquatic plants, aqua-tic Gastropoda, aquatic Coleoptera, adult Odona-ta and Amphibia. The choice of these indicator

The IBEM-Index: index development 95

groups has been discussed by Oertli et al. (2005)and supported by further studies (Auderset Jo-ye et al., 2004; Menetrey et al., 2005, 2008).To summarize, the �ve taxonomic groups (aqua-tic plants, aquatic Gastropoda, aquatic Coleop-tera, adult Odonata and Amphibia) ful�ll mostindicator-criteria stated by New (1995) and areecologically complementary with respect to theirlife cycle, their position in the food web, their ha-bitat preferences and their ways of dispersal (forfurther reading on the use of Odonata in bio-diversity assessments, see also Cordoba-Aguilar(2008)). The PLOCH method is relatively expen-sive to use (sampling, sorting and identi�cationtime) and requires species level taxonomic iden-ti�cation skills, and is therefore not suitable foruse by pond conservation practitioners.

A group of experts were consulted throughoutthe development of the IBEM-Index. This groupwas composed of �ve future end users and se-ven taxonomic specialists who were involved inall major decision making. In parallel, �ve teamsof nature conservation managers (three environ-mental consultant teams and two nature reservemanagement groups) tested both the practical andtheoretical aspects of the IBEM method. Theyassessed the method’s strengths and weaknesses,and identi�ed the key issues to be resolved beforesuccessful implementation. Three academic the-ses (Lezat 2006; Sandoz 2006; Frey 2007) were

Figure 1. Distribution of the 63 sampled lowland ponds (cir-cles) in Switzerland with location of the four 4 test ponds (blackcircles). Distribucion de las 63 charcas muestreadas en Suiza(c�rculos) con la localizacion de las 4 charcas de prueba (c�rcu-los negros).

furthermore carried out within the framework ofthe IBEM development. Cross-taxon and within-taxon surrogacies for the �ve taxonomic groupswere also explored using an existing, compatibledataset of 63 ponds. The aim was to determine(i) whether all or a subset of those groups weremandatory for a reliable biodiversity assessment,and (ii) whether a higher taxa approach could beimplemented, i.e. if species level identi�cationcould be replaced by genus or even family levelidenti�cation. The sampling and assessment me-thodologies were then adapted with respect to thechosen taxonomic level. Finally, strategies weredrawn up to implement this new method and ma-ke it easily available to end users.

METHODS

Study sites and practitioner teams

Testing of the method by practitioners was ca-rried out by �ve teams of nature managers: theenvironmental consultants GREN (Geneva, GE),AMaibach Sarl (Oron-la-Ville, VD), NATURA(Les Reussilles, JU) and two nature reserve ma-nagement groups (“Groupe d’Etude et de Ges-tion de la Grande-Caricaie” GEG (Yverdon-les-Bains, VD), and “Fondation des Grangettes/Musee Cantonal de Zoologie de Lausanne” (Lau-sanne, VD)). They applied the PLOCH method(detailed methodology described in Oertli et al.,2005) to assess the biological quality of fourponds located in different regions of WesternSwitzerland (La Grande Caricaie FR, Les Gran-gettes VD, Rouelbeau GE, La Combe TabeillonJU, Fig. 1). These ponds were sampled during2005 or 2006. Experts in the taxonomy and eco-logy of the selected taxonomic groups took partin workshops to provide additional support for thedevelopment of the method: P. Prunier, R. Jugeand J.-B. Lachavanne (aquatic plants), P. Stucki(Gastropoda), G. Carron (Coleoptera), A. Maibach(Odonata) and S. Zumbach/KARCH (Amphibia).

For the development of the IBEM-Index, a da-taset of 63 Swiss lowland ponds (Fig. 1) with analtitudinal range of 305 to 967 m.a.s.l. was used,constituting a subset of the data collected during


the PLOCH project (Oertli et al., 2000; 2002)by the Laboratory of Aquatic Ecology and Bio-logy (LEBA) of the University of Geneva. Themain pond characteristics are given in Appendix1. Sampling of biodiversity (aquatic plants, aqua-tic Gastropoda, aquatic Coleoptera, adult Odona-ta and Amphibia) and measurements of around100 environmental variables were carried out fo-llowing standardized procedures (detailed infor-mation in Oertli et al., 2005).

Developing the IBEM-Index

How many taxonomic groups are required for anaccurate assessment?

In order to investigate if one or more taxonomicgroups can be discarded from the �ve sampledgroups without losing accuracy in the global as-sessment (cross-taxon surrogacy), we measuredthe PLOCH quality class (bad, poor, modera-te, good and high) for 63 lowland ponds, basedon species level data (i) for all �ve taxonomicgroups, and (ii) for all the possible combina-tions using less than �ve groups (n = 30 com-binations). The performance of these 30 combi-nations was then assessed by the percentage ofponds remaining in the same quality class asthat produced by considering all �ve taxonomicgroups (e.g.% of correctly classi�ed ponds).

Choice of taxonomic resolution: species, genusor family?

Species level identi�cation is a time consumingand hence expensive task that requires high ta-xonomic skills often lacking in end users (en-vironmental consultants and other nature mana-gers). For this reason we investigated if speciesrichness could be replaced by genus or even fa-mily richness without losing the relevance of theindex for 63 lowland ponds. This within-taxoninvestigation on surrogacy was carried out intwo steps. Firstly, we tested within-taxon corre-lations, between species, genus or family rich-ness. True richness was calculated by sample-based Jackknife-1 (Burnham & Overton, 1979)estimation for vegetation, Gastropoda and Co-

leoptera. True Odonata richness was estimated byabundance-based Chao-I (Chao, 1984), as the mi-nimal number of replicates (samples) requestedby Jackknife-1 was not available for this group.Jackknife-1 and Chao-1 are both non-parametricestimators, which assess true species richness re-lying on the observed richness measured in the�eld; the use of such true richness estimators re-duces bias linked to heterogeneous sampling ef-fort due to non-exhaustive sampling. The true ri-chness was estimated at all the taxonomic levels(i.e. species, genus and family). A good surroga-te (genus or family richness) should have a goodcorrelation with species richness. The identi�ca-tion levels presenting a low correlation (r2 va-lues below 0.75) were therefore discarded fromfurther analysis. Secondly, the accuracy of theremaining potential surrogates was evaluated bytheir ability to correctly assess pond biodiver-sity. This was done by comparing the real qualityclass of 63 lowland ponds (PLOCH species le-vel assessment) with the quality classes obtainedwith combinations of the different identi�cationlevel (species, genus, family). The performanceof the combinations was evaluated by the percen-tage of the 63 ponds remaining in the same qua-lity class as that produced by considering identi-�cation at the species level for the 5 taxonomicgroups (e.g.% of correctly classi�ed ponds).

Number of samples

The aim of sampling is to gather the observed ta-xonomic richness (Sobs) reaching at least 70% oftrue pond richness (Strue). This level is suf�cientfor subsequently estimating the true richness withrichness estimators. The number of samples (ve-getation plots or macroinvertebrate sweep netsamples) to be collected was assessed with datafrom 63 Swiss lowland ponds. By means of Es-timateS software (Colwell, 2005), 63 accumula-tion curves of Sobs were drawn and Strue was com-putedby thenon-parametric Jackknife-1 estimator(Burnham & Overton, 1979) to compensate forthe bias of a non-exhaustive sampling. This da-ta was then used to estimate the mean number ofsamples necessary to gather at least 70% of Strue(i.e. PLOCH method, Oertli et al., 2005).


Prediction of reference conditions

Biodiversity was assessed by calculating the ra-tio between the observed condition and an unim-paired reference condition. This ratio allowed theclassi�cation of the pond into one of �ve qua-lity classes: bad, poor, moderate, good and high(e.g. the methodology presented in theWFD (EC,2000)). As the -Index is based on taxonomic ri-chness, reference conditions stand for conditionsenabling high potential richness. We predict-ed these reference conditions with GeneralizedAdditive Models (GAMs; Hastie & Tibshirani,1990; Lehmann et al., 2002) built on the rela-tionship between environmental variables and ta-xonomic richness of the �ve indicator groups.Statistical details on the GAM-procedure usedare described by Oertli et al. (2005).

RESULTS

Test of the method by practitioners

The �ve teams of practitioners (environmen-tal consultants and nature reserve managementgroups) all endorsed the concept of a standar-dized sampling approach. They highlighted theusefulness of the rapid assessment index andits euro-compatibility (according to the WFDmethodology). However, two speci�c questionswere raised concerning the proposed taxonomicidenti�cation level (species level) and the num-ber of taxonomic groups to be sampled (�ve). Isspecies identi�cation compulsory for all the bio-logical groups or could genus or even family leveldata do? Could one group (or several groups) beleft aside, depending on the skills of the staff in-volved in the assessment of a given pond? Theseissues were taken into account and tested duringthe further development of the index (see below).Additional questions concerned the fieldworkmethodology, for example the sampling periods tobe chosen or the strategy for sample distribution.These remarks led tomethodological changes in thenewmethod (see Indermuehle et al., 2009).

Furthermore, cost reduction was a central is-sue raised by practitioners during this prelimi-nary test stage. Is it possible to enhance the me-

thod’s cost-effectiveness without affecting thequality of the results? An effort was therefore ma-de to reduce the time necessary for a completepond biological assessment.

Training opportunities were another concernof the practitioners. Above all, they wanted to im-prove �eldwork standardisation (sampling tech-nique and methodology), but also develop theirtaxonomic identi�cation skills.

It was therefore decided to implement an on-line support system, with the objective of impro-ving the use of the index. This interactive website(http://campus.hesge.ch/ibem) contains documents,illustrations and video tutorials, as well as anonline index calculator. Training courses, targe-ted at nature reserve managers and consultantsare also part of the strategy to facilitate imple-mentation of the method in Switzerland.

Developing the index

Cross-taxon investigation: how many taxonomicgroups?

The cross-taxon surrogacy test (with species leveldata) (Fig. 2) showed that the four taxa combi-nation VGCA performed best when compared tothe reference combination (VGCOA, for: Vegeta-tion, Gastropoda, Coleoptera, Odonata, Amphi-bia) with 83% of the ponds correctly classi�edand 17% with only a one-class shift. GCOA per-formed second best (80% of the ponds correctlyclassi�ed), followed by VGCO (73%) and VCA(70%). All single taxa performed badly, with lessthan 45% of the ponds correctly classi�ed.

In conclusion, at least four taxonomic groupswould have to be retained for a reliable assessment,either with the combination VGCA (i.e. withoutOdonata) or GCOA (i.e. without aquatic Vegetation).

Within-taxon investigation: species, genus or fa-mily level?

A total of 243 (= 35) potential combinations wereavailable for this within-taxon investigation, de-pending on the identi�cation level (species, ge-nus or family) of the �ve taxonomic groups.

The �rst step was to test correlations betweenspecies, genus or family richness (Table 1). Spe-


Figure 2. Percentage of correctly classi�ed (“no change”) and misclassi�ed ponds (shifts from one to four classes) obtained bythe assessment with different taxa combinations. V: Vegetation, G: Gastropoda, C: Coleoptera, O: Odonata, A: Amphibia. (n = 63ponds). Porcentaje charcas clasi�cadas correctamente (“sin cambio”) y mal clasi�cadas (cambios de entre una a cuatro categor�as)obtenido a partir de la evaluacion con diferentes combinaciones de los taxones. V: Vegetacion, G: Gastropoda, C: Coleoptera, O:Odonata, A: Amphibia. (n = 63 charcas).

cies richness and genus richness showed strongcorrelations for aquatic Vegetation (r2 = 0.80),Gastropoda (r2 =0.87), Coleoptera (r2 =0.90) andOdonata (r2 =0.88). These results showed that forthese four groups, genus richness could potentiallybe used as a surrogate for species richness. Thiswas not the case for Amphibia (r2 =0.72), whichshould therefore be identified to species level.After discarding 162 combinations involving genusand family richness of Amphibia, only 81 (= 34)remained from the initial 243 combinations.

For correlations between family richness andspecies richness, only Vegetation presented ahigh value (r2 = 0.78); the values for the other ta-xonomic groups were low (r2 from 0.47 to 0.67).Thus, family level cannot be used as surrogate forspecies richness, except possibly for Vegetation.From the 81 original combinations, only 24 re-

mained, involving species level for all 5 groups,genus level for Vegetation, Odonata, Gastropodaand Coleoptera, and family level for Vegetation.

Finally, as species level identi�cation requi-res high taxonomic skills and is likely to hin-der the implementation of a new rapid index, all22 combinations involving species level data forVegetation, Gastropoda, Coleoptera and Odonatawere discarded. Consequently, two combinationsremained: “(VGCO)genus-(A)species” and “(V)family-(GCO)genus-(A)species”. These two su-rrogate combinations differed only in terms ofthe identi�cation level of aquatic Vegetation (V):either family or genus.

The accuracy of these two combinations wasevaluated for their ability to correctly assess thebiodiversity of pond dataset. Compared to the re-ference combination (“VGCOA species”), both

Table 1. Correlations between species richness (S) and genus and family richness of the �ve indicator groups. Correlaciones entrela riqueza de especies (S) y la riqueza de generos y la de familias de los cinco grupos indicadores.

Vegetation S Gastropoda S Coleoptera S Odonata S Amphibia S

Genus richness 0.80 0.87 0.90 0.88 0.72Family richness 0.78 0.47 0.55 0.52 0.67n (ponds) 57 42 62 58 102


Table 2. Percentage of correctly classi�ed ponds for sevendifferent indices. V: Vegetation, G: Gastropoda, C: Coleoptera,O: Odonata, A: Amphibia. Porcentaje de charcas correctamen-te clasi�cadas para siete �ndices diferentes. V: Vegetacion, G:Gasteropodos, C: Coleopteros, O: Odonatos, A : An�bios

Index% of correctlyclassi�ed ponds

(VGCO)genus-(A)species 88%(VGCA)species 83%(V)family-(GCO)genus-(A)species 82%(GCOA) species 79%(VGC)genus-(A)species 72%(GCO)genus-(A)species 72%(V)family-(GC)genus-(A)species 65%

combinations produced satisfying results. The“(VGCO)genus-(A)species” combination perfor-med best, with 88% of the ponds correctly clas-si�ed compared to 82% for the “(V)family-(GCO)genus-(A)species” combination. In both ca-ses, pondsmisclassi�ed only shifted one category.

Taking into account both the cross-taxon and thewithin-taxon investigations

Based on the two previous tests, which inclu-ded discarding some groups and changing thetaxonomic identification level, seven combinations

were considered for the most relevant index(Table 2): “(VGCO)genus-(A)species” and “(V)fa-mily-(GCO)genus-(A)species” (i.e. the two bestcombinations based on all �ve indicator groups),and 5 combinations involving only four indica-tor groups at different taxonomic levels (see pre-vious sections). The combination “(VGCO)ge-nus-(A)species” performed better than the otherindices, with respect to the percentage of co-rrectly classi�ed ponds (88%, Table 2). The se-cond best option was “(VGCA) species”, but thiscombination was discarded because it was basedon species level data and was therefore less sui-table for a rapid index. The combination “(V)fa-mily-(GCO)genus-(A)species” was second equalin effectiveness, but was discounted as it reliedon family level data for Vegetation. Family le-vel identi�cation for plants is likely to be lessintuitive and therefore more time consuming forgeneralists used to genus level identi�cation. Itwas deemed important for the development ofthe Index to �nd a reasonable trade off betweenease of use (e.g. genus level identi�cation) andrelevance for biological assessment; and conse-quently combinations which classi�ed less than80% of sites correctly were considered inadequa-te as indices. For these reasons, the combination

(a) (b)

Figure 3. Mean number of samples necessary to gather at least 70% of Strue as a function of pond area. (a) Aquatic vegetation.Equation of the relationship: n= 30 – 29.1 ∗ log10 (area) + 8.6 * (log10 (area))2. (b) Macroinvertebrates (Coleoptera and Gastropoda).Equation of the relationship: n= 15.5 – 10.5 ∗ log10 (area) + 2.7 * (log10 (area))2. Numero medio de muestras necesarias para obteneral menos el 70% del Strue en funcion del area de la charca. (a) Vegetacion acuatica, ecuacion de la funcion: n= 30 – 29.1 ∗ log10(area) + 8.6 * (log10 (area))2. (b) Macroinvertebrados (Coleoptera y Gastropoda), ecuacion de la funcion: n= 15.5 – 10.5 ∗ log10(area) + 2.7 * (log10 (area))2.


“(VGCO)genus-(A)species” was ultimately cho-sen for the IBEM-Index.

Number of samples

The genus accumulation curves of vegetation andmacroinvertebrates (Gastropoda and Coleoptera)(Sobs) and the associated curves of Strue were com-puted for 63 ponds. This was then used to estima-te the mean number of samples required to reach70% of Strue, in relation to the surface area ofeach of the 63 ponds. These results were used toproduce the relationship between pond area andthe number of samples to be collected (Fig. 3).

Prediction of reference conditions

In order to de�ne the reference conditions andassess the taxonomic richness of the �ve indi-cator groups, �ve predictive models were produ-ced. The relation between environmental varia-bles and the richness of the �ve taxonomic groupswas modelled with GAMs. Out of more than 100local and regional environmental variables, a sub-

set of 15 was selected as potential predictors forthe stepwise selection within the GAM procedu-re. GAMs integrated 12 of these variables, withfour to �ve predictors for each model (Table 3).Area represented the most important contributionto all models, except for Coleoptera, with a con-tribution between 0.63 and 0.93. The other pre-dictors were mean depth, shoreline development,percentage of pond surface shaded by trees, per-centage of woodland in the pond’s surrounding(in a 50-m buffer zone), altitude, �sh presen-ce, proportion of pond area covered by �oating-leaved or submerged vegetation, water conducti-vity, turbidity, and nutrient concentration (trophicstate). Three variables were not integrated in the�ve GAMs: pond connectivity (a measure of iso-lation from other waterbodies), percentage ofagriculture in the catchment area, and pond age.

These �ve models were used to predict re-ference conditions, i.e. highest possible richnessfor each type of pond. For predicting these �-ve richness values for a given pond, 6 of the 12variables, describing the pond typology, have tobe measured in the �eld: pond area, mean depth,

Table 3. Selected predictors and validation diagnostic of the �ve GAM models for aquatic Vegetation, Gastropoda, Coleoptera,Odonata and Amphibia. The range of measured values is presented in Appendix 1. The models were evaluated using percentageof explained deviance (%D), simple variation coef�cient (r1), and cross-validation coef�cient (r2). All models were selected withthreshold p < 0.05. Predictores seleccionados y diagnostico de validacion de los cinco modelos GAM para vegetacion acuatica,gasteropodos, coleopteros, odonatos y an�bios. El rango de valores medidos se presenta en el apendice 1. Los modelos fueronevaluados utilizando el porcentaje de desviacion explicada (% D), el coe�ciente de variacion (r1), y el coe�ciente de validacioncruzada (r2). Todos los modelos fueron seleccionados con p < 0.05.

Area#

Meandepth#

SI#

Shade#

Woodland#

Altitude#

Fish

Floatingveget.

Subm

.veget.

Conductivity

Transparency

PNC

%D

r 1 r 2

Vegetation 0.63 0.57 0.35 0.73 0.33 0.29 0.53 0.37Gastropoda 0.93 0.82 0.59 0.39 0.68 0.37 0.61 0.43Coleoptera 0.65 0.40 0.30 0.42 0.32 0.61 0.51Odonata 0.77 0.67 0.36 0.22 0.62 0.80 0.73Amphibia 0.78 0.66 0.32 0.34 0.20 0.46 0.29

Area: log10(area); SI: shoreline index (de�ned in Appendix 1); shade: percentage of pond surface area shaded; woodland: percentage ofwoodland in a 50m radius from the pond edge; �sh: �sh presence; �oating veget: proportion of pond surface area covered by �oating-leavedvegetation; subm. veget.: proportion of pond surface area covered by submerged vegetation; PNC: trophic state (de�ned in Appendix 1).# Variables to be measured for the IBEM pond assessment.Area: log10(area); SI: desarrollo del per�metro (de�nido en el Apendice 1); shade: porcentaje de area de la charca sombreada; woodland:porcentaje de terreno forestal en un radio de 50 m desde el borde de la charca; �sh: presencia de peces; �oating veget.: proporcion de super�ciede la charca cubierta por vegetacion de hojas �otantes; subm. veget.: proporcion de super�cie de la charca cubierta por vegetacion sumergida;PNC: estado tro�co (de�nido en el Apendice 1).# Variables que deben ser medidas para la evaluacion de las charcas con el IBEM.


shoreline index, percentage of pond surface shaded,percentage of woodland in a 50m radius fromthe pond edge, and altitude. The other 6 variablesare potential indicators of pond degradation andare consequently not to be measured on the field:they are set to their “optimal” value, i.e. allowingthe highest possible taxonomic richness for eachtaxonomic group (see Indermuehle et al., 2009).

Cost of the implementation of the IBEM method

The investigations and tests carried out alwayskept in mind that one of the major requests ofpractitioner was low cost. Every effort was there-fore made to reduce the time necessary for a com-plete pond biological assessment. Time reductionwas achieved mainly by allowing a higher ta-xonomic identi�cation level for four taxonomicgroups (i.e. genus instead of species). Anothernoticeable gain was obtained by replacing macro-invertebrate sorting in the laboratory (Gastropodaand Coleoptera) with �eld sorting. For one sam-ple, the reduction in time is about 60% (from 120minutes to 45 minutes). Overall, the time nee-ded to calculate the IBEM-Index was reduced by50% compared to the PLOCH method (50 hoursfor a 5000 m2 waterbody, instead of 100 hours).

DISCUSSION

The IBEM-Index was developed in close colla-boration with future end users in order to meettheir needs. The overall aim was to create a sim-ple, standardized, rapid index to routinely assesspond biodiversity. By pursuing this aim, an im-portant issue arose in de�ning reasonable tradeoff between ease of use (e.g. avoiding specieslevel identi�cation), low cost, and relevance tobiological assessment. During the developmentof the index, each trade off was weighted-upin order to optimize the �nal assessment tool.For example, the combination “(VGCO)genus-(A)species” was chosen over “(VGCOA)species”even though its performance was slightly worse.Thiswas because it required lower taxonomic skills(often lacking in end users) and was less timeconsuming. As time is money, and funding for bio-

diversity assessments is generally lacking, addres-sing the cost issue was essential for a new index.

Cost reduction was one of the most importantconcerns raised by practitioners during the preli-minary test stage. Therefore, this was the focusof effort to reduce the time necessary for a com-plete pond biological assessment. Approximately50 hours are necessary to calculate the Index for a5000 m2 waterbody, including sampling and da-ta processing. Routine monitoring of biologicalquality for running water is in the same range ofcosts. For example, a half-yearly assessment of astream section with the IBGN Index (AFNOR,1992) is estimated to require the same amount oftime (i.e. 50 hrs) for one year.

Another important new feature of the IBEM-Index is its interactive online tutorial website(http://campus.hesge.ch/ibem) with online indexcalculation, developed to enhance the use of theindex. Training courses, targeted at nature reser-ve managers and consultants, are also part of thestrategy to facilitate implementation of the me-thod in Switzerland.

To summarize, the IBEM method is a tool forthe rapid assessment of the biological quality ofSwiss lowland ponds developed for practitioners(see Indermuehle et al., 2009). It produces an indexby assessing the taxonomic richness of a givenpond as an indicator of its overall biodiversity,and is therefore particularly useful for compa-ring ponds in local or regional scale assessments.The index may also, in time, be used for mo-nitoring conservation actions and policy issues.The IBEM-Index has been designed to meet thespeci�c needs of practitioners, and, as an index,constitutes a new tool for nature conservation.

ACKNOWLEDGEMENTS

The IBEM-Index was developed with supportfrom: Groupe d’Etude et de Gestion de laGrande-Caricaie (GEG), Fondation des Granget-tes, Musee Cantonal de Zoologie de Lausan-ne, Swiss Amphibian and Reptile ConservationProgramme (KARCH), University of Geneva-Laboratoire d’Ecologie et Biologie Aquatique(LEBA), Laboratoire des technologies de l’In-


formation (Haute Ecole de Gestion de Geneve),Consulting of�ces AMaibach Sarl, Aquabug,Aquarius, GREN, and Natura.

The study of the Swiss ponds, which made thedevelopment of the IBEM-Index possible, wassupported by many partners: The Swiss FederalOf�ce for the Environment (FOEN), Cantons ofGeneva, Jura, Vaud and Lucerne, Research com-mission of the Swiss National Park and HES-SO// University of Applied Sciences Western Swit-zerland (RCSO RealTech). Moreover we are gra-teful for the data provided by the Swiss Bio-logical Records Center (CSCF) and the SwissFloristic Database (CRSF).

Many thanks to the following persons for theirvarious contributions: Celine Antoine, Domini-que Auderset Joye, Diana Cambin, Gilles Carron,Emmanuel Castella, Jessica Castella, Michael dela Harpe, Raphaelle Juge, Jean-Bernard Lacha-vanne, Anthony Lehmann, Simon Lezat, Natha-lie Menetrey, Jane O’Rourke, Patrice Prunier,Corinne Pulfer, Nathalie Rimann, Mirko Saam,Lionel Sager, Emilie Sandoz. Furthermore, weare grateful to Helen Keeble and Pascale Nicolet(Pond Conservation) for improving the Englishstyle of the manuscript, as well as to two anony-mous reviewers for their helpful comments.

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Appendix 1. Mean values and ranges of 12 variables characterizing 63 ponds. Valores medios y rangos de las 12 variables utilizadaspara la caracterizacion de las 63 charcas.

Variable Unit Mean Minimum Maximum Median

area m2 7939 66 58064 3100mean depth cm 154 32 850 109shoreline index (D)a 1.5 1.0 2.6 2.0

conductivity µS cm−1 446 61 856 254transparency cm 39 4 60 50

trophic class (PNC)b class 3.33 2 4 3.67�oating-leaved vegetation % 35 0 100 49submerged vegetation % 41 0 100 52altitude m.a.s.l. 542 305 967 423pond shadec class 2.2 1 4 3.1woodland (50 m environment) % 37 0 100 50�sh (1: absence; 2: presence) class 1.65 1 2 1.83

a Shoreline index: D = L/(2 ∗ √(π ∗ S), with L = shoreline length (m), S = pond area (m2), π= 3.141b Trophic class PNC: trophic class indicated by total phosphorus, total nitrogen and conductivity: (1) oligotrophic, (2) mesotrophic,(3) eutrophic, (4) hypertrophicc Pond shade: percentage of pond surface area shaded. Four classes: (1) 0%, (2) > 0-5%, (3) > 5-25%, (4) > 25-100%a Desarrollo del per�metro: D = L/(2 ∗ √(π ∗ S), donde L = per�metro (m), S = area de la charca (m2), π= 3.141b Categor�as tro�cas PNC: categor�a tro�ca indicada por el fosforo total, nitrogeno total y conductividad (1) oligotro�co, (2) me-sotro�co, (3) eutro�co, (4) hipertro�co.c Sombreado de la charca: porcentaje de super�cie de la charca sombreada. Cuatro categor�as: (1) 0%, (2) > 0-5%, (3) > 5-25%,(4) > 25-100%


The pond biodiversity index “IBEM”: a new tool for the rapidassessment of biodiversity in ponds from Switzerland.Part 2. Method description and examples of application

Nicola Indermuehle, Sandrine Angelibert, Veronique Rosset & Beat Oertli∗

hepia Geneva, University of Applied Sciences Western Switzerland, technology, architecture and landscape.CH-1254 Jussy-Geneva, Switzerland.2



ABSTRACT

The pond biodiversity index “IBEM”: a new tool for the rapid assessment of biodiversity in ponds from Switzerland.Part 2. Method description and examples of application

Ponds are now widely recognized to contribute signi�cantly to regional freshwater biodiversity. Therefore, tools to easilyand rapidly assess biological quality speci�cally for these aquatic habitats have been increasingly requested by conservationplanners and nature managers. In close association with practitioners, we developed such a method for Switzerland; the pondbiodiversity index “IBEM”. The IBEM-Index is based on the assessment of the taxonomic richness of 5 groups: aquatic vege-tation, Gastropoda, Coleoptera, adult Odonata and Amphibia. No abundance data are necessary and genus level identi�cationis required for all groups except Amphibia (species level). The sampling methodology is a strati�ed random strategy andallows the use of richness estimators to transform the observed taxonomic richness (Sobs) into true taxonomic richness (Strue).As the IBEM assessment follows the methodology presented in the Water Framework Directive, it is based on the calculationof the ratio of true taxonomic richness (Strue) to reference-based predicted richness (Sref). Each of the �ve taxonomic groups isassessed separately and the overall biological quality of any given pond (i.e. the IBEM-Index) is the average of the �ve ratios.This score is later converted into one of �ve quality classes for each pond: bad (0 to 0.2), poor (> 0.2 to 0.4), moderate (> 0.4to 0.6), good (> 0.6 to 0.8), and high (> 0.8 to 1).In this paper, the implementation of the IBEM-Index is described in detail. The sampling methodologies are developed (forthe biodiversity and the environmental variables) as well as the assessment methodology. Finally, two examples are presen-ted in detail, for a “good” quality pond and for a “bad” quality pond. The method implementation also includes a website(http://campus.hesge.ch/ibem) which allows the online calculation of the index, and provides support for both sampling andassessment methodologies to users.The IBEM-Index is a rapid assessment method which gives an overall value of pond biodiversity in terms of taxa richnessand can be used, for example, in regional screenings or site monitoring in Switzerland. Moreover, as biodiversity is generallyrecognized as a good indicator of global ecological quality, the IBEM-Index can also be used to investigate ecosystem quality.

Key words: Bioassessment, monitoring, small waterbodies, nature conservation, case study, practitioners, macroinvertebra-tes, aquatic plants, amphibians.

RESUMEN

Indice de biodiversidad de charcas “IBEM”: una herramienta para la evaluacion rapida de la biodiversidad de charcas enSuiza. Parte 2. Descripcion del metodo y ejemplos de aplicacion

Esta ampliamente reconocido que las pequenas masas de agua (charcas) contribuyen de forma signi�cativa a la biodiversi-dad regional de las aguas dulces. Por tanto, las herramientas que de manera rapida y facil evaluen espec��camente la calidadbiologica de estos habitats acuaticos estan siendo requeridas cada vez mas por profesionales de la gestion y conservacion delmedio natural. En estrecha colaboracion con estos profesionales, se ha desarrollado un metodo de este tipo para Suiza; el�ndice de biodiversidad de charcas “IBEM”. El Indice-IBEM se basa en la evaluacion de la riqueza taxonomica de 5 grupos:vegetacion acuatica, gasteropoda, coleopteros, odonatos (adultos) y an�bios. No son necesarios datos de abundancia y se re-quiere un nivel identi�cacion de genero para todos los grupos excepto para los an�bios (nivel de especie). Se usa un muestreo

106 Indermuehle et al.

aleatorio estrati�cado que permite obtener estimadores para transformar la riqueza taxonomica observada (Sobs) en riquezataxonomica real (Strue). La evaluacion IBEM sigue la metodolog�a de la Directiva Marco del Agua, que se basa en el calculode la relacion entre la riqueza taxonomica real (Strue) y la riqueza esperable en un estado de referencia (Sref). Cada uno delos cinco grupos taxonomicos se evalua por separado y la calidad biologica de una charca determinada (Indice-IBEM) es lamedia de los cinco coe�cientes. Este resultado es posteriormente asignado a una de las cinco clases de calidad: malo (0 a0.2), de�ciente (> 0.2 a 0.4), moderado (> 0.4 a 0.6), bueno (> 0.6 to 0.8), y muy bueno (> 0.8 a 1).En este art�culo, se describe detalladamente la aplicacion del �ndice IBEM y se desarrollan las metodolog�as de mues-treo (para la biodiversidad y las variables ambientales) y de valoracion utilizadas. Por ultimo, se presentan con de-talle dos ejemplos, una charca con “buena” calidad y otra con “mala” calidad. Se incluye tambien una pagina web(http://campus.hesge.ch/ibem), que permite el calculo del �ndice a traves de internet y sirve de apoyo a los usuarios enlas metodolog�as de muestreo y de valoracion.El �ndice IBEM es un metodo de evaluacion rapida que da un valor general de la diversidad biologica de una charca enterminos de riqueza de taxones y se puede utilizar, por ejemplo, a nivel regional o en el seguimiento de una localidad, enSuiza. Ademas, como la biodiversidad es un buen indicador de la calidad ecologica global, el �ndice IBEM tambien se puedeusar para evaluar el estado del ecosistema.

Palabras clave: Indicadores biologicos, seguimiento, charcas, conservacion de la naturaleza, casos de estudio, medioam-bientalistas, macroinvertebrados, plantas acuaticas, an�bios.

INTRODUCTION

Pond ecosystems contribute signi�cantly to re-gional freshwater biodiversity (Nicolet et al.2004, Oertli et al. 2004, Williams et al. 2004, An-gelibert et al. 2006). In the last 15 years, this hasconsistently been shown in many parts of Euro-pe. As a result, tools to easily and rapidly assessthe biological quality of these aquatic habitats ha-ve been increasingly requested by conservationplanners and nature managers.

Method have previously been developed (e.g.Biggs et al., 2000; Boix et al., 2005; Chovanecet al., 2005; Oertli et al., 2005; Menetrey et al.,2008; Solimini et al., 2008), but the characteristicsof many of these (e.g. special type of ecosystems,restricted geographical use, high cost) prevent theiruse by practitioners from Switzerland. To addressthis, we developed such a method specifically for,and in association with Swiss practitioners: thepond biodiversity index “IBEM”. Throughout theprocess, a selection of representative end userssuch as nature conservation managers, consultants,governmental organizations and taxonomic expertswere consulted on the theoretical and practicalaspect of the method in order to fulfill theirrequirements. The IBEM-Index is simple, stan-

dardized, cheap, adjustable and consistent withthe relevant legislative framework (Angelibert etal. 2009). The new method, IBEM, is based onthe biodiversity of five taxonomic groups, fourof which are identified at genus (aquatic plants,aquatic Gastropoda, aquatic Coleoptera, adultOdonata), and one at species level (Amphibia).The sampling methodology is a stratified randomstrategy. The assessment follows the methodologyadopted by the European Water FrameworkDirective, and the ratio of the observed richness toa reference-based predicted richness is convertedinto one of five quality classes for each pond.The final index is the mean of the five assessmentscores. To facilitate the method implementation,a website (http://campus.hesge.ch/ibem) enablesthe calculation of the index online, and providessupport on both sampling and assessment metho-dologies to users. Full details of the developmentof IBEM have been presented in an anotherpaper (part 1, see Angelibert et al., 2009). Inthis paper (part 2), we present the implementationof the IBEM-Index, including the sampling (forbiodiversity and environmental variables) andassessment methodologies. Finally, two detailedexamples are presented, one for a “good” qualitypondandone for a “bad”quality pond.

The IBEM-Index: method description and application 107

RANGE OF APPLICATION (TYPE OFPOND –GEOGRAPHICAL AREAS)

The IBEM-Index can be used to assess pondswith a surface area of 50 m2 to 60 000 m2, anda mean depth between 30 cm and 900 cm.

The method is valid (i) in Switzerland andthe close border regions of neighbour countries(i.e. with a 100 km-wide belt), and (ii) for wa-terbodies situated in the colline or montane al-titudinal belt (300-1000 m.a.s.l.). For other geo-graphical regions (with different species pools),the sampling strategy can be adopted as it standsor easily adapted. However, a different refe-rence system based on biological data or ex-pert knowledge would have to be developedin order to predict the reference richness (Sref)used in the IBEM-Index assessment.

METHOD FOR SAMPLINGBIODIVERSITY AND MEASURINGENVIRONMENTAL VARIABLES

The IBEM-Index for sampling biodiversity hasbeen specifically adapted (see Angelibert et al.,2009) from the PLOCH assessment method (Oertliet al., 2005). The IBEM-Index is based on theassessment of the taxonomic richness of fivegroups: aquatic vegetation, Gastropoda, Coleopte-ra, adult Odonata and Amphibia. The choice ofthese indicator groups has been largely discussedby Oertli et al. (2005) and supported by furtherstudies (Auderset Joye et al., 2004; Menetrey etal. 2005, 2008; see also Cordoba-Aguilar, 2008for Odonata). For Odonata, the adult stage wasselected because identification and sampling areeasier and less expensive than for larvae or exuviae.Moreover, even though allochthonous taxa cangenerate background noisewhen recording an adultassemblage, this noise can be coped with becauseits magnitude does not prevent identification of themain trends (Oertli, 2008). Presence of adults isalso a metric indicating the quality of the environ-ment of a pond (shoreline, helophytic vegetation,buffer area) and has therefore to be considered.

No abundance data is required and taxa iden-ti�cation is to genus level for all groups except

Amphibia (species level). Exotic taxa are not ta-ken into consideration to evaluate the biodiver-sity with the IBEM-Index as they are not re-presentative of the autochtonous biodiversity ofa pond. The IBEM-Index measures the “qua-lity” (and not the functioning of the ecosys-tem) and cannot therefore include exotic spe-cies. The sampling methodology allows the useof richness estimators (Jackknife-1, Burnham &Overton, 1979) to transform the observed taxo-nomic richness (Sobs) into true taxonomic rich-ness (Strue). Finally, this true richness is com-pared to the reference richness (Sref) that wouldbe expected for reference conditions.

Aquatic vegetation

Aquatic plants are sampled once in early July,with square plots (0.5 × 0.5 m) equally distribu-ted along transects which are regularly spacedperpendicular to the longest axis of the pond(see examples in Fig. 4). Areas deeper than 3 mare not sampled. The two square plots locatedat both ends of each transect must be placed di-rectly against the shoreline, covering only the wa-ter (and not the shore). In case of �uctuatingwater level, shoreline square plots must be pla-ced at the usual pond limit. The position of aqua-tic or terrestrial plants can help to locate this li-mit. For example, Mentha aquatica or Veronicabeccabunga are usually located at the shorelinebut with their stems reaching out of the water. Ifthe pond has a dense reedbed or sedges that areimpossible to penetrate, the square plots are lo-cated in front of this area, on the open water. Thenumber of sample plots (n) in relation to pondarea is calculated as follows: n = 30 − 29.1 ∗log10(area) + 8.6 ∗ (log10(area))2 (see part 1, An-gelibert et al. 2009). This number allows enoughdata to be gathered for each pond so that observedaquatic plant richness (Sobs) reaches on average70% of true richness (Strue). In each plot, the pre-sence or absence of aquatic plant genera is recor-ded, with the help a grapnel or an aquascope asnecessary. The depth is recorded in each squareplot, and is later used to calculate the mean ponddepth (see environmental variables section). Onlyaquatic plants are recorded and these are de�ned


as one of 254 species listed in the highest humi-dity class (= 5) by Landolt (1977). This inclu-des true hydrophytes (species submerged or with�oating leaves) and many emergent plants. Tothis ‘aquatic’ species pool were added 22 specieslisted by Landolt (1977) under humidity class4: Juncus effusus, Carex canescens, Carex �a-va, Carex lepidocarpa, Carex nigra, Eleocharisacicularis, Eleocharis quinque�ora, Equisetumpalustre, Galium palustre, Agrostis stolonifera,Juncus conglomeratus, Scirpus sylvaticus, Jun-cus �liformis, Juncus in�exus, Lysimachia num-mularia, Lythrum salicaria, Lysimachia vulgaris,Mentha longifolia, Myosotis scorpioides, Ranun-culus repens, Rorippa palustris, Juncus articu-latus. The Characeae are considered as a singletaxon. In the case of “mixed” genera which in-clude both aquatic and non-aquatic species (suchas Carex sp.), the genus is considered only ifthe observed specimen belongs to an aquatic spe-cies. Exotic species are not taken into account forthe IBEM-Index (for example Elodea nuttallii).In both these instances, a specimen may requireidenti�cation to species level to be either inclu-ded or discarded in the results.

A table with aquatic genera and species takeninto account in the IBEM-Index can be down-loaded from the IBEM website (http://campus.hesge.ch/ibem/�ore.asp).

Gastropoda and Coleoptera

Aquatic Gastropoda and aquatic Coleoptera (lar-vae and adults) are sampled once in early July,with a small-framed hand-net (rectangular fra-me 14 × 10 cm, mesh size 0.5 mm). This sam-pling date was chosen as the best compromisebetween acceptable cost of the method and sa-tisfactory results. Indeed, the sampling of aquaticinvertebrates can be coupled with the samplingof aquatic vegetation. Gastropoda and Coleop-tera are present in the pond all along the year(with the exception of a few Coleoptera families).Furthermore, both adults and larvae of Coleop-tera are sampled, increasing the chance to sam-ple the Coleoptera taxa. The number of requiredsamples (n) in relation to pond area is calcula-ted as follows: n = 15.5 − 10.5 ∗ log10(area) +

2.7 ∗ (log10(area))2 (see part 1, Angelibert et al.2009). This number allows enough data to be ga-thered for each pond so that observed richness(Sobs) reaches on average 90% of true Gastro-poda richness (Strue) and 70% of true Coleopte-ra richness (Strue). Sampling is strati�ed acrossthe dominant mesohabitats. Sediments and algae(except Characeae) are not sampled because oftheir low taxonomic richness for the selected ta-xa. Mesohabitats are divided into two main ca-tegories: (i) shoreline aquatic mesohabitats, and(ii) those occurring between the shoreline (ex-cluding the shoreline itself) to a depth of 2 m(deeper zones are not sampled). Only mesoha-bitats covering more than 1% of the total me-sohabitat area are taken into account and onlythe pond area comprising the mesohabitats lis-ted in Table 1 is considered (this list is alsoavailable on the IBEM website, http://campus.hesge.ch/ibem/coleopteres.asp). Two thirds of thesamples are then allocated to the �rst mesohabi-tat category and the remaining samples are allo-cated to the second. The samples are distributedbetween the mesohabitats in proportion to the co-verage of each, with a minimum of one sampleper mesohabitat. One unit sample consists of theintensive sweeping of the net through the habitatfor 30 seconds. If one mesohabitat is composedof scattered patches, the sampling time (30 s) isdivided into shorter periods and distributed bet-ween patches (= one composite sample). If thenumber of mesohabitats is larger than the num-ber of samples, the surveyor groups together themesohabitats situated in the lowest position inTable 1 (for example: group together mesohabi-tats 3.2.1. and 3.1. (Table 1)) and then sampleseach habitat for 15 s (= one composite sample).If there is one sample to distribute and two ha-bitats have the same coverage, the user has tochoose the habitat listed in the highest positionin Table 1 (for example: hydrophytes (1) are pre-ferred to Helophytes (2); submerged plants (1.1.)are preferred to �oating leaves (1.2.); etc).

Finally, Gastropoda and Coleoptera are sor-ted in the �eld and presence/absence of gene-ra in each sample is recorded in the laboratory.Empty shells of Gastropoda are not sorted. Forinexperienced staff, additional sorting in the la-


Table 1. List of the mesohabitats taken into account for the IBEM-Index sampling method. Two thirds of the samples are allocatedto the habitats occurring at the shoreline (land-water interface) (A); one third of the samples are allocated to the habitats occurringbetween the shoreline and a depth of 2 m (B). Lista de los mesohabitats considerados en el metodo de muestreo del �ndice IBEM. Dosterceras partes de las muestras se obtienen en habitats situados en las orillas (interfaz tierra-agua) (A); un tercio de las muestras seobtiene en habitats entre la orilla y una profundidad de 2 m (B).

Mesohabitats

A. Habitats occurring at the shoreline (land-water interface)

A. 1. Small-sized helophytes (Carex sp., Eleocharis sp., ...)

A. 2. Roots

A. 3. Bare ground

A. 4. Mineral substrate

A. 5. Accumulations of CPOM (Coarse Particulate Organic Matter) (Leaf litter)

A. 6. Large-sized helophytes (Phragmites sp., Phalaris sp., Typha sp., ...)

A. 7. Other

B. Habitats occurring between the shoreline and 2 m depth (excluding the land-water interface and the sediments)

A. 1. Hydrophytes

A. 1. 1.1.1.1. Submerged with strongly dissected leaves (Myriophyllum sp., Utricularia sp., Ceratophyllum sp., Ranunculus sp. ...)

A. 1. 1.1.1.2. Submerged with thread-like leaves (Potamogeton pusillus, P. pectinatus, Zanichellia palustris)

A. 1. 1.1.2.1. Submerged with large entire leaves (Sagittaria sp., Potamogeton crispus, P. lucens, P. perfoliatus)

A. 1. 1.1.2.2. Submerged with small entire leaves (Elodea sp.)

A. 1. 1.1.3. Characeae

A. 1. 1.2.1. Floating large leaves (Water lilies, Trappa natans, Hydrocharis sp., Potamogeton natans, Polygonum amphibium, ...)

A. 1. 1.2.2. Floating small leaves (Lemna sp.)

A. 1. 1.3. Moss

A. 1. 1.4. Other hydrophytes (Menyanthes trifoliate, ...)

A. 2. Helophytes

A. 1. 2.1. Reedbed (Glyceria maxima, Phragmites australis, Phalaris sp., Typha sp.)

A. 1. 2.2. Large-sized Scirpus (Scirpus lacustris, ...)

A. 1. 2.3. Flooded sedge formations

A. 1. 2.4.1. Alisma sp., Equisetum sp., ...

A. 1. 2.4.2. Eleocharis sp., small Scirpus sp., Juncus sp.

A. 1. 2.5. Other helophytes

A. 3. Other habitats

A. 1. 3.1. Leaf litter

A. 1. 3.2.1. Loose mineral substrate (sand, gravel)

A. 1. 3.2.2. Consolidated mineral substrate (rock, stones)

A. 1. 3.3. Other

boratory is recommended. Identi�cation can bemade either in the �eld or in the lab on pre-served material. Exotic species are not taken in-to account for the IBEM-Index; consequently itcan be necessary to identify the species of a gi-ven specimen in order to discard an exotic ta-xon (for example Gyraulus parvus). The list ofGastropoda and Coleoptera genera used for theIBEM-Index is available on the IBEM website(http://campus.hesge.ch/ibem/coleopteres.asp).

Odonata

Adult Odonata are sampled twice; at the end ofspring and in mid-summer (Fig. 1). The samplingdates depend on the altitude of the studied pond.Observations are made in plots (10 m × 30 m)distributed along one third of the shore length,including all the occurring habitats (Fig. 2).

At least 3 plots must be distributed alongthe shoreline (i.e. ponds with a shoreline length


Figure 1. Late-spring (1) and mid-summer (2) sampling pe-riods for adult Odonata in relation to altitude. These periodswere identi�ed by means of phenological data on adult Odona-ta provided by the Swiss Biological Records Centre (number ofobservations per species, pooled in function of altitude and da-te). Periodos de muestreo para los odonatos adultos en relacioncon la altitud: �nal de primavera (1) y mediados de verano (2).Estos periodos se han determinado mediante datos fenologicosde odonatos adultos facilitados por el Swiss Biological RecordsCentre (numero de observaciones por especie, agrupados enfuncion de la altitud y fecha).

< 270 m are sampled along more than a third ofthe shoreline). Each plot is sampled for 10 minu-

tes. Sampling day conditions are: (i) air tempera-ture between 20 ◦ and 30 ◦C (approximately bet-ween 11h30 and 16h00), (ii) sunshine and (iii) nowind. Presence of Odonata genera is recordedin each plot using binoculars. If identi�cationis not possible with binoculars, Odonata can becaptured using a butter�y net. Strictly lotic taxa,such as Calopteryx and Cordulegaster, are not re-corded. The list of Odonata genera used for theIBEM-Index is available on the IBEM website(http://campus.hesge.ch/ibem/odonates.asp).

Amphibia

The �eld protocol follows the method by Schmidt(2004), used for the red list update in Switzer-land. Presence of amphibian species is recordedduring four visits (March, April, May and June).Each visit lasts 1 hour. The �rst visit is madeduring the night, the other three at dusk. Stan-dardised sampling conditions are mild nights,

Figure 2. Example of distribution of Odonata plots around a pond with route used by the surveyor. Ejemplo de distribucion de lasbandas de muestreo de odonatos en torno a una charca, con la ruta utilizada por el observador.


with no wind or rain. Sampling after a long pe-riod of drought must be avoided. The amphi-bians (adults, subadults, larvae) are surveyed bymeans of (i) search by �ashlight, (ii) identi�ca-tion of calls, and (iii) dip netting. The two spe-cies Rana esculenta and R. lessonae are consi-dered as one single taxon (green frog complex).The taxonomic reference list, used for the IBEM-Index, is available on the IBEM website (http://campus.hesge.ch/ibem/amphibiens.asp).

Amphibians are a �agship group, often witha central importance for managers. As there isa low number of species, this is the only groupwhere an exhaustive inventory (or nearly so) ispossible. Such exhaustive inventory is particu-larly important for detection of rare species (al-so often threatened). This is, for example, thecase in Switzerland where the gathered specieslist is forwarded to the national managers of theSwiss Amphibian breading sites (the KARCH,Swiss Amphibian and Reptile Conservation Pro-gramme), even though this species list is notuseful for the IBEM index.

Environmental variables

Six environmental variables are measured for theIBEM-Index assessment (see next section): pondsurface area (m2), mean depth (cm), shoreline in-dex, pond shade (4 classes), percentage of wood-land in a 50m radius surrounding the pond, and alti-tude (m.a.s.l.).Methods are summarized inTable 2.

METHOD FOR ASSESSING BIOLOGICALQUALITY

The IBEM assessment follows the methodologypresented in the Water Framework Directive, andis based on the calculation of the ratio betweentrue taxonomic richness (Strue) and reference-basedpredicted richness (Sref). This score is translatedinto one of �ve quality classes for each pond: bad(0 to 0.2), poor (>0.2 to 0.4), moderate (>0.4to 0.6), good (>0.6 to 0.8), and high (>0.8 to1). Each of the �ve taxonomic groups is asses-sed separately and the overall biological qua-lity of any given pond (i.e. the IBEM-Index)is calculated by the average of the �ve ratios.

True taxonomic richness (Strue)

To compensate for the bias of a non-exhaustivesampling, observed taxonomic richness (Sobs)is transformed into true taxonomic richness(Strue) by a statistical estimator (Jackknife-1,Burnham & Overton, 1979). Strue is calcula-ted for aquatic vegetation, Gastropoda, Coleop-tera and Odonata either with speci�c softwa-re (for example EstimateS (Colwell, 2005))or by means of our downloadable MicrosoftEXCEL �le (“calcul richesse Strue”), availableat http://campus.hesge.ch/ibem/calcul.asp. Thesampling of amphibian species is considered tobe exhaustive (or nearly so); therefore the obser-ved Amphibian richness equals Strue.

Table 2. Methods to measure the 6 environmental variables used for the assessment of a given pond by the IBEM-Index. Metodosde medida de las 6 variables medioambientales utilizadas para la valoracion de una charca con el �ndice IBEM.

Variables Units Methods

Pond surface area m2 Calculated using GIS, aerial photography or graph paper

Mean depth cm Mean of the depths recorded in each vegetation square plot1 using a ruler or a handhelddepth sounder

Shoreline index D D = L/(2 ∗ √(π ∗ S) with L = shoreline length (m), S = pond area (m2), π = 3.141

Pond shade Class Vertical projection of the shadow of woody vegetation expressed in four classes:

(1) 0%, (2) >0-5%, (3) >5-25%, (4) >25-100%

Woodland (within 50 m) % Forest coverage in a radius of 50 m around the pond

Altitude m

1 If the pond is deeper than 3 m, additional depth measurements must be carried out.


Predicted taxonomic richness (Sref)

The predicted taxonomic richness for referenceconditions (Sref) is calculated for each taxono-mic group using GAM models, based on a sub-set of 12 predicting variables (see Angelibert etal., 2009 for details). Six of these variables (tro-phic state, transparency, conductivity, percenta-ge of �oating-leaved and submerged vegetation,and �sh presence) potentially describe pond de-gradation; they are therefore used to model re-ference conditions for each site. Indeed, thereference condition of a taxonomic group of agiven pond is simulated by setting these 6 in-dicators of degradation to their “non-degraded”value, i.e. allowing the highest possible taxono-mic richness. The other 6 predictors (surface,mean depth, shoreline development, pond sha-ding, percentage of woodland in a 50 m radius,and altitude) are not sensitive to pond degrada-tion and are therefore set to the �eld-measuredvalues. A downloadable tool calculates Srefautomatically (see next section).

Calculating the IBEM-Index

The IBEM-Index is calculated by a user-friendlytool, either directly online on the IBEM website(http://campus.hesge.ch/ibem/calcul de l indice/initialisation.asp) or by means of a downloadableMicrosoft EXCEL �le (“calcul IBEM v1.0”),available from the same website. The followingelements are required to process the index:(i) true genus richness (Strue) of aquatic vege-tation, Gastropoda, Coleoptera and Odonata,(ii) observed species richness of Amphibia,(iii) 6 �eld-measured environmental variables.The user-friendly tool produces the predictedrichness for each taxonomic group (Sref), calcu-lates the ratio Strue/Sref and �nally computes theIBEM-Index (see example in Fig. 6).

APPLIED EXAMPLES

As a demonstration, two ponds were assessed bythe IBEM-Index and the whole process described

Figure 3. Geographical location of the ponds ZH0002 and ZG0023 in Switzerland. Localizacion geogra�ca de las charcas ZH0002y ZG0023 en Suiza.


Table 3. Values of the six environmental variables measu-red in the two ponds (ZH0002 and ZG0023) and required forthe IBEM assessment. Valores de las seis variables ambienta-les requeridas para el �ndice IBEM, en dos charcas (ZH0002 yZG0023).

Variables Ponds

ZH0002 ZG0023Altitude (m a.s.l.) 435.00 0720.00

Surface area (m2) 640.00 1608.00Mean depth (cm) 107.00 0108.00

Forested surrounding (%) 000.00 0008.00

Shoreline development 001.29 0001.22

Shade (% of the pond shaded) 001.00 0001.00

here. The two ponds, ZH0002 and ZG0023, arelocated in lowland Switzerland (Fig. 3). Theseponds are located in Adlikon (canton of Zurich)and Menzingen (canton of Zoug), respectively.Both waterbodies are relatively small (640 m2 forZH0002 and 1608 m2 for ZG0023). Other physi-cal pond characteristics are presented in Table 3.

Sampling

According to the pond surface area and using themathematical formula presented in the methodsection, aquatic plants were sampled in 16 and25 square plots in ZH0002 and ZG0023, respecti-vely. These square plots were equally distributedalong transects (Fig. 4).

The mathematical formula presented in the me-thod section was used to calculate the numberof samples needed to survey for Gastropodaand Coleoptera: 7 and 10 samples in ZH0002 andZG0023, respectively. The samples were stratifiedacross the dominant mesohabitats (two mesohabi-tats in ZH0002 and 3 in ZG0023) (Fig. 5). Twothirds of the samples (5 and 7 respectively) weredistributed along the shoreline aquatic habitats. Theother third was distributed between the shoreline(excluding the shoreline itself) to a depth of 2 m.

Adult Odonata were sampled in 3 plots dis-tributed along the shoreline (Fig. 5). As thesetwo ponds have a shoreline length < 270 m (e.g.116 m and 124 m for ZH0002 and ZG0023 res-pectively), they were sampled along more than athird of the shoreline.

Amphibian species were recorded as descri-bed in the methods section.

Figure 4. Distribution of square vegetation sampling plotsalong transects in the two ponds ZH0002 (a) and ZG0023 (b).Distribucion de los cuadrados de muestreo de la vegetacionacuatica a lo largo de transectos en las dos charcas ZH0002(a) y ZG0023 (b).

The six environmental variables required forthe assessment by the IBEM-Index were also re-corded (Table 3).

Calculation of the IBEM-Index

The observed taxonomic richness (Sobs) wastransformed into true taxonomic richness (Strue)

Table 4. Values of the observed taxonomic richness (Sobs) andtrue taxonomic richness (Strue) for the two ponds ZH0002 andZG0023. V: aquatic vegetation, G: Gastropoda, C: Coleoptera,O: Odonata, A: Amphibia. Valores de la riqueza taxonomicaobservada (Sobs) y de la riqueza taxonomica real (Strue) paralas dos charcas ZH0002 y ZG0023. V: vegetacion acuatica, G:gasteropodos, C: coleopteros, O: odonatos, A: an�bios.

Ponds Taxonomic group

V G C O A

ZH0002Sobs 10 7.0 08.0 10 5Strue 11 7.9 12.3 12 5

ZG0023Sobs 03 0.0 03.0 08 2Strue 04 0.0 05.8 08 2


Figure 5. Example of distribution of the sweep-net samples for Gastropoda and Coleoptera and plots for adult Odonata in the twoponds ZH0002 (a) and ZG0023 (b). Ejemplo de distribucion de las puntos de muestreo con redes de mano para gasteropodos ycoleopteros y de las bandas de muestreo para odonatos adultos en las dos charcas ZH0002 (a) y ZG0023 (b).

by the statistical estimator Jackknife-1 (Burn-ham & Overton, 1979) (Table 4). These valuesof true richness varied between 5 (Amphibians)and 12.3 (Coleoptera) for pond ZH0002, andbetween 0 (Gastropoda) and 8 (Odonata) forpond ZG0023. A list of the taxa recorded in bothponds is given in Appendix 1.

To calculate the IBEM-Index, we used the Mi-crosoft EXCEL �le “calcul IBEM v1.0” (Fig. 6).The user entered values in the grey cells (six envi-ronmental variables, �ve observed richness), andthe results were automatically produced (Fig. 6,cells Ratio and Quality class). Note that the �vetaxonomic groups had to be used for a reliable


assessment with the IBEM-Index. However, theuser can exclude one or more groups (Fig. 6, cells

Group retained yes/no) in order to get a rough es-timate of the biodiversity value of a pond.

a)

b)

Figure 6. Calculation of the IBEM-Index for the two ponds ZH0002 (a) and ZG0023 (b) using the EXCEL �le “calcul IBEM v1.0”(available in French and translated into English for this example) downloadable at http://campus.hesge.ch/ibem. This calculationcan also be done online at: http://campus.hesge.ch/ibem/calcul de l indice/initialisation.asp. Calculo del �ndice IBEM para las doscharcas ZH0002 (a) y ZG0023 (b) usando el archivo de EXCEL “calcul IBEM v1.0” (disponible en frances y traducido a inglespara este ejemplo) se puede descargar en http://campus.hesge.ch/ibem. Este calculo puede realizarse tambien en la siguiente paginade Internet: http://campus.hesge.ch/ibem/calcul de l indice/initialisation.asp.


ZH0002 has a good overall biological quality(Fig. 6a, IBEM-index = 0.79). In this pond, therewas a high diversity of Odonata and Gastropoda,but aquatic vegetation was moderately diverse.

ZG0023 has a poor overall biologicalquality (Fig. 6b, IBEM-Index = 0.28) mainlydue to the poor aquatic vegetation, Gastropodaand Coleoptera diversity.

DISCUSSION

The IBEM-Index is a rapid assessment methodwhich gives an indication of the value of a pondfor biodiversity based on the number of taxa.It enables the identi�cation of taxon-rich pondecosystems, a task required by the 1992 Con-vention on Biodiversity. The IBEM method canbe used in Switzerland for rapid biodiversity as-sessment, for example in regional surveys or forsite monitoring. It is a reliable indicator of si-te quality, adapted for the assessment or moni-toring of ponds belonging to natural sites of na-tional importance (national inventory of marshes,moorlands, river backwaters, amphibian breedingsites). Besides producing the IBEM-Index, thedatasets collected by the IBEMsampling methodcan later be used to study patterns of taxon ri-chness and similarity between sites. Overall, theIBEM-Index is one of the tools available fornature conservation. For strictly species-relatedconservation issues, other tools which are alsopart of the “nature conservation toolbox” shouldbe used, for example exhaustive inventories orred lists. Each tool has its speci�c objective andshould be used appropriately.

As biodiversity is generally recognized as agood indicator of global ecological quality, theIBEM-Index can also be used to investigate thequestion of ecosystem quality, a central objecti-ve of the WFD. For example, the IBEM-Indexwas calculated for 63 Swiss lowland ponds, re-vealing a high proportion of ponds with poor ormoderate biological quality (49%, Fig. 7). Goodquality was assigned to 38% of the ponds, andonly 13%achieved the High quality class, and no-ne of the assessed ponds were ranked in the lo-wer quality class (i.e. Bad). This highlights that

Figure 7. Biological quality of Swiss lowland ponds (n = 63),evaluated by the IBEM-Index. Estado ecologico de las charcassuizas de baja altitud (n = 63) evaluadas mediante el �ndiceIBEM.

about one pond out of two is actually degraded interms of biodiversity, and this is likely to re�ectglobal ecological quality. In the UK, the Country-side Survey 2007 shows that only 8% of pondsare currently in good condition and that the bio-logical quality of lowland ponds decreased bet-ween 1996 and 2007 (Carey et al., 2008). Themain objective of the WFD is to restore the qua-lity of all waterbodies in Europe by 2015. Ho-wever, in all European countries the implemen-tation of the directive covers only waterbodieswith a surface area greater than 50 ha, therefo-re excluding ponds. Despite this, some Europeanregions are also applying WFD-type evaluationand monitoring programmes to ponds (for exam-ple some Spanish states e.g. Catalonia, Aragon).If Switzerland followed the WFD for small wa-terbodies, according to our results half of Swisslowland ponds would have to be restored to goodquality. Although this is not realistic because ofthe limited funding available for nature conserva-tion and water quality management, our assess-ment shows that it is crucial to raise awarenessof the importance of the conservation of ponds inSwitzerland. Currently, ponds are mainly seen asa habitat for �agship species on the Red List. Inthe future, they should also be considered as animportant element of a global landscape whereall freshwater systems should have good ecolo-gical quality. Moreover, the consideration of thewhole pond network is also very important at


the regional scale. Although the IBEM-Index willnot give a quality value to a regional richness,the taxa list gathered through the IBEM samplingcan be useful to address the question of the pondnetwork richness. For global ecological qualityassessments, the IBEM-Index can be combinedwith metrics recently developed speci�cally forthe assessment of the ecological quality of pondsin Switzerland (see Menetrey et al., 2005, 2008;Sager & Lachavanne, submitted).

The IBEM-Index is valid in Switzerland andthe close border regions of neighbour countries(i.e. with a 100 km-wide belt). In others Euro-pean regions, the sampling strategy and metho-dology can nevertheless be used directly. Con-versely, the assessment of the biological quality(i.e. the calculation of the IBEM-Index) has tobe adapted for each region: a reference condi-tion must be assessed for each pond. The assess-ment of this reference value (i.e. for good eco-logical condition) can be done in four differentways (as speci�ed in the WFD): i) using histo-rical data (from a few years ago to paleoecolo-gical data) on similar ecosystems (same surfacearea, depth, altitude, shoreline) relatively natu-rals (i.e. unimpacted by human activities) at thetime of sampling; ii) using current data on si-milar ecosystems, relatively naturals and locatedin the same region; iii) by consulting taxonomicexperts to de�ne the reference value of richnessor iv) through prediction (i.e. using mathemati-cal model of the relationship between diversityand the driving variables).

ACKNOWLEDGEMENTS

The IBEM-Index was developed with supportfrom: Groupe d’Etude et de Gestion de laGrande-Caricaie (GEG), Fondation des Granget-tes, Musee Cantonal de Zoologie de Lausan-ne, Swiss Amphibian and Reptile ConservationProgramme (KARCH), University of Geneva-Laboratoire d’Ecologie et Biologie Aquatique(LEBA), Laboratoire des technologies de l’In-formation (Haute Ecole de Gestion de Geneve),Consulting of�ces AMaibach Sarl, Aquabug,Aquarius, GREN, and Natura.

The study of the Swiss ponds, which made thedevelopment of the IBEM-index possible, wassupported by many partners: Swiss Federal Of�-ce for the Environment (FOEN), Cantons of Ge-neva, Jura, Vaud and Lucerne, Research commis-sion of the Swiss National Park and HES-SO //University of Applied Sciences Western Switzer-land (RCSO RealTech). Moreover we are gra-teful for the data provided by the Swiss Bio-logical Records Center (CSCF) and the SwissFloristic Database (CRSF).

Many thanks to the following persons for theirvarious contributions: Celine Antoine, Domini-que Auderset Joye, Diana Cambin, Gilles Carron,Emmanuel Castella, Jessica Castella, Michael dela Harpe, Raphaelle Juge, Jean-Bernard Lacha-vanne, Anthony Lehmann, Simon Lezat, Natha-lie Menetrey, Jane O’Rourke, Patrice Prunier,Corinne Pulfer, Nathalie Rimann, Mirko Saam,Lionel Sager, Emilie Sandoz.

REFERENCES

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OERTLI, B. 2008. Dragon�ies in the assessment andthe monitoring of aquatic habitats. In:Dragon�ies-Damsel�ies: Model Organisms for Ecologicaland Evolutionary Research. Cordoba-Aguilar A.(ed.): 79-95. Oxford University Press, Oxford, UK.

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Appendix 1. Taxa recorded in the two test ponds. +: presence. Lista de organismos encontrados en las dos charcas utilizadas deejemplo. +: presencia.

Taxonomic group Genus or species Ponds

ZH0002 ZG0023

Aquatic vegetation Alisma sp. +Carex sp. + +Ceratophyllum sp. +Juncus sp. +Lemna sp. +Lycopus sp. +Lythrum sp. +Mentha sp. +Phragmites sp. + +Potamogeton sp. +Typha sp. +

Gastropoda Ferrissia sp. +Gyraulus sp. +Hippeutis sp. +Physella sp. +Planorbarius sp. +Planorbis sp. +Radix sp. +

Coleoptera Agabus sp. +Dytiscus sp. +Enochrus sp. +Haliplus sp. +Helochares sp. +Hydrophylus sp. +Hydroporus sp. +Hyphydrus sp. +Ilybius sp. +Noterus sp. +Oulimnius sp. +

Odonata Aeshna sp. + +Anax sp. + +Coenagrion sp. + +Cordulia sp. +Enallagma sp. + +Erythromma sp. +Ischnura sp. + +Libellula sp. + +Pyrrhosoma sp. +Sympecma sp. +Sympetrum sp. + +

Amphibia Bufo bufo + +Hyla arborea +Green frog complex (Rana esculenta and R. lessonae) +Rana temporaria + +Triturus alpestris +


Designing a standardised sampling method for invertebratemonitoring: a pilot experiment in a motorway retention pond

Olivier Scher1,∗, Kate E. McNutt2 and Alain Thiery3

1 Federation des Parcs naturels regionaux de France, 9 rue Christiani, 75018 Paris, France.2 Botanical, Environmental & Conservation Consultants, 27 Upper Fitzwilliam street, Dublin 2, [email protected] UMR CNRS 6116-IMEP, 3 Place Victor Hugo, Case 37, 13331 Marseille cedex 03, France. [email protected]



ABSTRACT

Designing a standardised sampling method for invertebrate monitoring: a pilot experiment in a motorway retentionpond

The implementation of the European Water Framework Directive revealed the necessity to develop new tools designed forfreshwater ecosystems monitoring. As a new assessment approach employing invertebrate monitoring, three arti�cial substra-tes (two benthic and one pelagic) were tested for 7, 14, 21 and 35 days of exposure in a motorway retention pond located inSouthern France. Two of these arti�cial substrates appeared to sample too narrow a range of taxa, which was con�rmed bytwo-way ANOVA tests and diversity and evenness indices. Samples taken by the remaining arti�cial substrate, composed ofsix plastic plant stems �xed on a 15 × 15 cm square tile, were representative of the species assemblage found in the stormwa-ter retention ponds. The use of an arti�cial substrate as a standardised method for long term invertebrate monitoring in pondsholds much potential.

Key words: Arti�cial substrate, aquatic invertebrates, highway, retention pond, diversity indices.

RESUMEN

Diseno de un metodo de muestreo estandardizado para el seguimiento de invertebrados: experimento piloto en una balsade retencion de autopista

La puesta en marcha de la Directiva Marco Europea del Agua requiere el desarrollo de nuevos protocolos de muestreo parael seguimiento de los ecosistemas acuaticos continentales. Como nuevas aproximaciones al seguimiento de invertebradosacuaticos se probaron tres sustratos arti�ciales (dos benticos y uno pelagico) con un tiempo de exposicion de 7, 14, 21 y35 d�as en una balsa de retencion en una autopista del Sur de Francia. Dos de estos sustratos capturaron selectivamenteun reducido numero de taxones espec��cos, lo que fue con�rmado con un analisis ANOVA de dos factores y los �ndices dediversidad y equitabilidad. Las muestras obtenidas con el sustrato arti�cial compuesto por seis pies de plantas de plastico�jadas en una baldosa cuadrada de 15 × 15 si que resultaron representativas de la asociacion de especies caracter�sticade las balsas de retencion de aguas en las autopistas. El uso de sustratos arti�ciales como metodo estandardizado para elseguimiento a largo plazo de los invertebrados acuaticos en balsas y charcas es de un gran potencial.

Palabras clave: Sustratos arti�ciales, invertebrados acuaticos, autopistas, balsas de retencion, �ndices de diversidad.

122 Scher et al.

INTRODUCTION

During the last few decades many stormwater re-tention ponds have been dug alongside Frenchmotorways following the key aim of the Eu-ropean Water Framework Directive (WFD) toachieve a good ecological water status in Euro-pe by 2015 (European Commission, 2000). Thesebasins act as “road pollutant traps” by collectingsurface runoff during rainstorm events (chronicpollution) or by con�ning accidental and locali-sed pollution. They also play an important rolein regulating water level during the drainage pro-cess. However, the ecological processes withinthem are poorly understood and few studies ha-ve been conducted upon them (Wren et al., 1997;Bishop et al., 2000a, b; Scher & Thiery, 2005).

The need for practical long term monitoringtools in aquatic ecosystems responds to the ob-jective of the WFD. This is particularly impor-tant for stakeholders (public or private) who ha-ve to continuously monitor pond ecosystems inorder to identify potential disturbance linked totheir use (retention, treatment, etc.). Unfortuna-tely, such tools are as yet still rare and not ade-quately designed for non specialists (Oertli etal., 2005). Moreover, a long term monitoringapproach involves regular sampling in the onepond which could disturb the ecosystem whenusing net sampling, a commonly used method.All these arguments show that room exists to de-velop a sampling method that is (1) designed fornon specialists, (2) useful in engineered or dis-turbed environments, (3) low impact on ecosys-tems and (4) standardised. Arti�cial substrates,already used in several aquatic ecosystems, couldrespond to these expectations.

Cairns (1982) defined an artificial substrate as “adevice placed in an aquatic ecosystem to study colo-nization by indigenous organisms”. They have beenintensively used to study colonization processes(estimation of richness, abundance ofmacroinverte-brates, etc.) especially in lotic systems (reviewed inRosenberg & Resh, 1982; Benoit et al., 1998) butonly a few studies exist for shallow lentic habitats(Clarke et al., 1997; Muzzafar & Colbo, 2002).

These devices offer real advantages whencompared to net sampling since they are useful in

habitats that are dif�cult to sample (such as thosewith dense macrophyte beds or concentrated �-lamenteous algae), they are low cost, low-impact(passive sampling), standardised and can be usedfor assessing species richness as well as chan-ges in abundance (Buikema & Voshell, 2001).Nevertheless, they could demonstrate some di-sadvantages such as selectivity and potentialloss of organisms during retrieval of substrates(Rosenberg & Resh, 1982).

Arti�cial substrates used in the study of len-tic systems have encompassed a range of de-signs according to the objectives of the variousstudies, these include rock-bags (De Pauw etal., 1997; Clarke et al., 1997; Muzzafar & Col-bo, 2002), leaf/wood litter bags (France, 1997;Pope et al., 1999) wood snags (Thorp et al.,1985), imitation pondweeds (Jeffries, 1993; Be-noit et al., 1998), multiplate samplers (Francis& Kane, 1995) and cement balls in wire baskets(Schmude et al., 1998). In the present study wechose substrates made of imitation pondweeds(as used in lentic ecosystems by Jeffries (1993)and Benoit et al. (1998)), a scrubbing brush (ne-ver tested) and pan scourers (used in marine ha-bitats to capture meiofauna by Smith & Rule(2002) and Attila et al. (2003)).

The aim of our study was to design a samplingmethod using three different arti�cial substrates(two benthic and one pelagic) placed in a motor-way retention pond over a �ve week period. Theadvantage of designing a sampling method in amotorway pond is the homogeneous conditionsoffered by this ecosystem (Scher, 2005). We �rstcompared the arti�cial substrates on the basis oftheir invertebrate assemblages in order to eva-luate (1) the exposure period necessary to reachequilibrium communities and (2) to assess diffe-rences in richness and diversity. We then com-pared our results with previous sampling effortsconducted in the same pond the previous year inorder to choose the arti�cial substrate most ef-fective at sampling the invertebrate communityof the studied retention pond.

This pilot experiment provides an initial in-sight into the ef�ciency of three arti�cial subs-trates in sampling aquatic invertebrates and theirpotentiality for long term monitoring studies.

A sampling method for invertebrates monitoring 123

Figure 1. Map of study area showing the sampling site.Mapa del area de estudio indicando el punto de muestreo.

METHODOLOGY

Study site

The study was carried out on a stormwater re-tention pond, namely Grans (GR), located inSouth-Eastern France, near Salon-de-Provence(43◦37′43′′N / 05◦03′36′′E, 70 m a. s. l.). The

pond is about 120 × 15 m with a total surfacearea of 1825 m2 and an average depth of 60 cm(Fig. 1). It is filled by storm water and by surfacerunoff from the adjacent A54 motorway (ASF,Autoroutes du Sud de la France) during rainstorms.Violent storm events at the end of summertimeand a drought period are the main characteristicsof the study area, which is under a Mediterranean

124 Scher et al.

climate (Blondel & Aronson, 1999). The groundof the basin is composed of a PEHD (High Den-sity Poly-Ethylene) membrane covered with athin layer (range 0-5 cm) of sediment withoutpebbles or stones. Only hydrophytes (Chara glo-bularis Thuille, Chara vulgaris L., Potamogetonpectinatus L.) and �lamentous algae are present.

Materials

Three types of arti�cial substrates were tested:two benthic ones (the Plastic plant, PL, and theScrubbing brush, BR) placed upon the groundand a single pelagic one (the Pan scourer, PE)maintained in the water column. The PL subs-trate (Fig. 2) was made up of a square tile(15 × 15 cm) to which four plastic stems (39 cmlong) of the model “Indian Cabomba” R©, as wellas two 30 cm long stems and one 20 cm long stemof the model “Ambulia” R© were af�xed. The-se two models, showing the appearance of Cha-ra species, are manufactured by Aqua-Nature R©.When submerged, the stems always stand verti-cally in the water column. The square tile wasused as a weight to keep the substrates at their

chosen positions. As with the PL, the BR substra-te (Fig. 2), made of a scrubbing brush (16 × 6 cmwith a height of 3.5 cm), was �xed to a square ti-le. The �nal substrate, the PE (Fig. 2), was madeof two pan scourers (15 × 9 × 0.7 cm) that we-re inter-locked in their middle to form a cross. Itwas maintained at a chosen depth (about 20 cmunder the surface) by a string secured to a stone.

A total of twenty four samplers were placed inthe pond on the 15th of April 2003. Each of theirpositions was randomly chosen to produce an un-predictable distribution. For each of the four tes-ted exposure lengths (7, 14, 21 and 35 days), twosubstrates of the same type were removed in or-der to allow comparisons of intra-sampler varia-bility. As such a total of six substrates were remo-ved from the basin on each date, placed directlyinto a ziplock R© bag and preserved in 7% formal-dehyde. Utmost care was taken to prevent the lossof invertebrates when retrieving sampling devi-ces (Rosenberg & Resh, 1982).

A set of �ve samples collected every fourweeks in the same retention pond during the year2002 (from March 13 to June 12) was used asa control for sampling procedure. These samples

Figure 2. Schematic of the three arti�cial substrates described in this study with (1) Plastic plant, PL, (2) Scrubbing brush, BR and(3) Pan scourer, PE. Esquema de los tres sustratos arti�ciales empleados en este estudio con (1) Plantas de plastico, PL, (2) Cepillode barrer suelos, BR y (3) Estropajo de �bra limpia-cacerolas.


included three replicates from each date and werecollected using a net of a 125 µm mesh-size withan opening of 21 cm. Total distance swept by thenet, from bottom to surface, was 4 m.

Invertebrate samples were then sorted in thelaboratory and identi�ed to the lowest taxonomiclevel according to Tachet et al. (2002). When thenumber of organisms in a sample was excessi-ve (i.e., as often with Oligochaeta, Cladocera andOstracoda), they were estimated using a Dollfustank that provides a 10% to 11% count error forzooplankton (Pont, 1983).

Abiotic data (electrical conductivity measuredin µS·cm−1 and temperature in ◦C) were measu-red in situ in a single point centred in the pondwith a WTW R© (LF91) device. Depth variation(cm−1) was measured with a graduated ruler pla-ced at the deepest location in the water body. Wa-ter samples were preserved in a refrigerated boxin order to carry them to the laboratory for analy-sis. Anions were analysed by chromatography onDIONEX DX120 and cations by atomic absor-ption on SPECTRA AA 640 VARIAN R©. Watersamples were analysed for herbicides (glyphosa-te and its by-products) by the Departmental La-boratory of Drome (LDA 26) by liquid chroma-tography using �uorogenic labelling.

Analysis

Community structure on each substrate wasanalysed using several methods:

• Taxonomic diversity: total number of taxacollected on each substrate;• Jaccard’s coef�cient (Sj): a measure of si-milarity in species composition between twocommunities (Lincoln et al. 1998);

• Shannon-Wiener index (H′) and Evenness(E): these indices provide information on thestructure and regularity of different samples;

Numeric data were then transformed into den-sity per litre due to the impossibility of esti-mating the surface of the PL substrate. For theplastic plant substrate, each stem was consideredas a cylinder and all stems were summed whilethe two other samplers were considered as cu-bic volumes. The total volume of each substra-te was estimated as 1.583 l for PL, 0.336 l forBR and 0.189 l for PE. Density data were thenlog (x+1) transformed to stabilise variances. Onlythe ten most abundant invertebrate taxa found inthe substrate and net samples were used in theanalyses. Two-way ANOVAs were used to testdifferences among the samples from the three ar-ti�cial substrates. Substrate type and length ofexposure were the two factors tested. The REGWQpost-hoc test was applied to rank treatment fac-tors. Analyses were conducted using XLSTAT c©

for Windows c© software (Addinsoft, 2003).We finally assessed the colonization dynamics

on artificial substrates by drawing accumulationcurves and calculating the number both of taxaacquired and of taxa lost at each substrate betweeneach samplingoccasion (day14, 21 and35).

RESULTS

Chemical data

The principle results are presented in Table 1.During the �ve weeks of the experiment, tem-perature, measured in the morning (between 9

Table 1. Main physical and chemical characteristics of the studied pond during the experiment. Measurements were taken in aunique point centred in the pond. Annual mean refers to previous data published in Scher & Thiery (2005).Principales caracter�sticasf�sicas y qu�micas de la balsadurante el experimento,medidas enunpunto central.Medias anuales extra�das deScher&Thiery (2005).

Conductivity Temperature Depth HCO−3 Cl− NO−3 SO2+4 Ca2+ Glyphosate AMPA

(µS · cm−1) (◦C) (cm) (mg ·L−1) (µg ·L−1)day 7 224 16.4 60 41.48 37 1 3.35 11.95 0.9 < 0.1day 14 284 20.4 58 54.9 53 0 3.05 13.69 0.33 0.17day 21 344 23 55 75.64 55 0 3.25 21.11 0.28 < 0.1day 35 321 23 60 67.1 50 0.9 4.6 19.43 0.25 < 0.1Annual mean 303 17.6 59 53.66 48.98 1.16 4.48 20.14 0.21 0.17

126 Scher et al.

and 10 a.m.), increased continuously from 16 ◦Cto 23 ◦C. Conductivity followed depth variationwith an increase in the concentration of the ma-jor ions (i.e. HCO−3 , Cl

− and Ca2+) followingdrops in water level and their subsequent dilu-tion during the �nal two weeks when the basinwas �lled by rain water and runoff (day 21 to35). Nutrients such as nitrogen, phosphorus andiron were barely detected in the stormwater re-tention pond. Glyphosate molecules along withtheir by-product, the AminoMethylPhosphonicAcid (AMPA), were found in the water columnat low concentration (0.17 to 0.9 µg·l−1) duringthe experiment period. Physical and chemical va-riations of water during the experiment did notdiffer from those recorded during the 2002 sur-vey (Mann-Whitney U-test, p > 0.05). With re-gards to the hydrology of the studied basin, anout�ow originating from the stormwater reten-tion pond and draining into the surrounding land-scape was occasionally observed during the pre-vious survey. When this occurred, it was alwaysresulting from a large rainstorm event. Despi-te the dry summer climate of the studied area,this pond has never dried up since it was dug in1996 (ASF, unpublished data).

Biological data

Taxonomic diversity

The three arti�cial substrates were largely domi-nated by Oligochaetea, Cladocera and Chirono-midae taxa. The total number of organisms oneach substrate ranged from 351 to 1560 on thePL, 580 to 4058 on the BR and from 123 to1176 on the pelagic. In the 2002 survey of Granspond, about 80% of the total organisms caughtby the net sampling were cladoceran. Taxonomicrichness ranged from 34 (BR), 35 (PL) and 40(PE) taxa to 38 taxa in the previous Grans sur-vey. When species composition among the dif-ferent surveys was examined, several differencesbecame apparent. Lymnaea was found solely du-ring the 2002 GR survey and was never sampledby the arti�cial substrates. Coleoptera were oftenabsent from all sampling methods, with the ex-ception of the pelagic substrate after a coloniza-

Table 2. Evolution of Jaccard’s coef�cient of similarity (Sj)of each substrate type (PL = plastic plant, BR = scrubbingbrush, PE = pan scourers) between 7 days of exposure and alltested exposure lengths (14, 21 and 35 days). Evolucion delcoe�ciente de similitud de Jaccard (Sj) en cada tipo de sus-trato (PL=plantas de plastico, BR=cepillo de barrer suelos,PE=estropajo de �bra limpia cacerolas) entre los 7 d�as y losdiferentes periodos de exposicion 14, 21 y 35 d�as).

Sj Coef�cient

day 7 to 14 day 7 to 21 day 7 to 35

PL 0.75 0.64 0.59BR 0.61 0.38 0.45PE 0.63 0.58 0.56

tion period of 21 days. Zygoptera were quick tocolonize all arti�cial substrates and were foundduring the entirety of the experiment, while An-isoptera appeared only after 14 weeks of ex-posure on the BR and the PE. Chironomid ta-xa were apparently much synchronised, showingthe same pattern of appearance/disappearance inall substrates. All substrates showed an increa-se in the number of taxa during the two �rstweeks, followed by stabilization or a decreaseduring the two �nal weeks (Tab. 2).

Jaccard’s coef�cient of similarity

Jaccard’s coef�cient of similarity was used �rstlywithin arti�cial substrates to assess communitydifferences among replicates at each date. Thiscoef�cient, Sj, was always higher than 0.5, in-dicating a high similarity between each of thetwo compared samples (Mann-Whitney U-tests,p > 0.05 in all cases). These results con�rmedthat replicates of each substrate at each sam-pling date always showed similar species pat-terns. Then, by looking at these assemblages du-ring the experiment period, we observed that, foreach tested substrate, Sj decreased from day 7 today 35 with a maximum decrease between day14 and day 21 (Tab. 2) without reaching signi�-cance (Mann-Whitney U-test, p > 0.05). The ta-xa assemblages (coded 0 when a taxon was ab-sent and 1 when present) of each substrate duringall experiment period were compared to the taxapool of this stormwater retention pond found du-ring the previous survey (2002; n = 15; 5 dates ×3 replicates). Similarities among these communi-


Table 3. Evolution of Richness (S), Shannon’s index (H′) andEvenness (E) of each substrate type (PL = plastic plant, BR =scrubbing brush, PE = pan scourers ) in relation to exposurelength. Evolucion de los �ndices: riqueza de especies (S), diver-sidad de Shannon (H′) y equitabilidad (E) para cada sustrato(PL, CR, PE como en la �gura 2).

Substrate Day Number oftaxa (S)

Shannon’sindex (H′)

Evenness(E)

PL 07 24 2.612 0.5714 31 3.373 0.6821 27 2.801 0.5935 26 2.226 0.47

BR 07 22 1.163 0.2614 27 2.199 0.4621 17 0.557 0.1435 22 1.155 0.26

PE 07 20 1.608 0.3714 29 1.286 0.2621 29 1.441 0.3035 30 1.049 0.21

ties were found to be about 72% between the netsampling and the pelagic substrate (PE) and grea-ter than 81% between the net sampling and eachof the other two substrates (BR and PL).

Shannon diversity

The Shannon diversity index (H′) revealed greatdisparity between substrates (Tab. 3). During thecolonization period H′ varied from 2.23 to 3.37 on

the PL substratewhile it was lower for the other twosubstrates: 0.56 to 2.20 for the BR and 1.05 to 1.61for the PE. As for the Shannon index, Evenness (E)washigher in thePL than in the latter two.

ANOVAs

The effects of substrate type and of coloniza-tion time on the abundance of the ten most abun-dant taxa were evaluated (Tab. 4). Substrate ty-pe had a signi�cant effect on the abundance ofseven of these taxa while length of exposurewas only signi�cant for Ostracoda ( p = 0.024)and Cloeon dipterum ( p = 0.029). The REGWQpost-hoc test ranked substrate types according totheir principle effect. Oligochaetea ( p = 0.030)and Cyclopoid ( p = 0.036) appeared to bemore abundant on the BR while Cladocera( p = 0.016), Ostracoda ( p = 0.003), Cloeon dip-terum ( p = 0.010), Heteroptera ( p = 0.010) andHydracarina ( p = 0.010) were more abundanton the pelagic substrate (PE). For all of the-se taxa, the PL substrate appeared to be themost indiscriminate (often ranked in last posi-tion in the REGWQ post-hoc test).

Five taxa (Oligochaetea, Cladocera, Heterop-tera and Chironomidae) were examined morethoroughly at a lower taxonomic level with 2-wayANOVAs and REGWQ post-hoc tests (Tab. 5).

Table 4. Two-way ANOVAs (substrate type and exposure length) and REGWQ post-hoc test results for the densities of the mostabundant taxa (PL = plastic plant, BR = scrubbing brush, PE = pan scourers). Statistical differences (P < 0.05) in the REGWQtest are ranked from highest to lowest (High-Low) density. Resultados del ANOVA de dos factores (tipo de sustrato y tiempo deexposicion) y RGWQ pruebas post-hoc para las densidades de los taxones mas abundantes (PL, CR, PE como en la �gura 2). Lasdiferencias estad�sticas (P < 0.05) de las pruebas RGWQ estan ordenadas de mayor a menor.

Substrate type (PL, BR, PE) Exposure length (7, 14, 21, 35 days)

F value REGWQ F value REGWQmain taxa (High-Low) (High-Low)

Oligochaetea 06.611** BR – (PE, PL) 2.106*Cladocera 08.944** PE – (BR, PL) 2.001*Ostracoda 18.940** PE – (BR –PL) 6.708* (14, 35) – (35, 21, 7)Cyclopoidae 06.063** BR– (PE – PL) 2.277*Cloeon dipterum 10.906** PE – (BR, PL) 6.137* (35, 14) – (14, 21) – 7Caenis 00.775** 0.327*Zygoptera 01.479** 0.262*Heteroptera 11.030** PE – (PL, BR) 0.435*Chironomidae 04.106** 1.679*Hydracarina 10.990** PE – (PL, BR) 4.241*

* = P < 0.05; ** = P < 0.01

128 Scher et al.

Table 5. Two-way ANOVAs (substrate type and exposure length) and REGWQ post-hoc test results for the densities of mostsigni�cant taxa (PL = plastic plant, BR = scrubbing brush, PE = pan scourers). Statistical differences (P < 0.05) in the REGWQpost-hoc test are shown for the groups separated by hiphens and ranked from highest to lowest (High-Low) mean density. Resultadosdel ANOVA de dos factores (tipo de sustrato y tiempo de exposicion) y pruebas post-hoc RGWQ para las densidades de los taxonesmas signi�cativos (PL, CR, PE como en la �gura 2). Las diferencias estad�sticas (P < 0.05) de las pruebas post-hoc RGWQ semuestran para los grupos separados por guiones y ordenados de mayor a menor densidad media.

Substrate type (PL, BR, PE) Exposure length (7, 14, 21, 35 days)

F value REGWQ F value REGWQtaxa (High-Low) (High-Low)

OligochaetaeChaetogaster 11.436*** PE – (PL, BR) 07.057** 14 – (7, 35, 21)Lumbriculidae 05.227*** BR – (PL, PE) 01.076**Tubi�cidae 14.472*** BR – (PL, PE) 00.183**

CladoceraChydorus sphaericus 08.914*** PE – (BR, PL) 09.288** (14, 7) – (35, 21)Pleuroxus aduncus 09.629*** PE – (PL, BR) 01.966**

HeteropteraPlea leachi 06.897*** PE – (PL, BR) 00.886**Naucoris maculatus 26.180*** PE – (PL, BR) 09.189** (21, 35) – (14, 7)

Chironomidae

Tanypodinae A 02.755*** 05.592** (21, 35) – (14, 7)Tanypodinae B 00.884*** 13.474** 35 – (14, 21) – (21, 7)Orthocladiinae 09.836*** PE – (PL, BR) 04.018**Tanytarsini 02.681*** 07.167** 35 – (21, 14) – (14, 7)Chironomus 88.949*** BR – (PL, PE) 01.542**

* = P < 0.05; ** = P < 0.01; *** = P < 0.001

The Oligochete Chaetogaster ( p = 0.009) washighly selected by the pelagic substrate PE, ha-ving achieved a maximum abundance after 14days of exposure ( p = 0.022), while the Tubi�ci-dae ( p = 0.005) and Lumbriculidae ( p = 0.048)were preferentially found in the scrubbing brush,BR. Within the Cladocera, two genus, Chydo-rus ( p = 0.016) and Pleuroxus ( p = 0.013), we-re mostly found on the PE, particularly for Chy-dorus during the �rst 14 days of colonization( p = 0.022). Two true bug species were selectedby the PE substrate, Plea leachi ( p = 0.028) andNaucoris maculatus ( p = 0.001) which were mo-re abundant during the last two weeks of exposu-re ( p = 0.012). Finally, the Chironomidae werealso shown to sometimes be selected for, �rstlyChironomus were found to be highly selectedby the BR ( p < 0.001) and also Orthocladii-nae ( p = 0.013) by the PE. Tanypodinae wereseparated into two types according to the as-pect of their head capsule i.e., long (type A) orshort (type B). Tanypodinae type B ( p = 0.004),type A (P = 0.036) and Tanitarsini ( p = 0.021)were mostly present on all substrates by theend of the experiment (day 35).

Colonization time

Only 14 days of exposure were required in orderto account for 90% of total taxa caught on thetwo benthic substrates, while 21 days were neces-sary for the pelagic substrate (Fig. 3). Moreover,

0

5

10

15

20

25

30

35

40

45

0 10 20 30 40

colonization period (days)

numberoftaxa

PL

BR

PE

Figure 3. Cumulative curve of substrate taxa richness in rela-tion to exposure length. Total number of unique taxa is shown.PL refers to plant substrate, BR to scrubbing brush and PE topan scourer. Curva acumulada de la riqueza de especies en ca-da sustrato en relacion con el tiempo de exposicion. PL, BR yPE como en la �gura 2.


0

2

4

6

8

10

12

day

14

day

21

day

35

day

14

day

21

day

35

day

14

day

21

day

35

PL BR PE

Numberoftaxa

APPEARANCE

DISAPPEARANCE

Figure 4. Histogram presenting taxa appearance and disap-pearance on each substrate in relation to exposure length. Ap-pearance refers to each new taxa found after each exposure pe-riod: 7 to 14 days, 14 to 21 and 21 to 35, while disappearancerefers to each lost taxa after each exposure period. PL refers toplant substrate, BR to scrubbing brush and PE to pan scourer.Histogramas mostrando la aparicion y desaparicion de taxo-nes en cada sustrato en relacion con el tiempo de exposicion.Aparicion se re�ere al numero de taxones nuevos encontradosdespues de cada tiempo de exposicion: desde 7 a 14 d�as , desde14 a 21 y desde 21 a 35 y desaparicion se re�ere al numero detaxones perdidos durante dichos periodos. PL, BR y PE comoen la �gura 2.

many new species had appeared on the substra-tes after 14 days of exposure while many subse-quently disappeared after 21 and 35 days (Fig. 4).

DISCUSSION

The three arti�cial substrates (two benthic andone pelagic) tested for �ve weeks in a motor-way retention pond in southern France showedcontrasting results in terms of invertebrate sam-pling ef�ciency and representativeness of thewhole invertebrate community.

As reviewed by Rosenberg & Resh (1982),most substrates appear to be selective for diffe-rent aquatic invertebrates. In the current experi-ment, organism selectivity was noticed in two ofthe three tested substrates. The PE was highly se-lective for Chaetogaster which is described as aswimmer and a predatory Oligochete (Tachet etal., 2002). This substrate was also preferentia-

lly chosen by two Cladocerans, Chydorus sphae-ricus and Pleuroxus aduncus, this last speciesmainly found on the �oating leaves of hydrophy-tes (Amoros, 1984). Plea leachi and Naucorismaculatus, two predators, were more commonlyfound on the PE, as was also the case for the Or-thocladiinae subfamily mainly composed of mi-crophyte grazers. The complex structure of thepan scourers to which were fastened numerousegg-clutches, probably laid by heteropterans, of-fers a large attachment surface to invertebratesand microphytes. The BR benthic substrate, ma-de of a scrubbing brush, was principally selectivefor oligochetes such as Lumbriculidae and Tubi-�cidae. This last taxa feed on bacteria which de-compose organic matter (Tachet et al., 2002). TheBR also contained numerous individuals of Chi-ronomus, a key genus in eutrophic or disturbedenvironments (Johnson et al., 2001, Pery et al.,2003). This substrate, located on the ground, wasrapidly enveloped by organic matter and �lamen-tous algae. Such material supplies a great sourceof food for scraper species and additionally crea-tes abundant spaces in which organisms can hide.The last substrate, the PL, mock aquatic plantsmade from plastic, appeared to be very indiscri-minate with no particular selectivity for any taxamaking it potentially a good candidate for longterm monitoring. This was also con�rmed by di-versity and evenness indices, always higher forthe PL substrate compared to the two other ones.However, molluscs were absent from all arti�-cial substrates despite occurring in net samples.Such a discrepancy could be explained by the ti-me necessary for molluscs to colonize the subs-trates (particularly in the case of Bivalves suchas Sphaerium) and by their possible loss duringthe retrieval of the samplers, due to their lack ofan adaptation for “clinging”, which has also beennoticed for crustaceans (Rabeni & Gibbs, 1978).

The ef�ciency of arti�cial substrates to col-lect macroinvertebrates is also dependent on thelength of the colonization period (Rosenberg &Resh, 1982). Indeed De Pauw et al. (1986) re-commended a 3 week exposure period due totheir observation that some species only coloni-zed substrates after 2-3 weeks while others ten-ded to disappear after 4 weeks which is consis-

130 Scher et al.

tent with our observations. The pelagic substrate,PE, had the biggest turnover in species compo-sition. This may be explained by its suspensionin the water column which favours its coloniza-tion by very mobile organisms such as Coleopte-ra and Heteroptera. Only active swimmers couldeasily reach such a pelagic device. These speciesalso explain the difference in richness observedbetween this last substrate and the net samplingwhere three coleopterans species were lacking.In all substrates, even though the species com-position tended to stabilise after 35 days of ex-posure, equilibrium did not appear to have beenreached as is often observed in such experiments(De Pauw et al., 1986; Peckarsky, 1986). Con-versely, colonization was shown to be mainly un-der the in�uence of drift processes in lotic sys-tems (Mackay, 1992; Boothroyd & Dickie, 1991;Mihaljevic et al., 1998). This highlights the im-portance of the arti�cial substrate type on coloni-zation in lentic systems.

This pilot study aimed at designing and eva-luating an arti�cial substrates based methodologythat could be useful in long term monitoring ofpond ecosystems. The need for simple and prac-tical monitoring methods has increased these lastyears (following the Water Framework Directiverecommendations), creating room for investiga-tion by scientists. Our previous results suggestthat arti�cial substrates have real potential forpond invertebrate monitoring: they are (1) usableby non specialists, (2) are useful in engineeredor disturbed environments, (3) have a low impacton ecosystem since only arti�cial substrates arecollected and (4) are standardised.

However, even if the arti�cial plant substrate,PL, seems to ful�l monitoring expectations in ourpilot experiment, it is now necessary to test thissubstrate (1) during different seasons in order totake into account species with different life cy-cles, (2) to design a multi-site protocol in orderto evaluate its robustness in various ecosystemsand (3) to compare it with hand-net sampling onthe basis of time and effort required to assess thesame invertebrate community.

Finally, such methods are a fruitful avenue ofinvestigation in the future, particularly for envi-ronmental hazard assessment in aquatic habitats.

ACKNOWLEDGMENTS

This study was funded by a grant (no 609/2001)by the Association Nationale de la RechercheTechnique (ANRT) and the Societe des Auto-routes du Sud de la France (ASF) as a partof O. Scher’s PhD Thesis (http://tel.archives-ouvertes.fr/tel-00109123/en/). We are particu-larly grateful to Jean-Francois Mauffrey, PhilippeCecchi and Marie Bourjade for their useful com-ments on earlier versions of this manuscript. Weare also thankful to the two anonymous refereeswho helped to greatly improve the manuscript.

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Zooplankton community from restored peridunal ponds in theMediterranean region (L’Albufera Natural Park, Valencia, Spain)

Mar�a Anton-Pardo∗ and Xavier Armengol

Department of Microbiology and Ecology. Institut Cavanilles de Biodiversitat i Biologia Evolutiva. University ofValencia, Dr. Moliner, 50, 46100 Burjassot, Valencia, Spain.2



ABSTRACT

Zooplankton community from restored peridunal ponds in the Mediterranean region (L’Albufera Natural Park, Va-lencia, Spain)

The zooplankton of eight restored peridunal ponds located in L’Albufera Natural Park (Valencia, Spain) was sampled fort-nightly from November 2006 to July 2007 to study the effect of hydroperiod, restoration and other environmental variables inthe zooplankton community structure. Ponds with different hydroperiods were selected: two permanent ponds, two temporaryponds with a long hydroperiod (> 6 months a year) and four temporary ponds with short hydroperiod (< 6 months). The timesince they were restored was also different: two of them were only modi�ed; some were restored in the 1990s, and others wereregenerated in recent years (2004-05). The results showed great heterogeneity in the zooplankton community, most probablydue to the strong differences in some limnological variables (mainly conductivity and depth). The dominant group, in termsof density, were the copepods in four ponds, mainly because the high densities of nauplii and copepodites; the rotifers inthree; and cladocerans only in one pond. However, the rotifers presented the highest cumulative richness in all the systems.Species richness in the permanent ponds was higher than in the temporary ones. The main environmental variables affectingthe community composition were depth, highly related to permanence of water, restoration time and conductivity.

Key words: Hydroperiod, peridunal ponds, species richness, zooplankton.

RESUMEN

Comunidad zooplanctonica en charcas peridunares mediterraneas restauradas (Parc Natural de l’Albufera, Valencia,Espana)

El zooplancton de ocho charcas peridunares del Parque Natural de L’Albufera (Valencia, Espana) se siguio quincenalmentedesde Noviembre 2006 a Julio 2007 para conocer el efecto del hidroperiodo, de la restauracion y de otras variables am-bientales en la estructura de la comunidad zooplanctonica. Se estudiaron dos charcas permanentes; dos temporales conhidroperiodo largo (> 6 meses al ano); y cuatro con hidroperiodo corto (< 6 meses). Tambien difer�an en el ano en que fueronrestauradas: dos de ellas exist�an previamente y fueron parcialmente modi�cadas, algunas fueron restauradas en los 90’s, yotras fueron regeneradas mas recientemente (2004-05). Los resultados muestran una gran heterogeneidad en la comunidad dezooplancton debido probablemente a las grandes diferencias en las variables limnologicas, principalmente la profundidad yconductividad. El grupo dominante (en densidad) fueron los copepodos en cuatro de los sistemas, debido a la alta densidad delos nauplios y copepoditos, los rot�feros en tres charcas, y los cladoceros solo en una. Pero en todas las charcas, los rot�ferospresentaron la mayor riqueza acumulada. Las principales variables ambientales en la composicion de la comunidad fueronla profundidad, muy relacionada con la permanencia del agua, la restauracion y la conductividad, ya que en las charcaspermanentes la riqueza espec��ca fue mayor que en las temporales.

Palabras clave: Hidroperiodo, charcas peridunares, rot�feros, riqueza de especies, zooplancton.

134 Anton-Pardo and Armengol

INTRODUCTION

In the Mediterranean region, limnological studieshave shown the great biodiversity of their aqua-tic systems (Quintana et al., 2006; Cereghino etal., 2008). The wide array of ecological factors(depth, hydroperiod, macrophytes, productivityand salinity) that can be found in them (Bekliogluet al., 2007) could explain this fact, by promo-ting a high environmental heterogeneity. In thisregion, temporary ponds are very important foraquatic organisms, due to the scarcity of perma-nent water bodies. A relevant factor in�uencingtheir aquatic community is the duration of thewet phase (or hydroperiod). Inhabitants of theseponds must have adaptations such as rapid life-cycles, diapausing eggs or resting stages (Well-born et al., 1996; Williams, 2000) to ensure thesurvival in the dry phase. The structure of zoo-plankton communites can be in�uenced by se-veral biotic and abiotic factors. Different studieshave suggested the relative importance of someenvironmental variables such as: morphometry,�ooded surface, duration of hydroperiod, trophicstatus, salinity and vegetation cover (e.g. Armen-gol & Miracle, 1999; Boix et al., 2001, Oertli etal., 2002, Eitam et al., 2004, Green et al., 2005,Frisch et al., 2006). Only a few of these studiesinclude rotifers, even though they usually repre-sent the major fraction of zooplankton species ri-

chness (e.g. Fahd et al., 2000; Ortega-Mayagoitiaet al., 2000; Serrano & Fahd, 2005).

In the Valencian Community (Eastern Spain)some of the temporary ponds are peridunal pondslocated in coastal areas. The coastal temporaryponds are considered ecoystems with high spe-cies richness (Lopez et al. 1991; Mazuelos et al.1993; Boix et al., 2007), although some of theiraquatic fauna is still unknown and poorly stu-died (Boix et al., 2001). In L’Albufera NaturalPark, there are many peridunal ponds, where onlyfew studies have been carried out (Soria & Al-fonso 1993; Alfonso, 1996; Rueda-Sevilla et al.,2006). In the 1960s most of these systems wereheavily altered by humans, but in the last twentyyears some of them have been restored. Theseponds are adequate systems to study the in�uenceof natural processes and anthropogenic activitieson the zooplankton community. The main aimof this study is to assess the zooplankton com-munity composition in a selected group of the-se restored peridunal ponds, and to address themain environmental factors which have in�uen-ced their community structure.

STUDY AREA

“Malladas” is the local name of the peridunalponds inL’AlbuferaNatural Park (Valencia, Spain).

Figure 1. Map of the study site. Mapa del area de estudio.

Zooplankton community from restored peridunal ponds 135

They are located in the sandy stretch that separatesl’Albufera, a coastal lagoon, from theMediteraneanSea. They are �lled by rain and ground water.

From the 1960s-1970s most of the ponds andwetlands were silted, but since the late 1980s, se-veral restoration projects have been carried outwith the aim of restoring the original habitat.Therefore, the remains of the antique ponds weredug to different depths, to create both temporaryand permanent ponds.

A set of eight ponds (Fig. 1) was selectedfor this study: two permanent and six temporaryones, showing differences in hydroperiod dura-tion. The ponds were quite close, the longest dis-tance among them is eight km (between LH1and P2). The permanent systems (P1 and P2) ha-ve a dense bed of macrophytes in their centralareas. They house small �sh as Gambusia hol-brooki and the endemic Aphanius iberus (pers.obs.) and amphibians (Rana perezi). The pondP1 was speci�cally restored to be used as a re-fuge for A. iberus, an endangered species. Thetemporary ponds are �shless systems, but hou-se amphibian populations. In this set of tempo-rary ponds, two of them had water more than 7months in the studied period, they were label-led as long hydroperiod (LH1 and LH2), and 4ponds with shorter hydroperiod (SH) had waterless than 6 months in the same period. The pondsdiffered also in the year of restoration: some ofthem (P2, LH1, SH1, and SH4) were totally res-tored in the 1990s; and others (P1, LH2, SH2 andSH3) were restored between 2003 and 2004. P1and SH3 were never completely desiccated andsilted, but through the restoration process theirdepth and water surface increased.

The basic limnological characteristics of someof the ponds were studied in the 1980s, before therestoration project (Soria & Alfonso, 1993; Alfon-so, 1996), and recently only a study on large crusta-ceans (Rueda Sevilla et al., 2006) has been done.

METHODS

The study period started in autumn, when theponds were �lled by rainfall (November 2006).Ponds were sampled fortnightly until they dried

out (or contained less than 5 cm water). For thepermanent ones, sampling �nished in July 2007.

Several variables were measured in situ: con-ductivity, temperature, pH, dissolved oxygen andmaximum depth. One liter water sample was ta-ken at 0.1 m from the surface and �ltered fornutrient and chlorophyll a analysis in the labo-ratory. Chlorophyll a concentration was determi-ned spectrophotometrically from Whatman GF/Fglass �bre �lters, after extraction with 90% ace-tone, following the method of Jeffrey & Hum-phrey (1975). Nitrate and phosphate were measu-red by colorimetry from �ltered samples (Golter-man et al., 1978; APHA, 1980; Murphey &Riley,1962). For all these procedures a Hitachi U2001Spectrophotometer was used.

Zooplankton samples were taken by �ltering,through a 35 µm mesh-size net, a known volu-me of water taken from different sites in theponds. We usually �lter 10 l except when therewere many organisms in the water column, thenthe �ltered volumes were smaller (a minimumof 6 l) to avoid �lter clogging. The organismswere stored in 4% formalin, and identi�ed andcounted in the laboratory using an inverted mi-croscope (Olympus CK40). All the organismsin the samples were counted and, when pos-sible, the individuals were identi�ed to spe-cies level, according to Koste (1978) for roti-fers; Dussart (1967 and 1969) for copepods, andAlonso (1996) for branchiopods. Nauplii, cope-podites and other juveniles were assigned to spe-cies considering adult species proportions.

Some community structure parameters werecalculated: species richness per visit of the threemain groups (rotifers, cladocerans and copepods),mean diversity calculated with Shannon-Wienerindex, and the evenness. A one-way ANOVAwasperformed to see the differences in the measu-res of diversity related with the hydroperiod (inthe permanent, the long hydroperiod, and theshort hydroperiod ponds) and with the differenttime of restoration of the ponds (partially resto-red, restored in the 1990s and recently restored).

For the multivariate analysis, all the environ-mental variables, except pH, and the species den-sities were log transformed. Time since restora-tion was added as a categorical variable in three


Table 1. Mean values and standard deviation (in brackets) of the environmental variables measured during the study period in thedifferent ponds. P: permanent pond; LH: long hydroperiod pond; SH: short hydroperiod pond; Rest: restoration; 1: partially modi�ed;2: restored in 90s; 3: restored in 2003-2004. Valor medio y desviacion t�pica (entre parentesis) de las variables ambientales medidasdurante el periodo de estudio en las diferentes charcas. P: charca permanente; LH: charcas de hidroperiodo largo; SH: charcas dehidroperiodo corto; Rest: restauracion; 1: parcialmente modi�cadas; 2: restauradas en los 90; 3: restauradas en 2003-2004.

Conductivity Temperature pH Oxygen Depth Chl a Nitrate Phosphate RestmS/cm ◦C mg/L cm mg/L mg/L mg/L

P1 1.8 (± 0.2) 17.8 (± 5.5) 8.7 (± 0.3) 9.3 (± 2.4) 110 (± 9) 1.80 (± 1.68) 0.98 (± 0.24) 0.03 (± 0.01) 1P2 4.0 (± 0.4) 16.5 (± 5.5) 8.8 (± 0.4) 8.4 (± 2.4) 114 (± 42) 12.03 (± 16.81) 0.87 (± 0.22) 0.04 (± 0.05) 2LH1 1.5 (± 0.5) 15.9 (± 4.9) 8.2 (± 0.3) 8.9 (± 2.0) 38 (± 9) 1.40 (± 0.97) 1.30 (± 0.92) 0.03 (± 0.01) 2LH2 2.8 (± 1.1) 17.3 (± 3.8) 9.1 (± 0.2) 8.9 (± 1.3) 21 (± 6) 7.82 (± 14.06) 1.07 (± 0.16) 0.03 (± 0.01) 3SH1 1.2 (± 0.3) 16.4 (± 4.6) 8.6 (± 0.3) 8.5 (± 1.4) 11 (± 3) 2.33 (± 1.97) 1.10 (± 0.24) 0.06 (± 0.08) 2SH2 2.0 (± 0.9) 18.3 (± 4.0) 9.1 (± 0.2) 9.7 (± 0.8) 17 (± 5) 4.14 (± 3.94) 1.11 (± 0.28) 0.04 (± 0.03) 3SH3 6.3 (± 1.9) 17.4 (± 3.8) 8.9 (± 0.4) 11.6 (± 1.5) 21 (± 5) 4.81 (± 4.14) 1.08 (± 0.22) 0.12 (± 0.27) 1SH4 0.8 (± 0.3) 13.7 (± 2.7) 8.3 (± 0.2) 9.0 (± 1.5) 14 (± 5) 4.21 (± 2.78) 1.09 (± 0.24) 0.03 (± 0.01) 2

groups: ponds modi�ed; ponds restored in the1990s and ponds restored recently (between 2003and 2004). A CCA was carried out using CANO-CO to detect the patterns of variation in the spe-cies composition and the main relations betweenthe species and each of the environmental varia-bles. Rare species were downweighted and twoMonte Carlo tests (499 permutations) were perfor-med to test the significance of the canonical axes.

RESULTS

Environmental variables

Conductivity in the temporary ponds (Table 1)ranged from 0.43 mS/cm in SH4 in Decem-

ber, to 10.06 mS/cm in November in SH3. Tem-porary ponds showed greater temporal varia-tion than permanent ponds. Depth was positivelycorrelated with water permanence (R2 = 0.78;p < 0.01) and it was higher in the permanentponds (P1 and P2). The pH varied from 8.2 to 9.1and, like the oxygen concentration, which ran-ged from 9.4 mg/l (P2) to 11.6 mg/l (SH3), didnot show a high temporal variation. The nutrientconcentrations were low, varying between 0.87and 1.30 mg/l (nitrate) and between 0.03 and0.12 mg/l (phosphate), with a maximum value ofphosphate of 0.89 mg/l in November in SH3. Thechlorophyll a concentration was slightly higherin P2 and LH2 (maximum of 50 µg/l), which hadalso a higher temporal variation.

0

100

200

300

400

500

600

700

800

P1 P2 LH1 LH2 SH1 SH2 SH3 SH4

meandensity(ind/L)

copepods rotifers

cladocerans anostraca

Figure 2. Mean density (ind/l) of the main zooplankton taxa found in each pond: Permanent ponds (P), long hydroperiod ponds(LH) and short hydroperiod ponds (SH). Densidad media (ind/l) de los principales taxones de zooplancton de cada charca: charcaspermanentes (P), con largo hidroperiodo (LH) y con corto hidroperiodo (SH).


Table 2. List of rotifer, copepod and branchiopod species with an abundance higher than 0.5% and their presence in the ponds.Other species found with an abundance lower than 0.5%: Brachionus angularis, B. calyci�orus, B. ibericus, B. quadridentatus bre-vispinus, B. urceolaris, B. variabilis, Cephalodella cf cyclops, C. cf intuta, C. gracilis, Cephalodella sp., Collotecha sp., Colurellauncinata, Cupelopagis vorax, Encentrum cf marinum, E. saundersiae, Eosphora ehrenbergi, Euchlanis meneta, Lecane cf abanica,L. aculeata, L. curvicornis, L. decipiens, L. grandis, L. hamata, L. hornemanni, L. inermis, L. inopinata, L. lamellata, L. latissima, L.luna, Lepadella acuminata, L. triptera, Lophocaris salpina, Mytilina ventralis, Notholca acuminata, Platyas quadricornis, Pleuro-trocha petromyzon, Proales sp., Ptygura sp., P. cf longicornis, Squatinella rostrum, Testudinella patina, Trichocerca rattus, T. weberi,Trichocerca sp., Tripleuchlanis sp., Horsiella brevicornis, adult Calanoida, adult Harpacticoida, Alona rustica, Pleuroxus aduncus,Daphnia pulicaria, Macrothrix laticornis, Megafenestra aurita, Moina sp., Scapholeberis ramneri and Simocephalus vetulus. Listadode especies de rot�feros, copepodos y branquiopodos con una abundancia mayor de 0.5% y su presencia en las diferentes charcas.Otras especies encontradas con una abundancia menor a 0.5% fueron: Brachionus angularis, B. calyci�orus, B. ibericus, B. qua-dridentatus brevispinus, B. urceolaris, B. variabilis, Cephalodella cf cyclops, C. cf intuta, C. gracilis, Cephalodella sp., Collotechasp., Colurella uncinata, Cupelopagis vorax, Encentrum cf marinum, E. saundersiae, Eosphora ehrenbergi, Euchlanis meneta, Lecanecf abanica, L. aculeata, L. curvicornis, L. decipiens, L. grandis, L. hamata, L. hornemanni, L. inermis, L. inopinata, L. lamellata, L.latissima, L. luna, Lepadella acuminata, L. triptera, Lophocaris salpina, Mytilina ventralis, Notholca acuminata, Platyas quadricornis,Pleurotrocha petromyzon, Proales sp., Ptygura sp., P. cf longicornis, Squatinella rostrum, Testudinella patina, Trichocerca rattus, T.weberi, Trichocerca sp., Tripleuchlanis sp., Horsiella brevicornis, adult Calanoida, adult Harpacticoida, Alona rustica, Pleuroxusaduncus, Daphnia pulicaria, Macrothrix laticornis, Megafenestra aurita, Moina sp., Scapholeberis ramneri y Simocephalus vetulus.

P1 P2 LH1 LH2 SH1 SH2 SH3 SH4

ROTIFERAAnuraeopsis �ssa (Gosse, 1851) 0.6 0.3 0.1 0.1 0.1Bdelloidea 0.7 1.6 0.3 0.7 0.9 5.2 0.1 0.1Brachionus plicatilis (Muller, 1786) 0.2 1.7 0.3 0.1 4.5Cephalodella catellina (Muller, 1786) 0.0 1.3 0.0 0.4 0.1 0.1Cephalodella gibba (Ehrenberg, 1832) 0.1 0.1 0.4 0.3 0.3 3.6Colurella adriatica (Ehrenberg, 1831) 0.5 0.2 0.1 0.1 0.1Colurella colurus (Ehrenberg, 1830) 0.1 0.1 0.1 0.5 0.1 0.7Eosphora najas (Ehrenberg, 1830) 0.7Hexarthra fennica (Levander, 1892) 0.1 11.4 26.4 77.6 11.1 4.8 0.1Hexarthra oxyuris (Sernov, 1903) 4.0Keratella tropica (Apstein, 1907) 1.1 0.2 0.1 0.1 0.1 7.5 0.1Lecane bulla (Gosse, 1851) 0.5 0.1 0.3 0.1Lecane closterocerca (Schmarda, 1859) 0.2 1.8 0.4 0.1Lecane furcata (Murray, 1913) 1.5 0.3Lecane nana (Murray, 1913) 0.1 0.1 0.1 0.2 1.5Lecane punctata (Murray, 1913) 5.7 0.9Lecane pyriformis (Daday, 1905) 0.1 0.1 0.1 0.6Lecane quadridentata (Ehrenberg, 1832) 2.5Lepadella patella (Muller, 1786) 0.2 0.3 6.8 0.1 0.1 2.4 2.0Lindia torulosa (Dujardin, 1841) 0.1 0.1 0.8 1.5 0.1 0.1Notholca squamula (Muller, 1786) 0.1 0.2 0.1 0.5 0.1 0.1Polyarthra dolichoptera (Idelson, 1925) 11.3 2.8 29.4 0.1 0.1 0.1Synchaeta oblonga (Ehrenberg, 1832) 0.1 0.5 5.5Synchaeta pectinata (Ehrenberg, 1832) 3.4 0.1Trichocerca cf elongata (Gosse, 1886) 0.1 0.7 0.1Trichocerca pusilla (Lauterborn, 1898) 0.1 0.5 0.1COPEPODATropocyclops prasinus (Fischer, 1860) 34.2 0.6 3.9Acanthocyclops americanus (Marsh, 1892) 21.1 86.0 56.2 0.4 34.0 26.6 0.2Eucyclops serrulatus (Fischer, 1851) 3.0 0.9 6.2Eucyclops speratus (Lilljeborg, 1901) 2.2 8.0Diacyclops bisetosus (Rehberg, 1880) 15.0 9.1 4.5 55.2 6.0Diacyclops bicuspidatus (Claus, 1857) 4.4 0.4 0.1 80.6Metacyclops minutus (Claus, 1863) 6.7 0.4cf Speocyclops 2.9

Cont.


Table 2. (cont.)

ANOSTRACEATanymastix stagnalis (Linnaeus, 1758) 1.6CLADOCERAAlona rectangula (Sars, 1862) 0.2 1.3 0.1Chydorus sphaericus (Muller, 1776) 0.6 0.2 4.5 0.1 0.2Ceriodaphnia quadrangula (Muller, 1785) 3.2Ceriodaphnia reticulata (Jurine, 1820) 0.7 2.8 0.1Daphnia curvirostris (Eylmann, 1887) 0.1 4.8 0.2Daphnia magna (Straus, 1820) 2.1 4.3 4.2 31 0.1 0.1Moina macrocopus (Straus, 1820) 1.4

Zooplankton community structure

Across the study a total of 100 species werefound: 71 rotifers, 15 cladocerans, 13 copepodsand one anostracan. In the permanent ponds a high-er number of species appeared (Tables 2 and 3).The most common species were bdelloid roti-fers which were present in all studied ponds andAcanthocyclops americanus, Hexarthra fennica,Keratella tropica and Lepadella patella whichwere recorded in seven of the eight ponds.

The highest average zooplankton density(Fig. 2) was found in SH3, (767.8 ind/l), and thelowest in LH1 (116.8 ind/l) (Fig. 2). The do-minant group varied among the ponds: in the per-manent ponds (P1 and P2), and two of the shortperiod temporary ones (SH3 and SH4), thecopepods (mainly larval and juvenile stages)dominated. The short hydroperiod pond SH2 wasthe only one dominated by cladocerans (Daphniamagna). Rotifers were the most abundant group

in the rest of the ponds: planktonic species, suchas Polyarthra dolichoptera and H. fennica, weredominant. The only anostracan species found,Tanymastix stagnalis, occurred in SH1with ameandensity of 6.2 ind/l, mostly in the juvenile stage.

Rotiferswere the groupwith the highest numberof species in all the ponds, with a maximum valueof 47 species in P1, and a minimum of 12 speciesin SH1. Overall, between three and six copepodspecies were recorded per pond, while for thecladocerans, between three (temporary ponds) and11 species (permanent pond, P1)were encountered.

The highest copepod, rotifer and total rich-ness per visit was obtained in P1 (Table 3), whichalso showed a wide range of variation (repre-sented by the high standard deviation). The hig-hest cladoceran richness was found in LH1. Inthe group of ponds with short hydroperiod, SH4had the highest copepod, rotifer and total ri-chness. Diversity calculated with the Shannon-Wiener index ranged from 0.7 bits ind−1 (SH3) to

Table 3. Values of species richness per visit of the main groups of zooplankton, mean diversity (calculated using Shannon-Wienerindex) and mean evenness in the ponds. Valores de riqueza por visita de los principales grupos zooplanctonicos, diversidad promedio(calculada usando el �ndice de Shannon-Wiener) y equitatividad promedio en las lagunas.

Pond Species richness per visit Mean Diversity Evenness

cladocerans copepods rotifers (bits ind−1)

P1 2.7 (± 1.3) 2.1 (± 0.8) 11.9 (± 5.6) 1.3 (± 0.4) 0.3 (± 0.1)P2 0.4 (± 0.6) 0.6 (± 0.6) 11.4 (± 4.8) 1.0 (± 0.6) 0.3 (± 0.2)LH1 3.5 (± 0.9) 1.2 (± 0.8) 10.2 (± 3.2) 1.4 (± 0.6) 0.3 (± 0.3)LH2 1.4 (± 0.8) 1.3 (± 0.8) 4.0 (± 1.9) 0.8 (± 0.4) 0.4 (± 0.2)SH1 0.7 (± 1.1) 1.3 (± 1.0) 5.9 (± 2.6) 1.3 (± 0.7) 0.5 (± 0.2)SH2 0.9 (± 0.6) 0.8 (± 0.9) 5.5 (± 2.3) 1.0 (± 0.3) 0.4 (± 0.1)SH3 0.9 (± 0.6) 1.0 (± 0.7) 5.4 (± 1.9) 0.7 (± 0.4) 0.3 (± 0.1)SH4 0.7 (± 0.8) 2.0 (± 0.6) 9.7 (± 1.2) 1.0 (± 0.6) 0.3 (± 0.2)


1.4 bits ind−1 (LH1). Evenness was low and quitehomogeneous ranging from 0.3 to 0.5.

The results of the ANOVA showed signi�cantdifferences in the species richness between thepermanent and the temporary ponds ( p < 0.05between permanent and long hydroperiod ponds;and p < 0.01 between permanent and short hy-droperiod ponds) and it was higher in the perma-nent ponds. To reduce the effect of the differentsampling effort in the permanent and the tempo-rary ponds, only the dates when all the ponds we-re �lled were compared. The differences in thespecies richness remained signi�cant. With re-gard to the differences in the time since restora-tion, the species richness in the ponds recentlyrestored was signi�cantly lower than in the othertwo groups ( p < 0.01 in both analysis), also ifonly the dates when all the ponds had water werecompared ( p < 0.05 between modi�ed and re-cently restored ponds, and p < 0.01 between res-tored in the 90s and recently restored).

Relationships between zooplankton andenvironmental variables

A total of six environmental variables (depth,conductivity, time since restoration, chlorophyll aand oxygen) as well as 25 zooplankton specieswere retained to perform the CCA. The �rst twoaxes extracted from the CCA accounted for 19%of variance (10.2% of variance the �rst axis and8.8% the second one) and both Monte Carlotests were signi�cant ( p < 0.01). The �rst axis(Fig. 3a) was highly correlated with depth, andseparated the deeper and permanent ponds frommost of the temporary (shallower) ones. The se-cond axis showed higher correlation with con-ductivity, chlorophyll a and oxygen; thus in thepositive region of this axiswere located the systemswith higher values of these variables, in particularconductivity and chlorophyll a (SH3, P2 andLH2).

The species distribution agrees with this or-dination (Fig. 3b); a group of species tolerant tohigher salinity levels, including A. americanus,Brachionus plicatilis or C. adriatica; appearedin the positive region of the second axis wherethe ponds with higher conductivity were distri-buted. The species associated with the permanent

-1.0 1.0-1

.01.0 Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

P1

P2

LH1

LH2

SH1

SH2

SH3

SH4

Axis 1A

xis

2

A

-1.0 1.0-1

.01.0 Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

P1

P2

LH1

LH2

SH1

SH2

SH3

SH4

-1.0 1.0-1

.01.0 Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

P1

P2

LH1

LH2

SH1

SH2

SH3

SH4

Axis 1A

xis

2

A

-1.0 1.0

-1.0

1.0

T. prassinus

A. americanus

D. bisetosus

Harpacticoids

A. fissa

Bdelloids

B. plicatilis

C. gibba

C. adriatica

C. colurus

H. fennica

L. bulla

L. closterocerca

L. hamataL. nana

L. patella

L. salpina

N. squamula

P. dolichoptera

P. longicornis

S. oblonga C. sphaericus

S. vetulus

D. magna

D. curvirostris

Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

Axis

2

Axis 1

B

-1.0 1.0

-1.0

1.0

T. prassinus

A. americanus

D. bisetosus

Harpacticoids

A. fissa

Bdelloids

B. plicatilis

C. gibba

C. adriatica

C. colurus

H. fennica

L. bulla

L. closterocerca

L. hamataL. nana

L. patella

L. salpina

N. squamula

P. dolichoptera

P. longicornis


S. vetulus

D. magna

D. curvirostris

Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

Axis

2

Axis 1-1.0 1.0

-1.0

1.0

T. prassinus

A. americanus

D. bisetosus

Harpacticoids

A. fissa

Bdelloids

B. plicatilis

C. gibba

C. adriatica

C. colurus

H. fennica

L. bulla

L. closterocerca

L. hamataL. nana

L. patella

L. salpina

N. squamula

P. dolichoptera

P. longicornis


S. vetulus

D. magna

D. curvirostris

Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

-1.0 1.0

-1.0

1.0

T. prassinus

A. americanus

D. bisetosus

Harpacticoids

A. fissa

Bdelloids

B. plicatilis

C. gibba

C. adriatica

C. colurus

H. fennica

L. bulla

L. closterocerca

L. hamataL. nana

L. patella

L. salpina

N. squamula

P. dolichoptera

P. longicornis


S. vetulus

D. magna

D. curvirostris

Conductivity

Oxygen

Depth

Chl-a

Rest 90’s

Rest 2000

Axis

2

Axis 1

B

Figure 3. CCA ordination diagram showing the distributionof samples (3a, upper graph) and species position (3b, lowergraph) in relation to environmental variables in the space repre-sented by the two �rst axes. Diagrama de ordenacion del CCAmostrando la distribucion de las muestras (3a, gra�ca superior)y la posicion de las especies (3b, gra�ca inferior) en relacioncon las variables ambientales en el espacio representado porlos dos primeros ejes.

ponds (negative part of the �rst axis), are not onlycharacteristic of open waters (such as the roti-fers P. dolichoptera, Anuraeopsis �ssa and Syn-chaeta oblonga or the copepod T. prasinus) butare also species associated to macrophytes (suchas the rotifers Lophocaris salpina and L. bullaor the cladoceran S. vetulus). Taxa that appea-red in most of the lakes (such as bdelloid roti-


fers or N. squamula) appeared in the centre ofthe �gure. Several littoral species (such as the ro-tifers L. patella, L. nana, C. colurus or the cla-docerans D. curvirostris and C. sphaericus) we-re found associated with the shallowest pondswith the shortest hydroperiods.

DISCUSSION

This studied group of peridunal ponds, all loca-ted in the same area (maximum distance amongthem is less than 8 km), share some basic cha-racteristics in terms of climate and substrate.Nevertheless, a marked temporal and spatial he-terogeneity was found, particularly for limnolo-gical variables such as conductivity, trophic le-vel and duration of the inundation period. Thus,we have found a wide range of variation in theponds which favours the diversity of zooplank-ton species. Some ponds were restored at diffe-rent time, although this is not clear in the lim-nological variables, it seems to have a notoriouseffect on zooplankton community.

Values of speci�c richness per visit, diver-sity and evenness are low, compared with otherstudies in similar ecosystems (e.g. Galindo etal., 1994; Armengol & Miracle, 1999; Rodrigoet al., 2001). This could be related with the resto-ration and subsequent colonization process. Ro-tifers contributed greatly to the community struc-ture in these ponds. Although this group has beenoften neglected in zooplankton studies, they we-re the most diverse group and the most abun-dant in some ponds. This was also the case inmost studies in similar dune ponds, such as theones carried out by Galindo et al. (1994), Fahdet al. (2000) and Serrano & Fahd (2005). Withregard to the crustaceans, it is remarkable thepresence of the anostracean T. stagnalis. It wasfound in only one of the systems, a temporarypond with short hydroperiod (SH1). This lar-ge species can outcompete �lter feeder clado-cerans and rotifers, but it is very sensitive topredation (Bohonak & Whiteman, 1999). Thus,living in temporary ponds, where larger predatorsare frequently absent (Schneider & Frost, 1996),can reduce their risk of predation.

The results of CCA suggest the relevance of con-ductivity and depth, but they have also indica-ted the importance that the restoration processescould have on these communities. Neverthe-less these results should be taken with caution,due to the low number of ponds studied. The re-sults obtained agree with other studies, where theduration of the hydroperiod (here closely rela-ted to depth) could be the main factor determi-ning the structure and composition of the com-munity in aquatic systems (e.g. Wellborn et al.,1996; Boix et al., 2001; Eitam et al., 2004). Ge-nerally, the species richness is higher in perma-nent ponds (e.g. Collison et al., 1995; Alonso,1998; Spencer et al., 1999) or in the temporaryponds with longer hydroperiods (e.g. Boix et al.,2001; Fahd et al., 2000). The comparison bet-ween permanent and temporary water bodies isdif�cult. Obviously the sampling effort (a lon-ger sampling period in permanent ponds) wouldincrease the cumulative speci�c richness. Never-theless, as stated previously, signi�cant differen-ces are still found when only the period with wa-ter in all the ponds was compared.

In this study, permanent ponds recorded thehighest number of species which is probably re-lated to several factors: (i) greater habitat hete-rogeneity, due to the abundance of macrophytesand to the greater depth of these ponds (Crosetti& Margaritora, 1987), (ii) more time to completelife cycles, community development and coloni-zation, (iii) larger diversity of conditions whichcould enable the hatching of more species dia-pausing eggs (iv) abundance of waterfowl, an im-portant vector for the dispersal of zooplanktonin resting stages (e.g. Figuerola & Green, 2002),and �nally, (v) permanent ponds harbour �sh po-pulations and more macroinvertebrate predators(dragon�ies, damsel�ies, water beetles, etc.), sothey have stronger predation pressure, preven-ting the dominance of a few species (Spencer etal., 1999). This can also affect positively small-sized zooplankton species (rotifers and juveni-le copepods), which can better support the pre-datory pressure of �sh (Herzig, 1994), and areinferior competitors to large-sized species (e.g.Gilbert, 1988; MacIsaac & Gilbert, 1991). Follo-wing hydroperiod-depth, conductivity seems to


be the second factor affecting the zooplanktoncommunity. The role of salinity in in�uencing thecommunity structure in ponds has been largelystudied (Williams, 1999; Brock et al., 2005; Tou-mi et al., 2005; Waterkeyn et al., 2008). In thisstudy, salinity (∼ conductivity) negatively affec-ted the species richness, in accordance to other stu-dies (e.g. Boronat et al., 2001; Frisch et al., 2006;Martinoy et al., 2006; Waterkeyn et al., 2008).

In our study, the time since the ponds wererestored is also a very important factor to ex-plain the ordination of samples. Badosa et al.(2006) found a lower biodiversity in old lagoons.In general terms, the opposite was found, be-cause the ponds which were restored recentlyhad lower species richness. The restoration isvery important in terms of community successionand colonization processes, since older pondsfrequently have dense egg banks and, thereforegreater opportunities for hatching.

In conclusion, in our study ponds, the depth,highly related with the permanence of water, hada positive effect on the diversity of aquatic orga-nisms, especially in the permanent ponds, wherethe highest number of zooplankton species wasrecorded, particularly of rotifers. Other factors,such as salinity and the time since the ponds we-re restored, which involve processes such as thetolerance to high salinity levels or the dispersaland colonization processes, also help to better ex-plain the community structure of these peridunalponds. The results obtained here highlighted theimportance of the restoration processes to reco-ver the biodiversity of aquatic systems, particularlyin places heavily affected by human activities.

ACKNOWLEDGEMENTS

We want to thank Andreu Escriva, Carla Olmos,Yasmin Gomez and Laia Zamora for assistance inthe �eld and in the laboratory, as well as the O�-cina Tecnica de la Devesa-Albufera and Genera-litat Valenciana. Deirdre Flanagan and Aline Wa-terkeyn helped to improve the manuscript withlanguage correction and valuable comments. Fi-nancial support for this research was partly pro-vided by a predoctoral grant and the project

CGL2008-03760 from the Ministerio de Cien-cia e Innovacion of the Spanish Government.

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Simulation model comparing the hydroperiod of temporary ponds withdifferent shapes

Alfonso Garmendia1,∗ and Joan Pedrola-Monfort2

1 Instituto Agroforestal Mediterraneo. Departamento de Ecosistemas Agroforestales. Universidad Politecnica deValencia.2 Instituto Cavanilles de Biodiversidad y Biolog�a Evolutiva. Universidad de Valencia. [email protected]



ABSTRACT

Simulation model comparing the hydroperiod of temporary ponds with different shapes

Amodel of the water dynamics for shallow, small and temporary Mediterranean ponds has been developed taking into accountthe annual patterns of rainfall and potential evaporation, pond parameters (pond area, depth and shape) and watershed param-eters (watershed area and saturated water content of the soil). This model predicts the amount of water retained in the pondin real time and therefore, when a pond is going to dry out. It is then possible to calculate how much water will remain in thepond after raining or the number of days per year that the pond is going to be dry. Analyses have been performed for differentshapes of ponds and sensitivity of the state variables, at different values for the parameters. The most interesting result ofour simulations is that the amount of water in the pond (as % of the total) strongly depends on pond shape and maximumdepth and saturated water content of the watershed. Watershed area of the pond will only be important for low intensity rainregimes and for soils with very low saturated water content. Also, the number of days without water (per year) depends onshape and maximum pond depth. Deeper ponds will dry at a slower rate (and therefore have more days with water a year andconsequently shorter drought periods) than shallower ones, independently of their area or the total amount of water. A conicalpond should have more days with water for the same amount of rain, unless the pond does get totally full in each rainfallepisode. Around the Mediterranean Basin, most temporary ponds have a certain degree of arti�ciality (because of agricultureor farms). Thus, this model could help in controlling the hydroperiod by conveniently modifying shapes and depth of ponds tomanage and preserve different species or biotic communities. The simulation model used is freely available from the authorsor in: http://personales.upv.es/∼algarsal/temporary ponds.zip.Key words: Hydroperiod, Hydrologic model, Temporary Mediterranean ponds, Ephemeral wetlands, Pond shape, Temporarypond restoration.

RESUMEN

Modelo de simulacion para comparar el hidroperiodo de las charcas temporales segun su forma

Se ha desarrollado un modelo de dinamica de aguas para charcas pequenas, someras y temporales teniendo en cuenta lospatrones anuales de lluvia y evaporacion potencial, parametros de la charca (area de la charca, profundidad y forma) yparametros de la cuenca de captacion (area de la cuenca y contenido de agua del suelo a saturacion). Este modelo predicela cantidad de agua dentro de la charca en tiempo real y consecuentemente cuando esta va a secarse. Es entonces posiblecalcular cuanta agua permanecera en la charca despues de una lluvia o el numero de d�as por ano que la charca va a estarseca. Se han llevado a cabo diversos analisis para diferentes formas de charcas as� como para comprobar la sensitividadde las variables de estado a diferentes parametros. Lo mas interesante de nuestras simulaciones es que la cantidad de aguadentro de la charca (como % del total) depende estrechamente de la forma de la charca y la profundidad maxima as� comodel contenido de captacion de saturacion de agua en su cuenca de captacion. El area de la cuenca de captacion de la charcasolo sera importante para reg�menes de lluvia de baja intensidad y para suelos que saturan rapidamente (con muy bajocontenido de agua a saturacion). Tambien el numero de d�as sin agua (por ano) depende de la forma y de la profundidadmaxima de la charca. Las charcas profundas se secaran lentamente (y consecuentemente estaran con agua mas d�as alano y por tanto periodos mas cortos de sequ�a) que las someras, independientemente de su area o de la cantidad total

146 Garmendia & Pedrola-Monfort

de agua. Una charca conica debera entonces tener mas d�as con agua para las mismas precipitaciones a menos que lacharca se llene totalmente en cada episodio lluvioso. Alrededor de la Cuenca Mediterranea, la inmensa mayor�a de charcastemporales tienen un cierto grado de arti�cialidad (debido a la agricultura y ganader�a). As�, este modelo podr�a ayudar acontrolar el hidroperiodo a conveniencia modi�cando la forma y profundidad de las charcas para manejar y preservar lasdiferentes especies o comunidades bioticas. El modelo de simulacion utilizado es posible adquirirlo gratis de los autores oen: http://personales.upv.es/∼algarsal/temporary ponds.zip.Palabras clave: Hidroperiodo, modelo hidrologico, charcas temporales mediterraneas, zonas humedas ef�meras, forma de lacharca, restauracion de charcas temporales.

INTRODUCTION

Inevitably, the global population decline of aqua-tic organisms caused by agriculture intensi�ca-tion is a reality and this is not less apparent thanin the decline of amphibian populations (Beja &Alcazar, 2003, Houlahan et al., 2000). Climatechange, too, can have a negative impact uponthese organisms as a result of dramatic changesin levels of precipitation. In order to conservethese organisms and to enhance freshwater bio-diversity, environmental managers need informa-tion and advice on how to manage existing pondsand create new ponds (Williams et al., 2008).

In Mediterranean climate areas, the physio-logically stressful transition between inundationduring the winter growing season and desiccationduring dry summer in shallow, small temporaryponds is the cause for distinctive plant and ani-mal communities (Keeley and Zedler 1998). Un-derstanding hydrologic processes and their depen-dence on morphology of vernal temporary ponds isa fundamental key to manage biotic introductionsand the restoration and creation of new temporarypond ecosystems (Mitsch and Gosselink, 2000).

Some studies based on characterization ofhydrologic conditions within vernal temporaryponds demonstrated the critical role of the hy-droregime in a variety of ecological processes,including dispersal rates, reproductive success,and life history strategies (Gallagher, 1993; Kinget al., 1996; Simovich & Hathaway, 1997; Mar-cus & Weeks, 1997; Morey, 1998; Bohonak &Whiteman, 1999; Snodgrass et al., 1999; Brooks,2000; Stamati et al., 2008). It also correlates

with ecological patterns of species richness andcommunity composition (Crowe et al., 1994;Bliss and Zedler, 1998). These studies usuallyinclude correlations with maximum depth, sur-face area, or short duration observation of hydro-logic conditions, but they have a limited abilityto describe patterns of intra or inter-annual vari-ability. Similar hydrological models have beenmade to �t speci�c goals in particular ponds(Pyke 2004, Zhang et al., 2005) but they didnot study the effect of each pond parameter asregards to the �nal result.

The main aim of this work is to develop asimple water balance model linking weather data(rainfall, potential evapotranspiration) to pondhydroregimes, using the relationships with pondgeometry and size and watershed parameters.This model is necessary for testing the sensitivityof the different pond characteristics against thehydroperiod and detecting which of them are themost sensitive. The �nal goal will be to considerways in which ponds may be modi�ed or createdwith a desired hydroperiod.

The model should allow ef�cient simulationof variations in hydroregime produced by dif-ferent pond characteristics, but to predict ef�-ciently the hydroregime of real ponds it needs tobe calibrated and validated. In order to do this theauthors are undertaking this work in ephemeralvernal ponds in Eastern Spain, as well as encour-aging other workers to use this approach in theirresearch and management activities.

This model is freely available on http://per-sonales.upv.es/∼algarsal/temporary ponds.zip orby contacting the authors.

Hydroperiod simulation model in temporary ponds 147

MATERIAL AND METHODS

Water balance dynamic simulation model

The model is a simple water balance model witha single temporary pond basin as the functionalunit of analysis. A basin receives water inputsfrom direct precipitation and in�ow via the satu-rated watershed, and it loses water through evap-otranspiration and over�ow events. The ground-water is supposed to be impermeable in thismodel, but in cases of changes in water volumenot accounted for by precipitation and evapora-tion, it could be used to estimate seepage.

The following mass-balance mathematicalequation was used to determine the structure ofthe dynamic simulation model for daily waterbudget in the pond:

dνdt= Pν (t) + D(t) − Eν (t) − S(t) (1)

where dν/dt is the rate of change in water volumein the temporary pond, if dν/dt = 0, then inputvalues are equal to output values; Pν (t) is dailyprecipitation over the pond surface; D(t) is dailydrainage to the pond from the watershed; Eν (t) isdaily evapotranspiration on the pond surface; S(t)is Surface over�ow when the pond is full, all ofthem in litres; and t is time (days).

Daily precipitation P(t) and evaporation dataE(t), both are in mm, and should be obtained fromthe closest meteorological station available. For thesensitivity analysis, data for Tortosa were obtainedfrom National Meteorology Institute of Spain.

Watershed

The parameters used to describewatersheds are: thewatershed area WA (m2) and the saturated watercontent FC measured as the maximum amount ofwater that the soil can absorb before it starts tooverflow (l/m2). Therefore, the maximum amountofwater in the soil of the watershedWmax is:

Wmax = WA × FC (2)

The amount of water �owing to the pond fromthe watershed depends on the humidity of the soil

and therefore on the water dynamic in the soil ofthe watershed area. This dynamic is modelled by:

IfW > Wmax, then

dWdt= Pw(t) − Ew(t) − D(t) (3)

else

dWdt= Pw(t) − Ew(t) (4)

where dW/dt is the rate of change in water vol-ume in the soil of the watershed area; Pw(t) isdaily precipitation over the watershed area; Ew(t)is daily evapotranspiration on the watershed sur-face, both of them also in litres; and t is time.

For the Mediterranean ponds under study, allthe water input is from precipitation. Precipita-tion over the watershed produces an increase ofthe amount of water in the soil:

Pw(t) = P(t) ×WA (5)

Evaporation, on the other hand is the mainoutput process:

Ew(t) = WA × E(t) ×(W(t)Wmax

)(6)

whereW(t)/Wmax is a correction factor that reflectsthe fact thatwater evaporates betterwhen soil is sat-urated with water (W(t) = Wmax) and worst as theamount of water lessens. Evaporation is zero whenall possible water is evaporated andW(t) = 0. Thisequation can be simplified using equation (2) to:

Ew(t) =E(t) ×W(t)

FC(7)

Only when W > Wmax, over�ow occurs:

D(t) = W(t) −Wmax (8)

Pond parameters

The parameters used to describe the pond are:MA, maximum area (m2); MD, maximum depth


Figure 1. Pond hydrology simulation model, illustrating: a) STELLA model diagram, b) daily evolution of precipitation and evapo-transpiration for 2005 (evapotranspiration is the daily average from monthly data): evapotranspiration pattern (1), rain pattern (2) andc) amount of water (m3) in the simulated ponds: cylindrical pond (1) and conical pond (2). Modelo de simulacion de la hidrolog�ade una charca, ilustrando: a) el diagrama del modelo en STELLA, b) la evolucion diaria de la precipitacion y la evapotranspiracion(l/m2) para 2005 (la evapotranapiracion es la media diaria extra�da de datos mensuales, l/m2): patron de evapotranspiracion (1),patron de lluvia (2) y c) cantidad de agua (m3) en las charcas simuladas: 1) charca cil�ndrica y 2) charca conica.


(m); andK, shape coef�cient.K represents the re-lationship between pond volume and the volumeof a cylinder and is estimated for each pond as:

K =νmax

MA ×MD (9)

where νmax is the water volume in the pond whenit is at maximum. Therefore, K = 1 for a cylin-drical pond, and K = 1/3 for a conical pond.

Input water in the pond depends on Pν (t) andD(t), and output on Eν (t) and S(t):

Pν (t) = P(t) ×MA (10)

Eν (t) = E(t) × A(t) (11)

S(t) = o, if ν ≤ νmax, and (12)

S(t) = ν − νmax, if ν > νmax (13)

therefore, surface over�ow is fast enough to bedone in one day. It is not representing any narrowchannel, but a wide enough one.

Simulation methods

Simulations were performed using STELLA 8.0,a high-level simulation language (STELLA c©2003, http://www.hps-inc.com). To date, a num-ber of ecological models with wetland hydrol-ogy has been developed using this software (forexample, Zhang & Mitsch 2005). Modelling ofthe temporary ponds dynamics allows to predictthe water dynamics for different ponds shapesand sizes, and to compare the predicted valueswith the real ones. Figure 1 shows the modeland its application to two different pond shapes:cylindrical and conical.

RESULTS AND DISCUSSION

Sensitivity analysis

For the sensitivity analysis of the model we useda typical pond (WA = 5000 m2; FC = 50 l/m2;MA= 200 m2;MD = 20 cm) with real meteorologicaldata from Tortosa, Spain, on 2005, extracted fromNational Meteorology Institute of Spain. At thispoint, small differences are not so important be-

cause the objective is to see how sensitive the statevariables (W and ν) are, to changes in the pa-rameters of the pond and the watershed. For theseanalyses the model has been run with a change inthe parameter of ± 50 % the actual value.

Analysis to test the effect of the pond shape(K) has also been made by modelling a high rain-fall and a drought period afterwards, to see thedrying dynamics and to measure how many dayswithout rainfall each pond will persist. This in-formation on the optimal shape of ponds is ex-tremely important for managers who are activelyinvolved in new pond creation.

The most important parameters for the waterdynamics of the pond are the maximum depth ofthe pond and its shape. Changes produced in thenumber of days with water, the amount of waterin the pond and its depth, are very clear. On theother hand changes on the watershed area, andthe pond area did not change the water dynam-ics of the pond. The dynamics of the amount ofwater in the soil of the watershed is signi�cantlyaffected by the saturated water content, and there-fore this parameter also affects the water dynam-ics of the pond. Surprisingly, it did not affect thenumber of days the pond is dry (Table 1).

Table 1. Sensitivity of the state variables (soil water, W andpond water, v) to changes on the pond and watershed param-eters (± 50 %). “No” means no signi�cant changes and “Yes”signi�cant changes on the dynamics, either with the lesser orthe upper parameter value, or both. W: soil water; v: pond wa-ter; WA: Watershed area; FC: Saturated water content of thewatershed soil; MA: Maximum area of the pond; MD: Max-imum depth of the pond; K: Shape coef�cient of the pond.Sensibilidad de las variables de estado a los cambios en losparametros de la charca y de su cuenca de captacion (± 50 %).“No” signi�ca que no hay cambios signi�cativos y “Yes” sig-ni�ca que hay cambios signi�cativos en su dinamica, tanto conlos valores mas altos o mas bajos del parametro, como con am-bos. W: agua en el suelo; v: agua en la charca; WA: Area dela cuenca de captacion; FC: Contenido de agua a saturaciondel suelo de la cuenca de captacion; MA: Area maxima de lacharca; MD: Profundidad maxima de la charca; K: Coe�cientede forma de la charca.

Sensibility ± 50 %WA FC MA MD K

Days without water No No No Yes Yes

%W No Yes No No No

% V No Yes No Yes Yes

Depth No Yes No Yes Yes


The watershed area is not important in this case,because saturated water content is relatively highand therefore it is necessary for a really heavyrainfall to produce over�ow. When FC is re-duced, over�ow is produced for two rainfall peri-ods in which the pond gets totally full. The com-bined effect of watershed area and FC is not verystrong, because under a heavy rainfall, the pondwill be �lled (or almost �lled) anyway. If thesaturated water content is very low, and water-shed area very high, what occurs is that for al-most every rainfall event, the pond will be totally�lled. This is not very important in the Mediter-ranean climate area, where rain is not very fre-quent, but when it occurs it is usually strongenough to �ll all the ponds, even the ones withvery small watershed areas.

The maximum area of the pond is not impor-tant in the prediction of the number of days withor without water, mainly because water dynam-ics depend mainly on depth. An increase of thevolume of water due to surface increase will notchange the water dynamic because the main inputand output processes are area dependent: precip-itation and evaporation.

Therefore, it can be said that a deep pond(independently of other parameters) is going tolast more that a shallow one, but also the shapeis very important.

Effect of the shape

This effect is general and follows a lineal rela-tionship with K (Fig. 2), but this effect also is de-

0

10

20

30

40

50

60

70

80

90

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

K

Dayswithwater

Figure 2.Linear relationship between K and the number of dayswith water in the simulated pond, for weather at Tortosa in 2005.Relacion lineal entre K y el numero de d�as con agua en lacharca simulada, para el tiempo atmosferico de Tortosa en 2005.

0

10

20

30

40

50

60

0 20 40 60 80 100 120

K=0.33

K=1

Figure 3. Days with water in two ponds with different shapes(cylindrical vs. conical) after rainfall of different intensities.D�as con agua en dos charcas con diferente forma (cil�ndricavs. conica) despues de periodos de lluvia de diferente intensi-dad.

pendent on the amount of rain for each rain-fall episode. The effect of K is most importantfor light rainfall episodes than for heavy rainfallepisodes (Fig. 3). Cylindrical ponds dry fasterthan conical, and this effect is more evident af-ter a shallow rain episode. This occurs becausewhen a conic pond is drying, the actual area ofthe pond and therefore, its evaporation, dimin-ishes. A cylindrical pond has the same area (andhigh evaporation) even with little water.

CONCLUSIONS

This study has investigated hydrological processesof Mediterranean temporary ponds in easternSpain through a simulation model. Sensitivityanalysis of state variables to changes on the pondparameters were developed for small and shallowMediterranean ponds in order to understand the ef-fect of pond size and shape on their hydroperiod.

This model can be of great help to manage thehydroperiod of newly made ponds or to direct therestoration of existing ponds, though it will need tobe calibrated andvalidated for eachparticular pond.

From the results of this study, there aresome predictions that should be taken into ac-count for the creation of new ponds in order tocontrol their hydroperiod:

i) Watershed area of the pond will only be im-portant for low intensity rain regimes and


for soils with very low saturated water con-tent. If the soil absorbs most of the water or,on the other hand, each rainfall episode to-tally �lls the pond, then the watershed areashould be of little importance for the pondhydroregime. Only for intermediate casesshould it be of some importance.

ii) Depth and shape are the most important pa-rameters to control the pond hydroperiod.

iii) Deeper ponds will dry more slowly (andtherefore have more days with water duringthe year and shorter drought periods) thanshallower ones, independently from theirarea and from the total amount of water. Thiswill only be the case if the water output isthrough evaporation only.

iv) Conical ponds �ll more deeply for the sameamount of rain than cylindrical ponds (samedepth and area). Therefore a conical pondshould have more days with water for thesame amount of rain, unless the pond doesget totally full in each rainfall episode. If ev-ery rainfall episode is heavy enough to to-tally �ll the pond, then there should be nodifference between the conical and cylin-drical ponds hydroperiods.

ACKNOWLEDGEMENTS

We are indebted to Vicente Sancho and IgnacioLacomba for their suggestive comments. We alsothank Juan Jimenez for his assistance along thisstudy. Acknowledgements are also given to theEnvironmental Council of Generalitat Valenciana(Spain). This work was funded by UE and GVA(LIFE05/NAT/E/000060).

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Zooplankton richness in farm ponds of Andalusia (southern Spain). Acomparison with natural wetlands

David Leon1,∗, Patricio Penalver1, Jesus Casas2, Melchor Juan2, Francisca Fuentes2, IreneGallego2 and Julia Toja1

1 Department of Ecology and Plant Biology. University of Seville. Reina Mercedes Avenue, s/n cp 41012. Seville.Spain.2 Department of Plant Biology and Ecology. University of Almeria. 04120-Almeria. Spain.2



ABSTRACT

Zooplankton richness in farm ponds of Andalusia (southern Spain). A comparison with natural wetlands

This study shows the results of an extensive survey carried out in spring 2007 on 120 farm ponds in Andalusia (South of Spain).Pond use was diverse, but the most common uses were irrigation of vast areas of land and livestock watering. Zooplanktonshowed an unexpected richness in these previously unstudied water bodies which lie on private properties. A total of 103 taxawere identi�ed (62 rotifera, 27 cladocera, 8 copepoda and 6 ostracoda). When results are compared with an extensive surveycarried out at the same time in the protected wetlands of Andalusia, we found that there are many species exclusive to boththe farm ponds and the protected wetlands. This suggests high complementary between arti�cial and natural aquatic habitats,which highlight the role of farm ponds in biodiversity conservation. Furthermore, our results showed that farm ponds withnatural substrate have a higher diversity and species richness of zooplankton than those with arti�cial substrate. Farm pondsand other farming-related ecosystems are becoming important in both ecological and management studies, because they areincreasing in landscapes all over the world. This study is part of a wider project to investigate the environmental improvementof small arti�cial water bodies in Andalusia and results will be used to promote a more useful management policy for existingand future farm ponds in this region.

Key words: Farm ponds, zooplankton, management, substrate, landscape.

RESUMEN

Riqueza del zooplancton en balsas de riego de Andaluc�a (sur de Espana). Comparacion con humedales naturales

Se presentan resultados de un muestreo extensivo de 120 balsas de riego llevado a cabo en la primavera de 2007 en Andaluc�a(Sur de Espana). Los datos de zooplancton revelan una inesperada riqueza de especies en estos cuerpos de agua, que nohab�an sido estudiados hasta la actualidad, porque muchos de ellos son de reciente creacion y estan en propiedad privada. Suuso es variado, utilizandose principalmente para el riego de vastas areas y como abrevaderos de ganado. Se han identi�cadoun total de 103 taxa (62 rot�feros, 27 cladoceros, 8 copepodos y 6 ostracodos). Cuando los resultados se compararon conun muestreo extensivo llevado a cabo en el mismo periodo en humedales naturales protegidos de Andaluc�a, se encontrarontaxones exclusivos tanto en las balsas como en los humedales, sugiriendo que estos nuevos sistemas podr�an ser reservoriospara la biodiversidad en todo tipo de paisajes agr�colas. Por otra parte, los resultados evidencian que las balsas con sustratonatural tienen una mayor diversidad y riqueza de especies de zooplancton que las balsas con sustrato arti�cial. Las balsas deriego y otros ecosistemas asociados a ambientes agr�colas estan adquiriendo importancia en ecolog�a y estudios de gestion,ya que estan proliferando en los paisajes de todo el mundo. Este estudio es parte de un proyecto de mayor envergadura acercade la capacidad ambiental de las balsas de riego de Andaluc�a. Estos resultados se usaran para promover una pol�tica degestion mas adecuada en futuras balsas de riego de la region.

Palabras clave: Balsas de riego, zooplancton, gestion, sustrato, paisaje.

154 Leon et al.

INTRODUCTION

Ponds and other wetlands have been historicallydesiccated or drained in Europe and all overthe world. Estimates of nearly 70 % have beenrecorded in some countries (Anton-Pardo et al.,2008; Cereghino et al., 2008; Lougheed &Chow-Fraiser, 2002; Oertli et al., 2002; Oertli et al.,2005; Robson & Clay, 2005; Scher et al., 2004).Since the 1970s, researchers and practitionershave been trying to reach a consensus on howto protect wetlands and several Conventions andDirectives (RAMSAR, Habitat Directive, Wa-ter Framework Directive) have been considered.However, the loss of biodiversity in these systemsstill continues. One of the causes for this con-tinuing degradation is the demand of water foragriculture. However, the requirement for water,principally in the semiarid regions of the IberianPeninsula, has given rise to an increase in thenumber of farm ponds associated with new irri-gated land (Williams et al., 2008). As such, it ispossible that these new landscape features couldsigni�cantly contribute to enhancing biodiversityin farming areas and their surroundings. Further-more, aquatic systems in agricultural landscapesare starting to be acknowledged as “pockets” ofbiodiversity (Cereghino et al., 2008; Davies etal., 2008), and we believe that farm ponds area suitable source of investigation for coloniza-tion rates, cumulative richness and trophic rela-tionships in addition to other more traditional ar-eas, such as the Donana wetlands, which has beenstudied for decades (Mar�n Cabrera & Garc�aNovo, 2005; Serrano et al., 2006).

Few studies relating to the diversity in aquaticsystems in farmed landscapes have been under-taken although there is some evidence to sug-gest that the interest of the research commu-nity has been stimulated (Davies et al., 2008;Denoel & Ficetola, 2008; Hoffman & Dod-son, 2005; Robson & Clay, 2005; Williams,1997; Williams et al., 2003; Mittelbach et al.,2001). In all cases, these researchers concludethat ponds have high species richness and, ac-cordingly, should be taken into account forstrategies of management and conservation inthose regions where they occur.

Andalusia (south of Spain) has a close relation-ship with agriculture, and a large number offarm ponds have been created in the last fewyears (CMA, 2007). A recent inventory by re-mote sensing and aerial images has identi�eda total of 16 543 ponds (Agencia Andaluza delAgua, 2006), and any of these have been sub-jected to a limnological or faunal survey (with theexception of birds surveys). The aim of this studyis to investigate the zooplankton diversity of farmponds in Andalusia, and to detect if there is anypattern of distribution, requirement of manage-ment or construction strategies in these areas topreserve biodiversity. Furthermore, a compari-son is made between farm ponds and the pro-tected natural wetlands of Andalusia to test thehypothesis that natural farm ponds are importantfor biodiversity conservation in the agriculturallandscape. Finally, in contrast to other studiesof aquatic systems of Andalusia (Alonso, 1998;Furest & Toja, 1987; Junta de Andaluc�a, 2002and 2005; Serrano et al., 2006), nothing is knownabout the zooplankton community in farm ponds.This study is part of a wider research program fo-cussing upon the environmental improvement ofsmall arti�cial water bodies in Andalusia.

STUDY AREA

Andalusia (south of Spain), has an area of about8.8 million hectares, and is located in the southof Europe (Fig. 1). This geographic situationbetween two continents and two marine areas(Mediterranean Sea and Atlantic Ocean) createsspecial climatic conditions, and offers an interest-ing opportunity to study biogeography and otherprocesses of species distribution, as other authorshave done (Alonso, 1987; Miracle, 1982). Thepercentage of steppe, for example, covers ap-proximately 10 % of the territory, and its crus-tacean diversity is more similar to Morocco andother North-African countries than to the restof Spain and Europe (Alonso, 1987; Ramdani,1988). In addition to steppe landscapes, calcare-ous mountain ranges occur in the south east ofthe region and siliceous mountain ranges can befound in the north-west with the Valley of Gua-

Zooplankton richness in farm ponds of Andalusia 155

Figure 1. Geographical location and main climatic areas of Andalusia. Localizacion geogra�ca y principales areas climaticas deAndaluc�a.

dalquivir River acting as an axis of separation be-tween them. Although the Mediterranean climateregime is paramount, there are significant climaticvariations which contribute to a considerable diver-sity of farming systems. Farm ponds, in fact, havebeen created to support different farming landuses in Andalusia; olive crops are found in theheart of the region; the ‘dehesa’ system, whichis a typical Spanish landscape with Quercus ilex,Quercus suber and scrub associated with exten-sive cattle or pig ranching is found in the northernmountains and valleys; citrus fruits and early sea-son strawberries are grown in the south west; sub-tropical fruits in the south, and protected green-house horticulture is commonplace in the east.


Andalusia covers an area of about 90 000 km2.Leibold (1999) and Dodson et al. (2000) arguethat this is a suitable scale to study pond land-

scapes (in Mittelbach et al., 2001). An extensivesurvey was carried out in spring 2007, after a se-lection of a representative number of farm pondsin the whole study area (Fig. 2). The previous se-lection by aerial images and photo-interpretationwas performed by EGMASA. This study re-vealed a total of 16 543 farm ponds. 120 of thesewere selected as a representative sub-sample forthe different geographical and land use areas(Fig. 2), and the survey was carried out by theUniversities of Seville, Granada and Almeria, tocover all the areas at once. This survey matchedup with the “Andalusia Wetlands Project”, an ex-tensive monitoring campaign of over 60 naturalwetlands, which was carried out by the “Con-sejeria de Medio Ambiente” through EGMASA.Therefore samples could be compared on a tem-poral and a spatial scale. As the monitoring andidenti�cation followed the recommendations ofour group, con�dence about the results was high.

Pond categorieswere assigned as follows:RUN,natural runoff farm pond created by damming off

156 Leon et al.

Figure 2. Approximate distribution of farm ponds and wetlands by administrative provinces compared in this study. Circles repre-sent wetlands, rectangles represent farm ponds, and those shaded are the sampled ones for the present study.Distribucion aproximadade las balsas de riego y los humedales segun provincias. Los c�rculos representan los humedales, los rectangulos las balsas y loscoloreados aquellos que se seleccionaron para el estudio intensivo.

a temporary stream; EXC, excavated farm pondwith natural substrate; WET, natural wetlands ofthe Andalusia Wetlands Project; PLA, excavatedor elevated farm pond lined with plastic; CON,excavated farm pond made of concrete. Percent-age of submerged and emergent macrophytes wasestimated and other characteristics were mea-sured and identi�ed in situ (total area of the pond,maximum depth, land use, water origin).

As most of the farm ponds were on privateland (115 of 120), a concerted effort was madeto understand the pond management decisions ofeach farmer. Pond owners were intervied in situat the beginning of the survey (as Robson & Clay,2005 did). This was a vital part of the exercisesince: the farmers are who use the farm ponds,so they should know what the project was about.Furthermore, as one of the main objectives ofthe project was to develop a pond managementhandbook with the aim of enhance biodiversityconservation, it was important to keep these vitalstakeholders fully informed.

Physico-chemical and biological sampleswere taken from every farm pond in the same wayto avoid sampling differences. Each farm pondwas divided into four or six sections depending of

the size of the water body (smaller or bigger than10 000 m2 respectively). Thereafter we select atrandom two or three sections (according to size)of the pond to make the survey. Finally, “centre”and “shore” sampling points were taken into ac-count in every selected section. In this way, themajority of habitats are sampled. Conductivity,pH and oxygen concentration were measured insitu. 10 litres as a whole were �ltered througha 40 µm net and the �lter was preserved in 4 %formaldehyde solution for the zooplankton quan-titative record. Volume from each selected sitewas equalised, and sampling was made with a6 cm diameter tube in order to integrate the wholewater column in every case. A zooplankton qual-itative sub-sample consistent in various horizon-tal hauls with a 35 µm net was made. Most of thetaxa were identi�ed to species level, in contrastto similar studies where genus was the limit ofidenti�cation (Lougheed & Chow-Fraser, 2002).Water chemistry (Table 1 and 2) was analysed bythe laboratory of Junta de Andaluc�a.

The Jaccard’s coefficient of similarity (the ratiobetween the number of common taxa and totalnumber of taxa) was used to quantify the similaritybetween paired community compositions. Pearson


Table 1. Values (average, maximum and minimum) for different limnological variables of studied farm ponds. First row indicatesprovinces (see Figure 2) where farm ponds were surveyed. They are arranged according to west-east axis. Valores (medio, maximoy m�nimo) para diferentes variables limnologicas en las balsas de riego estudiadas. La primera �la indica las provincias (Figura 2)donde se muestrearon. Estan ordenadas segun el eje oeste-este.

HU CA SE CO JA MA GR AL

pH 8.12(11-3)

8.36(9-7)

8.51(10-7)

8.62(10-7)

8.38(9-8)

8.36(9-8)

9.03(10-8)

8.45(10-8)

HCO–3

(meq/l)1.14

(4.56-.01)1.02

(2.24-.38)1.12

(3.34-.25)1.52

(3.28-.25)3.25

(6.07-.52)2.77

(4.7-.25)2.29

(5.25-.62)3.01

(4,7-.25)

C(mS/cm)

.71(3.26-.18)

3.44(9.65-.26)

1.96(7.60-.08)

.87(3-.11)

5.66(24-.42)

1.95(4.92-.25)

.74(1.03-.56)

1.39(2.46-.23)

SS(mg/l)

1079.99(4562.38-105.3)

1254.71(3468.33-136.44)

1076.6(2958.89-47.95)

503.78(1558.64-55.01)

1791.14(4403.6-385.65)

1253.77(3075.77-153.18)

544.97(827.22-347.58)

1394.44(4658.73-116.77)

Ammonia(µµµM)

15.42(96.88-.29)

25.77(154.88-.29)

12.3(57.65-.29)

12.51(48.47-.01)

70.39(327.59-4.59)

23.34(150.59-1.76)

8.14(26.82-.29)

13.57(105.65-1.06)

Phosphate(µµµM)

2.75(14.19-.48)

1.76(9.71-.45)

2.39(16.19-.01)

7.58(34.48-.29)

1.39(3.26-.52)

4.76(29.03-.01)

12.35(25.9-.48)

12.26(77.52-.52)

Tphosphorous(µµµM)

6.3(29.97-1.58)

4.1(14.97-1.45)

12.18(78.23-1.29)

17.2(59.39-.87)

3.02(5.52-1.55)

5.33(25.32-1.45)

19.53(49.97-1.94)

24.29(113.81-1.55)

Chla(µµµ g/l)

40.87(367.31-.93)

60.91(352.6-.05)

26.43(89.2-1.5)

54.77(156.46-2.76)

5.45(14.78-.81)

6.32(21.40-.8)

37.4(94.6-1.6)

72.86(489.2-.1)

n 11 9 17 13 9 8 4 11

coefficient was used for correlations between thetotal number of zooplankton taxa (cumulativerichness) and pond size, with software SPSS11. PRIMER version 5 was used to test sim-ilarities on taxa composition between sam-ples (MDS and ANOSIM), as for analysis ofPrincipal Components in water quality. Diver-sity values are referred to Shannon index (H′).

RESULTS

A total of 120 farm ponds were visited duringspring 2007 across Andalusia (Fig. 2). Climaticvariety is high in the area and the origin of wa-ter and management of each pond is differentby regions; a summary of mainly chemical fac-tors analysed is shown in Table 1 to contrast themain characteristics between regions. The resultsare only related to 90 farm ponds. The remain-ing 30 ponds were selected in the �eld and as aresult, water chemistry was not analysed. How-ever, these ponds are close to the 11 Almeria farmponds included in the analysis (Fig. 2, Table 1)

Table 2. PCA analyses showing three �rst axis explain-ing main variance of data. First axis is related to salinity,meanwhile second and third are associated with trophic level(chlorophyll-total organic carbon and phosphorous). AnalisisPCA mostrando los tres ejes que explican mas varianza delos datos. El primero se re�ere a la salinidad, mientras queel segundo y el tercero estan asociados al grado de eutro�a(cloro�la-carbono organico total y fosforo).

Variable PC1 PC2 PC3

pH 0.005 0.265 0.044Alkalinity 0.118 0.040 0.034Chloride 0.364 0.093 −0.008Sulphate 0.341 −0.159 0.008Calcium 0.358 −0.131 0.103Magnesium 0.353 −0.124 0.103Sodium 0.353 0.114 0.017Potassium 0.277 0.365 −0.075Conductivity 0.379 0.030 0.007Total dissolved solids 0.306 −0.028 0.092Ammonia 0.074 0.227 −0.291Nitrate 0.145 −0.293 0.027Nitrite −0.015 0.074 0.420Phosphate −0.075 0.120 0.569Total phosphorus −0.078 0.080 0.605Total organic carbon 0.063 0.543 −0.047Chlorophyll −0.062 0.505 0.011

% variation 36.4 15.4 11.7

158 Leon et al.

Table 3. Types and number of farm ponds by geographic-administrative area arranged by west-east axis. Tipo y numerode balsas de riego por area administrativa, ordenado segun eleje oeste-este.

HU CA SE CO JA MA GR AL Total

EXC 1 5 3 2 1 2 1 1 16RUN 8 4 14 12 2 2 1 0 43

CON 0 0 0 0 3 5 7 21 36

PLA 3 0 0 0 6 3 2 11 25n 12 9 17 14 12 12 11 31 120

where �eld management is similar and, as a con-sequence, values are expected to be similar. Zoo-plankton, other biotic communities and physico-chemical factors were completed at all sites.

All of the ponds visited are used in farm-ing practice (irrigation or watering place), sowater conductivity was not very high; howeversome of them presented values which suggestedsigni�cant salinity (Table 1). The PCA analy-sis (Table 2) showed a �rst axis related to wa-ter salinity, suggesting that farm ponds are notsuitable habitats for salinity tolerant zooplanktonspecies, as wetlands, with higher salinity range,are. This property could be an important reasonfor the protection of these systems, because theywould complement the lack of oligohaline habi-tats occurring in Andalusia due to the progres-sive salinization which historically occur in itsnatural systems (CMA, 2007).

Types of farm ponds by area and number fallinginto each category are shown in Table 3. There isa significant tendency from west to east in relationto the type of farm pond. Natural (NAT) categories(RUN, EXC) are more common in the westernareas, meanwhile artificial (ART) ones (PLA,CON) are typical towards the east. Rainfall andtypes of farming seem tobe less important (Fig. 2).

A total of 64 rotifer and 39 crustacean taxawere identi�ed in farm ponds as a whole. Thisnumber is similar to others studies (Fahd et al.,2000; Leon et al., 2004, unpublished; Lougheed& Chow-Fraser, 2002; Miracle et al., 1995; Ser-rano et al., 2005; Serrano & Fahd, 2005). Whencomparing average values of cumulative rich-ness (Table 4), it is observable that naturalizedfarm pond types (RUN, EXC) present a ma-jor number of taxa than arti�cial ones (CON,

Table 4. Average values of species richness in 120 farm pondsrelated to taxROT (taxa of rotifers), taxCRU (taxa of crus-taceans), taxTOT (taxa total), and DIV (Diversity H′). Valoresmedios de riqueza de especies en 120 balsas de riego relativos ataxROT (taxones de rot�feros), taxCRU (taxones de crustaceos),taxTOT (taxones totales) y DIV (Diversidad H′).

RUN EXC PLA CON

taxaROT 4.65 3.73 2.13 3.51taxaCRU 3.26 3.47 2.18 2.82taxaTOT 8.00 7.20 4.27 2.37DIV (H′) 1.19 1.21 1.05 0.71

PLA). To test this result, non-parametric analy-sis U-MannWhitney was used. Signi�cant differ-ences ( p = 0.05) appeared between arti�cial andnatural farm ponds for taxROT(number of rotiferataxa), taxCRU (number of crustacean taxa) and div(diversity value), meanwhile these differenceswereno significant beneath any pair of the same type(NAT, natural types;ART, artificial types).

Correlations between pond size (area, m2)and zooplankton richness re�ected differencesamong types of substrate. These correlationswere high and positive when PLA and CONtypes (r2 = 0.71, 0.61, 0.57, P< 0.01) were ex-amined and no signi�cant when RUN and EXCwere compared. Therefore species-area hypoth-esis (Dodson, 1992; Fryer, 1985; MacArthur &Wilson, 1963) was only checked for arti�cialfarm ponds. Natural farm pond types did not cor-roborate this, as in other studies (Denoel & Fice-tola, 2008; Hoffman & Dodson, 2005; Oertli etal., 2002; Williams et al., 2003).

Almost 80 % of the taxa identi�ed werepresent only in 10 % of the farm ponds or less.Common species (present in more than 20 % offarm ponds) were the copepods Acanthocyclopskieferi (Chappuis, 1925), A. robustus (G. O. Sars,1893) and Copidodiaptomus numidicus (Gurney,1909); Cladocera: Daphia magna (Straus, 1820),Simocephalus vetulus (Muller, 1776), Bosminalongirostris (Muller, 1776), Daphnia galeata(G. O. Sars, 1893) and Alonella nana (Braid,1843) were present in almost 15 % of farmponds. Rotifers were represented by much morecommon species belonging to the genus Bra-chionus, Keratella, Polyarthra, Lepadella andHexarthra, which are typical taxa of water bod-ies through Iberian Peninsula (Alonso, 1996; de


Table 5. Compared results on zooplankton biodiversity be-tween wetlands (WET, n = 61) and farm ponds (FPO, n = 120).RO: number of rotifer taxa, CRU number of crustacean taxa,ROTexc and CRUexc: number of taxa of rotifers and crus-taceans respectively, exclusive of each type of ecosystem. Re-sultados comparados de la biodiversidad del zooplancton entrehumedales (WET, n = 61) y balsas de riego (FPO, n = 120).RO: numero de taxones de rot�feros, CRU numero de taxonesde crustaceos, ROTexc and CRUexc: numero de taxones derot�feros and crustaceos respectivamente, exclusivos de cadatipo de ecosistema.

ROT CRU ROTexc CRUexc TOT

WET 54 60 26 38 114FPO 62 41 36 17 103

Manuel Barrab�n, 2000). Of the farm ponds, only7 of them contained no zooplankton taxa. All ofthem were ART (CON, PLA) type.

Comparison with wetlands

Results from the farm pond study were comparedwith other contemporary surveys carried out inAndalusia by EGMASA (Junta de Andaluc�a)over 61 natural wetlands protected by regionalregulations (see �gure 2 to location). A total of114 taxa (54 rotifers, 60 crustaceans) were iden-ti�ed in this sampling, meanwhile 103 taxa werefound in farm ponds. The comparison of resultsabout the different zooplankton communitiesare presented in Table 5.

More than 50 % of taxa were identi�ed onlyin one of the wetland types (exclusive taxa).There were species exclusively found in farmponds meanwhile others appeared only in wet-lands. This result is unexpected because many ofthese water bodies are relatively close together(Fig. 2), so common species were expected to behigher. Much of the exclusive taxa identi�ed inwetlands are species with tolerance to salinity:Moina salina (Daday, 1888),Alona salina (Alonso,1995), Artemia sp., Arctodiaptomus salinus (Da-day, 1885), Epiphanes sp. In contrast, species likeMacrothrix hirsuticornis (Norman&Brady, 1867),M. laticornis (Jurine, 1820), Chydorus sphaeri-cus (Muller, 1776), Ceriodaphnia quadrangula(Muller, 1885), Dunhevedia crassa (King, 1853),typical from ponds with low salinity (Alonso,1998) were found exclusively in the farm ponds.

NAT

ART

Figure 3. MDS analysis showing a softly clustering tendencytowards type of ponds. NAT (naturalized) includes WET (wet-lands), RUN (runoff farm ponds), EXC (excavated farm ponds);ART (arti�cial) includes PLA (farm ponds lined with plas-tic) and CON (farm ponds made of concrete bottom). MDSmostrando una ligera agrupacion relativa al tipo de balsa. NAT(naturalizadas) incluye humedales (WET), balsas de escor-rent�a (RUN) y balsas excavadas con sustrato natural (EXC);ART (arti�ciales) incluye balsas de polietileno (PLA) y balsasde hormigon (CON).

MDS analysis of zooplankton richness withinthe whole water bodies, grouping them by NAT(RUN, EXC, including WET, wetlands) andART (PLA, CON), indicates a clustering ten-dency that separates the ponds with arti�cialsubstrate from the ones with natural substrate(Fig. 3). The ANOSIM test did not reveal anysigni�cant difference in zooplankton composi-tion between groups even among geographicareas (see Fig. 2 to location).

ANOVA one-way analysis showed no differ-ences ( p > 0.05) when taxTOT (total taxa of zoo-plankton), or diversity value (div) between WET,RUN and EXC were examined. Moreover, T-Student reaf�rmed similarities in species richnessand/or diversity between any NAT type (RUN,EXC or WET) and differences among any NATtype and any ART type (CON, PLA), (Table 6).

Table 6. p-values from T-Student analyses between types offarm ponds and wetlands for species richness and/or diver-sity. p-valores del T-Student entre tipos de balsas de riego yhumedales para la riqueza de especies y/o la diversidad.

WET RUN EXC PLA CON

WET .351 .530 .045 .000RUN .543 .002 .000EXC .058 .002PLA .355CON

160 Leon et al.

DISCUSSION

Although the number of protected water bod-ies has increased in the last few years in Spain,it seems necessary to develop an environmen-tal policy over wetlands, mainly over ponds andother small water systems. Ecological studies in-cluding: seasonal pasture wetlands (Robson &Clay, 2005), irrigation and arti�cial pools (La-comba & Sancho, 2008), gravel or clay extrac-tion pools, �sh production ponds, duck farmingreservoirs (Oertli et al., 2002), ditches (Williamset al., 2003), farm ponds (Cereghino et al., 2008),and highway storm-water detention ponds (Scheret al., 2004) have appeared in the present cen-tury as a response to this concern. Tilman et al.(2001) expected that 109 ha of natural ecosystemswill be converted to agriculture by 2050. For thisreason, it is necessary to maintain investigationson farming landscapes to assess the biodiversityof these ecosystems and to achieve the necessaryresults to improve environmentally friendly man-agement of these speci�c areas.

Our results suggest that farm ponds in An-dalusia, an area with a long history of agricul-ture, show a relatively high species richness ofzooplankton at regional scale, therefore it is ex-pected to be high in other groups of aquatic or-ganisms relatively (results in progress).

Farm ponds in Andalusia seems to increase theavailability of oligohaline habitats for zooplanktonspecies, and also for other groups, which is crucialfor conservation purposes due to the historic lossand degradation of these habitats. Farm pondshave low salinity due to their use for irrigationand other farming uses. Zooplankton communitycomposition of farm ponds is different whencompared to that of natural wetlands over the samearea at the same time. Some saline tolerant taxaappeared only in wetlands, while many freshwatertaxa were identified just in farm ponds. In naturalwetlands, low salinity taxa have been found oversandy substrate in Donana, the only complex oflagoons with low salinity remains in lowlands ofAndalusia (Arechederra et al., 2006). Therefore,farm ponds seem to be able to contribute keepingand expanding their distribution area.

This study shows that natural farm ponds arericher in zooplankton species than arti�cial ones,as Scher et al. (2004) detected in their study.Statistical analyses over zooplankton richness re-vealed signi�cant differences between some ofarti�cial substrates and some of natural ones,meanwhile these differences were no signi�cantbeneath any pair of the same type (neither ARTtypes, nor NAT types). Values of species richnesswere therefore higher in natural types. Moreover,statistical analyses showed no differences in zoo-plankton species richness and diversity betweennatural farm ponds and wetlands, but differenceswere signi�cant when compared to arti�cial farmponds. In agreement with Boavida (1999), theseresults support the idea that substrate is one ofthe most important factors to consider for wet-land characterization. Natural substrate gives riseto the implementation of submerged plants, andtherefore to the appearance of more habitats, somore species can colonize it. Arti�cial substrates(plastic, concrete), make it dif�cult for plants totake root and, furthermore, such ponds are fre-quently drained, as detected in the farmers inter-views. As such, the development of habitat struc-tural complexity is more complicated. The resultsdemonstrating the absence of species in 7 arti�-cial farm ponds could be due to the subterraneanorigin of water or maybe to the extended use ofbiocides in that area (south west of Andalusia).Further research into the colonisation rates of thispond type, with and without the use of biocides,needs to be undertaken.

Relationship between area and species rich-ness was only proved for arti�cial ponds. Cor-relations were not signi�cant for natural types.This matches up with other similar studies, sug-gesting that size is not the main factor whendesigning management policies to preserve bio-diversity in aquatic systems at least for small-sized organisms. There are an increasing num-ber of studies that reveal the importance ofsmall water bodies as ’pockets’ of biodiversity, incontrast to other larger systems.

In conclusion, farm ponds should be takeninto account for strategies of biodiversity con-servation in Andalusia. Therefore, the creation


of new ponds with natural substrate and the pro-motion of environmentally friendly managementpractices is very important to increase biodiver-sity. We hope these results will encourage the An-dalusia government to improve the future manage-ment of natural ponds in the agricultural landscape.

ACKNOWLEDGEMENTS

We are grateful to Agencia Andaluza Del Agua,EGMASA and Consejer�a de Medio Ambientefor funding and supporting this study. Thanks toMar�a Gabriela Cano and Mar�a Jose Fernandezfor their help without, of course, forgetting to allthe pond owners for their patience and help in allwe needed. Finally, thanks to Sergio Segura, andMar�a Fernandez-Garc�a for their comments andcorrections over the text.

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Chlorophyll a and physical-chemical features of small water bodies asindicators of land use in the Wielkopolska region (Western Poland)

Natalia Kuczynska-Kippen & Tomasz Joniak∗

Adam Mickiewicz University of Poznan, Faculty of Biology, Department of Water Protection, Umultowska str.89, 61-614 Poznan, Poland2



ABSTRACT

Chlorophyll a and physical-chemical features of small water bodies as indicators of land use in theWielkopolska region(Western Poland)

The present paper analyzes the impact of differentiated land uses in the catchment area (pastoreo, forest and urban) on changesin phytoplankton biomass of open water in small water bodies located in the central part of the Wielkopolska region (westernPoland). Anthropogenic pressure in the pond surroundings ranged from almost negligible in the forested areas to very strongin the urban areas which were subject to the impact of the large city agglomeration. The examination of chlorophyll a andthe physical-chemical features of water were carried out over one week in July 2006. The water of the investigated pondshad a characteristically neutral to alkaline pH and moderate mineralization. Urban ponds exhibited the higher chlorophyllconcentrations and pH values. Ponds in the pastoral landscape were characterized by high concentrations of phosphorusdue to livestock in�uence. Some ponds in the pastoral area presented also high nitrate concentrations indicating agriculturalin�uence. A speci�c feature of mid-forest ponds was a relatively lower concentration of phosphate in the water, but they hada high concentration of DOM, both factors were probably responsible for the maintenance of a low biomass of algae.

Key words: Ponds, anthropogenic pressure, chlorophyll a, water chemistry, DOM.

RESUMEN

Cloro�la a y caracter�ticas f�sicas y qu�micas de pequenas masas de agua como indicadoras de los usos del suelo en laregion de Wielkopolska (Polonia occidental)

El presente art�culo analiza el impacto de los usos del suelo en la cuenca de captacion (pastoral, forestal y urbano en loscambios de la biomasa �toplanctonica de aguas abiertas en charcas ubicadas en la parte central de la region de Wielkopolska(Polonia occidental). La presion antropogenica en el entorno de las charcas fue de casi negligible en las zonas de bosque amuy intensa en las areas urbanas que estaban sujetas al impacto de una gran aglomeracion metropolitana. La determinacionde la cloro�la a y de las caracter�sticas f�sico-qu�micas del agua se realizo durante una semana en julio de 2006. El agua delas charcas investigadas ten�a un pH de neutro a alcalino y una mineralizacion moderada. Las charcas urbanas presentaronlos valores mas altos de cloro�la a y de pH. Las charcas del area pastoral se distinguieron por las altas concentraciones defosforo, debido a la in�uencia del ganado y algunas de ellas presentaban altos valores de nitratos, indicando tambien unain�uencia agr�cola. Las charcas de la zona forestal se caracterizaron por una relativamente baja concentracion de fosfato enel agua, pero con valores altos de DOM, ambos factores contribuyeron al mantenimiento de una biomasa baja de �toplancton.

Palabras clave: Charcas, presion antropogenica, cloro�la a, qu�mica de las aguas, materia organica disuelta (DOM).

164 Kuczynska-Kippen & Joniak

INTRODUCTION

The anthropogenic transformation of the catch-ment area may accelerate the nutrient enrichmentof waters, and hence it creates concern, partic-ularly, in degraded areas within urban and pas-toral landscapes. This is particularly relevant inthe case of small water bodies, which as smalland shallow ecosystems are particularly prone tosudden changes of the water quality. Althoughlarge bodies of water are objects of permanentmonitoring, in the case of small water bodiessuch examinations are often made randomly (Jo-niak et al., 2006). Interdisplinary examinationsincluding the abiotic features and biotic struc-ture of small water bodies have been carried outin Poland in recent years (Paczuska et al., 2002,Kuczynska-Kippen, 2009), and one of the mostimportant conclusions has been to indicate thevital role of anthropogenic degradation of thelandscape on the functioning of such ecosystems.At the same time considerable restrictions werefound regarding the possibility of usage of commonsystems of water trophy classi�cation of smallwater bodies were found (Joniak et al., 2009).

Small water bodies create speci�c microe-cosystems with a visible and dynamic relation-ship between abiotic features of the environmentand hydrobionts, especially algae (Prezelin et al.,1991). One of the methods for the estimation ofthe growth and development of the phytoplank-ton community is to perform an analysis of pho-tosynthetic pigments, even though the content ofchlorophyll in the cells changes with the avail-ability of light (Wetzel, 2001) and thus with depthand trophic gradient (Kasprzak et al., 2008).The aim of this study was to �nd differencesin the phytoplankton biomass and the physical-chemical features of the water in small waterbodies according to different types of landscape:forest, pastoral and urban.


According to the character of the landscape andland uses, the following types of water bodieswere distinguished: typical mid-forest (group I),

natural in an agricultural area (group II) andstrongly antropogenically modi�ed in the urbanlandscape (group III). The area of group I wascharacterised by a high degree of naturality, wi-thout traces of tree cutting or mechanical degra-dation of duff. In the group of the agriculturalarea there were intensively fertilised �elds withroot and cereal crops, as well as meadows for cat-tle pasturing. A feature characteristic of the urbanareas was the strong degradation of the groundsurface caused by mechanical levelling withheavy implements which lead to fallow lands.

The examination was carried out (once foreach pond) during one week in July 2006 on 15small water bodies, that had areas between 0.5and 5 ha and were located in the central part ofthe Wielkopolska Lakeland. Most of the pondswere very shallow (< 1.0 m), with the exceptionof three ponds (max. depth 1.5 m). Field mea-surements: temperature, dissolved oxygen (DO),electric conductivity (EC), pH, transparency withSecchi disc (SDV) and water samples for chemi-cal analysis (in triplicate) were taken in the deep-est part of the open water area (15 ponds, n = 45)and at the same time of the day to avoid diur-nal variation (8-10 am). Chlorophyll a was deter-mined after extraction in acetone. Dissolved or-

0 20 40 60 80 100

Dissimilarity (%)

P4P3P5P2P1U1U5U4U3U2F3F4F5F2F1

Figure 1. Tree diagram of pond groups (F – forest, P –pastoral, U – urban) resulting from the cluster analysis withphysical-chemical variables (complete linkage method withManhattan distance). Dendrograma de los grupos de charcas(F – forestal, P – pastoral, U – urbano) resultante del analisisde agrupamiento con las variables f�sicas y qu�micas (metodode enlace completo con la distancia de Manhattan).

Environmental features of small water bodies as indicators of land uses 165

Table 1. The physical-chemical water features (mean ± SD) of the researched ponds of different types of landscape: forest (I),pastoral (II) and urban (III). Caracter�sticas f�sico-qu�micas del agua (media ± SD) de las charcas investigadas en los distintos tipospaisaj�sticos: forestal (I), pastoral (II) y urbano (III).

Group of ponds SDV m DOM m−1 EC µS/cm−1 pH Oxygen mg l−1 TP µg P l−1 TRP µg P l−1 NO3 µg l−1 NH4 µg l−1

I 0.5±0.3 9.4±5.4 567±248 7.1±0.2 9.1±4.8 62±28 20±26 578±400 1720±460II 0.6±0.6 9.6±8.2 834±440 8.1±0.7 7.7±3.9 336±302 209±184 1970±740 1207±870III 0.8±0.5 3.1±2.0 677±407 9.0±0.5 10.2±2.9 97±64 42±61 1050±860 1800±262

ganic substances (DOM) were measured on �l-trate (0.45 µm) at 254 nm with a 5 cm quartz cell.Total phosphorus (TP), total reactive phosphorus(TRP), nitrate (NO3) and ammonia (NH4) weredetermined following methods reported by Her-manowicz et al. (1999). The trophic class wasassessed according to Carlson’s (1977) classi�-cation by the use of TSITP and TSIChl.

RESULTS AND DISSCUSION

Most of studied ponds had an alkaline water pHwith the exception of mid-forest ponds, whichwere neutral on average. In the chemical com-position of the waters a great variability wasrecorded, which suggested a difference of nat-ural conditions in the surrounding environment.The ponds were well oxygenated, however, rel-atively lower oxygen concentrations were foundin the pastoral ponds. Another sign of the harm-ful in�uence of the catchment area on the qual-ity of the investigated pastoral ponds was seen intheir higher conductivities and higher concentra-tions of nitrate and TRP, comparing to the pondsof other groups. A cluster analysis indicate thatforest ponds make up a compact group closer tourban ponds, whereas pastoral ponds compose aquite distinct heterogeneous group. The chem-istry of waters of mid-forest and urban ponds hada number of common features, especially relat-ing to the concentration of total phosphorus, totalreactive phosphorus and ammonium which con-tributed to the quality distinctiveness of the wa-ters of these water bodies (Fig. 1).

The level of mineralization of waters of theexamined pondswas not higher than 1000µScm−1,and the highest values were obtained in the pas-

toral ponds. The concentration of dissolved or-ganic matter (DOM) in these ponds was alsoa high. Small water bodies located within thecity borders were characterised by a lower DOMconcentration when compared with the mid-forest and pastoral (Table 1). A feature of waterbodies situated within the agricultural-pastoralarea, and also mid-forest had similarly highvalues of this variable, indicating the high con-centrations of organic compounds such as hu-mic substances. Such a situation is typical be-cause in the untrasformed landscape small waterbodies are the biogeochemical barriers, whicheffectively restrict the free migration of min-eral and organic substances (Szpakowska &�Zyczynska-Ba�oniak, 1994).Differences in the phytoplankton biomass were

related to each group of water bodies (Fig. 2).

Type of ponds

Forest Pastoral Urban

0

20

40

60

80

Chlorophyll

a(µgl-1)

Mediana 25%-75% Min.-Max.

Figure 2. The differentiation of chlorophyll a content in thedifferent types of pond landscapes: forest (I), pastoral (II) andurban (III). Diferenciacion del contenido de cloro�la a en losdistintos tipos de charcas: forestal (I), pastoral (II) y urbano(III).


Maximum concentrations occurred in the ur-ban ponds (45±18.8 µg l−1), which indicatedfavourable conditions for algal development.However, this situation did not lead to the com-plete depletion of mineral nutrients (Table 1). Anotable result of the massive development of al-gae was the rise in water pH (mean pH of 9.0).When the concentration of inorganic carbon isvery low in eutrophic waters, a further increasein the water pH can make the inorganic carbonbecome a restricting factor for algal develop-ment (Go�dyn, 2000). In pastoral and mid-forestponds the phytoplankton biomass (averages of16.3 µg l−1 and 5.3 µg l−1 of chlorophyll a re-spectively) was considerably lower than in ur-ban ponds. One reason for the weaker develop-ment of algae in the pastoral water bodies mighthave been the result of the in�ow of toxic sub-stances during the vegetation period that camefrom the chemical compounds used for crop pro-tection (Joniak, 2009), such as defoliants in liq-uid form, which can result in the physiologi-cal decomposition of chlorophyll (Szpakowska &�Zyczynska-Ba�oniak, 1994).The concentration of phosphates in particular

groups of ponds were considerably differentiated(Table 1). Application of the quotient TRP/TPshowed a large disproportion of the contributionof phosphates in the total phosphorus for eachtype of pond. Comparably low values of TRP/TPin the mid-forest and urban ponds (34 % and31 % respectively) re�ected a depletion of phos-phorus sources which, however, occurred in sur-plus in the pastoral ponds (62 %).

In order to �nd out the relationships amongthe variables characterising the physical-chemi-cal features of water within each group of ponds,these variables were analysed using PCA analy-sis. In each group of ponds the �rst three princi-pal components explained over 90 % of the ob-served variation, where about half was explainedby the �rst component (Fig. 3). This axis seemsto be related with trophic level in the three groupsof ponds. In mid-forest ponds this �rst compo-nent accounted for the variability of the mineralcontents in the waters and their dystrophic char-acter. Figure 3 shows that in this group of ponds,pH is much related to conductivity and that these

SDV

EC

DOM

pH

Oxygen

TRP

TPNH4

NO3

-1 0 1

Factor 1: 50.89%

-1

0

1

Factor2:23.73%

SDV

EC

DOM

pH

Oxygen

TRP

TPNH4

NO3

I

SDV

DOM

pH

Oxygen

EC

TRPTP

NH4 NO3

-1 0 1

Factor 1: 43.03%

-1

0

1Factor2:25.66%

SDV

DOM

pH

Oxygen

EC

TRPTP

NH4 NO3

II

SDV

DOM

pH

Oxygen

EC

TRP

TPNH4

NO3

-1 0 1

Factor 1: 47.71%

-1

0

1

Factor2:29.88%

SDV

DOM

pH

Oxygen

EC

TRP

TPNH4

NO3III

Figure 3. PCA analysis of physical and chemical variables ofthe water in each of the different groups of ponds, accordingto land uses: forest (I), pastoral (II) and urban (III). Analisis decomponentes principales de las variables f�sicas y qu�micas delagua en cada uno de distintos grupos de charcas segun los usosdel suelo: forestal (I), pastoreo (II) y urbano (III).


two variables are inversely related to DOM andammonia, closely placed together. This indicatethat principal component 1 accounts for a gra-dient between dystrophic ponds with an impor-tant dependence of allochthonous organic matterversus ponds with higher mineral contents andpH, the just mentioned variables go with phos-phorous since less dystrophic ponds are a possi-bly more productive. In pastoral mid-�eld pondsthe �rst component separates ponds with highnitrates from those with high DOM and phospho-rous, so this component accounts for the variabil-ity of ponds with a higher in�uence of agricul-tural �elds versus those with higher in�uence oflivestock impact. In pastoral ponds SDV had ahigher signi�cance, and a higher transparency ofthe water goes together with higher mineral con-tents, pH and nitrates, indicating that ponds withthese features had a higher in�uence from agri-cultural �elds. On the other hand, phosphorouswas positioned in the DOM-ammonium side in-dicating a higher load of organic matter possiblyrelated with stronger cattle impact, indicating ahigher trophic level. A very different situation,from the other two groups of ponds, occurs inurban ponds where autogenic production domi-nates, DOM has a very low correlation with com-ponent 1 and it is not related with ammonia, butit is related to productivity indicated by the to-tal phosphorus. In the ponds of this group pro-ductivity is determined mainly by phytoplank-ton growth, this is indicated by their higherchlorophyll content. The high pH that some ofthese ponds may reach (pH ≥9) induces deple-tion of inorganic carbon in the form of CO2 andfurther metabolic activity with the use HCO−3 willlead to different biological effects that in�uencethe major sources of variation in these waters(Wetzel, 2001). The second component is moredif�cult to interpret but may be related to someredox processes since oxygen shows very highloadings in the negative side of the axis 2 in allcases, but variables with high positive loadingsare different depending on pond types, indicat-ing dissimilarity of metabolism and functioningbetween these three groups of ponds.

The trophic conditions of the studied pondsin various types of landscape con�rms the much

higher supply of the biogenic compounds in themid-�eld water bodies, where the average valuesof TSITP amounted to 82, overgrowing the bor-ders of hypertrophic conditions. In the remain-ing types of ponds this index accounted for eu-trophy. The increase of the eutrophic processesis not a rule in the case of small water bodies,however, it is often accelerated by the in�ow ofthe biogenic substances from the catchment areaand by covering the pond bottom with organicsediments (Hongve, 1999). Signi�cantly higherconcentrations of chlorophyll in the urban pondsrepresented the highest values of TSIChl (average67), while in the pastoral and mid-forest pondsthey were lower (57 and 44 respectively). An in-teresting feature was connected with the equallevel of the TSITP and TSIChl indexes in the ur-ban ponds, in comparison with the higher val-ues of phosphorus index TSITP in the remainingtypes of ponds. Statistical analysis revealed a lackof signi�cant relationships between chlorophylland phosphorus as well as between water trans-parency and chlorophyll. According to Fairchildet al. (2005) this phenomenon indicates the factthat the trophic conditions of small water bod-ies are controlled by different parameters thanthose occurring in lakes. In small pond relation-ships with its catchment area and land uses arehigher and much of the phosphorous may be de-tritic originating from benthic–pelagic couplingand from in�ows of allochthonous organic mat-ter. Moreover the very frequent mixing of thewaters into the bottom with the resuspension ofsediments and the turn-over of the surplus of bio-genic substances accumulated in sediments intothe water column (Sondergaard et al., 2003).

Nitrogen was mainly represented by nitratesin the pastoral ponds, and by ammonium in mid-forest and urban ponds (Table 1). These differ-ences re�ected the level of landscape transforma-tion and the land use type in the catchment area.In the case of arable landscapes, the use of ar-ti�cial fertilisers is decisive in the compositionof nitrogen compounds leaching to the water ofthe ponds (Joniak et al., 2006). A dominance ofponds representing a dominance of NO−3 ions in-dicates that the surface and underground �ow ofwaters from soils was a feature responsible for


the water chemistry. A different situation existsin the case of forest soils, where the drainage ofammonium is considerably higher compared tonitrates (Klimaszyk et al., 2003).

CONCLUSIONS

1. The research con�rmed that the waters ofthe ponds were a reservoir of inorganic com-pounds, as well as of dissolved organic mat-ter. The urban and pastoral water bodies,compared with mid-forest ponds, repre-sented conditions of considerably highermineral salts and nutrients, which was re-�ected in the values of electric conductivityand concentrations of phosphorus andnitrates.

2. Urban ponds, where anthropogenic pressurewas strongest, favoured phytoplankton de-velopment (higher concentration of chloro-phyll a) compared to ponds located withinthe forest and pastoral catchment areas. Pas-toral mid-�eld ponds showed a variabilitydepending whether surrounding land useswere agricultural �elds or livestock. On theother hand mid-forest ponds could have moreor less strong dystrophic characteristics.

ACKNOWLEDGMENTS

This research work was �nanced by the PolishState Committee for Scienti�c Research in 2005-2009 as research project 2P06S 00829.

REFERENCES

CARLSON, R. E. 1977. A trophic state index forlakes. Limnol. Oceanogr., 22: 361-369.

FAIRCHILD, G. W., J. N. ANDERSON, & D. J.VELINSKY. 2005. The trophic state ‘chain of rela-tionship’ in ponds: does size matter? Hydrobiolo-gia, 539: 35-46.

GO�DYN, R. 2000. Changes in biological and phy-sico-chemical parameters of river water qualityas a result of its damming in preliminary lowland

reservoirs. AMU Press, Poznan. 186 pp.

HERMANOWICZ, W., J. DOJLIDO, W. DO�ZANS-KA, B. KOZIOROWSKI, & J. ZERBE. 1999. Thephysical-chemical analyses of water and wastewa-ter. Arkady Press, Warszawa. 556 pp.

HONGVE, D. 1999. Production of dissolved organiccarbon in forested catchments. J. Hydrol., 224: 91-99.

JONIAK, T. 2009. Hydrochemical characteristics ofwaters and an outline of the chemism of sedimentsof small water bodies in the pastoral and forestlandscape. In: Functioning of plankton communi-ties in habitat differentiated small water bodiesof the Wielkopolska area. N. Kuczynska-Kippen(ed.): 33-59. Bonami Press, Poznan.

JONIAK, T., N. KUCZYNSKA-KIPPEN, & B. NA-GENGAST. 2006. The chemistry of waters ofsmall water bodies in the agricultural landscapeof the western Wielkopolska region. TEKA Kom.Ochr. Kszt. Srod. Przyr., 3: 60-65.

JONIAK, T., B. NAGENGAST, & N. KUCZYNS-KA-KIPPEN. 2009. Can popular systems of tro-phic classi�cation be used for small water bodies?Ocean. Hydrobiol. Studies., 38(4): 145-151.

KASPRZAK, P., J. PADISAK, R. KOSCHEL, R.KRIENITZ, & R. GERVAIS. 2008. Chlorophyll aconcentration across of trophic gradient of lakes:An estimator of phytoplankton biomass? Limno-logica, 38: 327-338.

KLIMASZYK, P., M. KRASKA, R. PIOTROWICZ,& T. JONIAK. 2001. Functioning of small waterbodies of the Wielkopolska National Park (WestPoland). Verh. Internat. Verein. Limnol., 28: 1735-1738.

KUCZYNSKA-KIPPEN, N. 2009. Functioning ofplankton communities in habitat differentiatedsmall water bodies of the Wielkopolska area.Bonami Press, Poznan. 502 pp.

PACZUSKA, B., R. PACZUSKI, & E. KRASICKA-KORCZYNSKA. 2002. Mid-�eld and mid-forestreservoirs at the edge of the Wysoczyzna Swiecka(Pojezierze Krajenskie). Micro�ora, macrophytesand environment. ATR Press, Bydgoszcz. 92 pp.

PREZELIN, B. B., M. M. TILZER, O. SCHO-FIELD, & C. HAESE. 1991. The control of theproduction processes of phytoplankton by thephysical structure of the aquatic environment withspecial reference to its optical properties. AquaticSci., 53, 2/3: 135-186.


SONDERGAARD, M., J. P. JENSEN, & E. JEPPE-SEN. 2003. Role of sediment and internal load-ing of phosphorus in shallow lakes.Hydrobiologia,506-509: 135-145.

SZPAKOWSKA, B. & I. �Zyczynska-Ba�oniak. 1994.

The role of biogeochemical barriers in water mi-gration of humic substances. Pol. J. Env. Stud., 3,2: 35-41.

WETZEL, R. G. 2001. Limnology. W. B. SaundersCo., Philadelphia. 1006 pp.


The body size distribution of Filinia longiseta (Ehrenberg) in differenttypes of small water bodies in the Wielkoposka region

Anna Basinska, Natalia Kuczynska-Kippen∗ and Kasper Swidnicki

Department of Water Protection, Faculty of Biology, Adam Mickiewicz Univeristy, Umultowska 89,61-614 Poznan, Poland2



ABSTRACT

The body size distribution of Filinia longiseta (Ehrenberg) in different types of small water bodies in the Wielkoposkaregion

Small water bodies are often characterised by speci�c macrophyte species composition and different levels of predation.This may also have an effect on the body size and shape of rotifer specimens. The aim of the study was to determine therelation of the size of rotifer Filinia longiseta (body and appendages length), with respect to three speci�c kinds of pond(mid-forest, pastoral and anthropogenically changed) and to three kinds of hydromacrophytes (nymphaeids, elodeids andhelophytes) as well as comparatively to the open water zone. The examined water bodies also differed in �sh presence orabsence. Morphometric analysis of specimens of F. longiseta showed that both factors –the type of water body relating todifferent land-use in the catchment area as well as the microhabitat type– were signi�cant predictors, in�uencing their bodysize and spine length. Filinia longiseta specimens were signi�cantly smaller in ponds situated within the pastoral catchmentarea. The largest specimens were found among stands of nymphaeids, while the smallest were found within the open waterzone, which may indicate both the ecological requirements of this species as well as the marked in�uence of �sh in theunvegetated area.

Key words: Body size, Filinia longiseta, rotifers, ponds, macrophytes.

RESUMEN

Distribucion de tamanos de Filinia longiseta (Ehrenberg) en diferentes tipos de pequenas masas de agua en la region deWielkoposka

Las pequenas masas de agua estan caracterizadas a menudo por la composicion espec��ca de macro�tos y diferentes nivelesde depredacion. Esto puede tener efecto en el tamano y la forma de los rot�feros. El objetivo de este estudio fue determinar lasdiferencias de tamano (longitud del cuerpo y de los apendices) del rot�fero Filinia longiseta en tres tipos de charcas (forestales,de pastizales y antropizadas) y en tres tipos de vegetacion sumergida (ninfeidos, elodeidos y helo�tos) as� como tambien enaguas libres. Las charcas examinadas difer�an tambien por la presencia o no de peces. Los analisis morfometricos de losindividuos de F. longiseta han mostrado que tanto el tipo de charca, segun los usos del suelo en el area de captacion, comoel tipo de microhabitat in�uencian las longitudes del cuerpo y de los apendices. Los individuos de F. longiseta resultaronser signi�cativamente mas pequenos en las charcas situadas en las zonas de pastizales. Las poblaciones con individuos demayor tamano se encontraron en las matas de ninfeidos, mientras que en las de aguas libres se encontraba las constituidaspor individuos de menores dimensiones, lo que puede ser debido tanto a las adaptaciones de esta especie a las condicionesdel medio como a la reconocida in�uencia de los peces en las zonas desprovistas de vegetacion.

Palabras clave: Tamano corporal, Filinia longiseta, rot�feros, charcas, macro�tos.

172 Basinska et al.

INTRODUCTION

The factors which create a speci�c habitat cha-racter may also in�uence the structure of zoo-plankton communities (Burks et al., 2002; Ro-mare et al., 2003). The variation of aquaticvegetation, relating to morphology and the den-sity of a plant stand, may also lead to a high-er diversity compared to the open water zoneof both rotifer and crustaceans (Scheffer, 1998;Kuczynska-Kippen, 2007a). Moreover, the occu-rrence and size structure of rotifers can vary bet-ween different habitat types (Kuczynska-Kippen,2005). The biotic parameters such as �sh and in-vertebrate predators play an essential role in thedetermination of body size structures and abun-dance of zooplankton (Brooks & Dodson, 1965;Huchinson, 1967). Planktivorous �sh presentin lakes and ponds may have a size-selectivegrazing effect on zooplankton which leads tothe elimination of the largest specimens fromamong zooplankton communities (Irvine & Pe-rrow, 1992). Pelagic-associated species of zoo-plankton are often equipped with long spineswhich have been recognized as a defensive me-chanism which reduces predation by tactile pre-dators (Gilbert, 1999). Prey equipped with spi-nes are more dif�cult for predators to manipulatewhere mouth size may be a limiting factor (Lam-pert & Sommer, 2001; Radwan et al., 2004). Thedevelopment of this protective setae and the bodysize structure of zooplankton species can be mo-di�ed by the presence/absence of �sh. It has beenshown that �sh kairomons may also contribu-te to this process (Hanazato et al., 2001). Ho-wever, Wallace (2002) states that not all kindsof rotifer appendages function by directly inter-fering with predatory attack. The Filinia genuscontains species that possess movable, elonga-te, �exible appendages that swing, making wide,arc-like movements. After detecting disturban-ces in their surroundings produced by a predatoror large suspension feeder (daphnids) such spe-cies exhibit a series of swift jumping movementswhich help them to escape.

Biotic factors such as predation and compe-tition play an extremely signi�cant role in themaintenance of plankton community structure

(Brooks & Dodson, 1965). Not only predationbut also competition between particular zooplank-ton species may also have a decisive effect onthe structuring of the body size of particular zoo-plankton specimens (Gilbert & MacIsaac, 1989).

Small water bodies are speci�c ecosystemswhich function differently to large and deep la-kes (Oertli et al., 2002) and human activity intheir catchment area may have a much greatereffect on the functioning of the ecosystem com-pared to large water bodies (Camacho et al.,2008). Ponds are less stable and the various rolesland-use in their immediate vicinity seems to beof fundamental importance for the occupation ofboth plants and animals (Davies, 2005). The kindof land-use surrounding the water body may alsocontribute to basic parameters which are decisivefor the composition and abundance of most zoo-plankton organisms (George & Win�eld, 2002;Miller et al., 1997). The irregular processes thattake place in a temperate climate, e.g. wind mi-xing or surface �oods, will also in�uence thephysical-chemical and biological parameters ofwater, especially in the case of shallow reservoirs(Joniak et al., 2000). The above mentioned fac-tors affect the composition and abundance of ro-tifer community structure; in addition they alsocontribute to the size structure of particular roti-fer species. Filinia longiseta, which is a commonand cosmopolitan planktonic rotifer usually oc-curring in shallow lakes and variety of small wa-ter bodies (Nogrady, 1993; Radwan et al., 2004),is known to be a valuable indicator of eutrophicwaters (Karabin, 1985; Berzin�s & Pejler, 1989;Ejsmont-Karabin, 1995). Even though Filinia isan indicator of eutrophy, it has also been foundin mesotrophic lakes (Maemets, 1983). Althoughtaxonomic problems in this genus are still unre-solved (Sanoamuang, 1993), some authors dis-tinguish several forms or subspecies within thisspecies (Koste et al., 1978; Radwan et al., 2004),which according to Nogrady (1993) are separatespecies. Therefore in the present study this rotiferis described as Filinia longiseta-complex, inclu-ding its various forms. Both the occurrence andnumber of zooplankton are often modi�ed by thehabitat preference of a species, this is connectedwith overall food conditions which occur within

Filinia longiseta body size in Wielkoposka ponds 173

a particular water body (de Azavedo & Bonecker,2003). Filinia species feed well on detritus, bac-teria as well as on Chlorococcales (Koste et al.,1978; Nogrady, 1993; Radwan et al., 2004).

Therefore, the aim of this study was to deter-mine the relationship between individuals of Fi-linia longiseta (Ehrenberg) representing differentbody sizes within speci�c types of ponds (mid-forest, pastoral and anthropogenically changed)and within different habitats (open water zone aswell as within two kinds of hydromacrophytes–nymphaeids and helophytes).


This study analyzed samples collected from 31stations within 19 small water bodies locatedin the Wielkopolska region of western Poland(Table 1). At least 30 individuals of Filinia lon-giseta were measured from among ten stationsin seven water bodies. The type of land-use inthe catchment area, type of aquatic vegetation aswell as predation pressure differed among par-ticular ponds. The examined water bodies we-re classi�ed into three groups depending on the

Table 1. Characteristics of examined ponds indicating the sampled stations. Size of the ponds stated as categories: 1-very small(<0.5ha), 2-small, 3-small/medium, 4-medium, 5-big, 6-very big (5 ha). Caracter�sticas de las charcas estudiadas con indicacionde las estaciones de muestreo. Tamano de las charcas segun las siguientes categor�as: 1-muy pequena (<0.5 ha), 2 pequena, 3pequena-media, 4 media , 5 grande y 6 muy grande (5 ha).

POND NAME DATECATCHMENT

AREAPONDSIZE

PONDDEPTH (m)

FISHPRESENCE STATION

01 Batorowo 25.06.04 ANTROPOGENIC 3 0.5 ABSENT WATER *(Poznan) PHRAGMITES AUSTRALIS

02 Marcelin 22.06.04 ANTROPOGENIC 4 3.5 PRESENT PHRAGMITES AUSTRALIS *(Poznan) POLYGONUM AMPHIBIUM *

WATER *

03 Sw. Jerzy 22.06.04 ANTROPOGENIC 04 1.0 PRESENT TYPHA ANGUSTIFOLIA *(Poznan) WATER *

4 Klempicz 18.06.05 ANTROPOGENIC 2 0.6 PRESENT WATERPOTAMOGETON NATANSTYPHA ANGUSTIFOLIA

05 Owcza 20.07.05 ANTROPOGENIC 5 0.5 ABSENT CERATOPHYLLUM DEMERSUMWATER

06 Coton 23.06.06 FIELD 4 1.1 PRESENT WATER *

07 Klonowiec 27.07.06 FIELD 5 3.5 ABSENT WATER *

08 Przysieka 24.06.06 FIELD 1 1.0 PRESENT WATER *

09 Dabrowka 20.06.04 FIELD 3 0.7 PRESENT PHRAGMITES AUSTRALISPOTAMOGETON PECTINATUS

10 Paledzie 25.06.04 FIELD 4 1.5 PRESENT WATERPOTAMOGETON CRISPUS

11 Piotrowo 16.06.02 FIELD 1 1.0 PRESENT CHARA FRAGILIS

12 Tarnowo 8 12.07.06. FIELD 2 0.8 PRESENT NUPHAR LUTEUM

13 Tarnowo 21 18.06.05 FIELD 3 2.0 ABSENT WATER

14 Kraj Warty 19.06.05 FOREST 4 1.5 ABSENT WATER *

15 Gazbruchy M 10.06.04 FOREST 5 0.6 ABSENT POA ANNUAWATER

16 Gazbruchy W 10.06.04 FOREST 6 1.0 ABSENT SCHOENOPLECTUS LACUSTRISPOTAMOGETON LUCENS

WATER

17 Hindak 09.06.04 FOREST 5 0.5 ABSENT WATER

18 Mi�kowo 18.06.05 FOREST 5 1.2 ABSENT WATER

19 Obrzycko 17.06.06 FOREST 2 0.5 ABSENT WATER *

* Station where Filinia longiseta was found in representative numbers.

174 Basinska et al.

character of the surrounding area: forest, fieldand anthropogenically modified, situated in urbanplaces. Of the ponds in which Filinia longisetawas found, three were situated within the stronglyanthropogenically modified city of Poznan (pondsnumbered: 1, 2, 3), three water bodies werelocated within the pastoral catchment area (pondsnumbered: 6, 7, 8) and only one within the forestcatchment area (pond number: 14) (Table 1).

The aquatic vegetation in the ponds differed andrepresented three ecological groups: nymphaeids,elodeids and helophytes. The helophytes wererepresented by Schoenoplectus lacustris (L.),Phragmites australis (Cav.) Steud and Typha an-gustifolia (L.). Among nymphaeides three specieswere identified: Polygonum amphibium (L.), Po-tamogeton natans (L.) and Nuphar luteum (L.).The highest variety of species was recorded inthe group of submerged plants: Chara fragilis(Desv.), Ceratophyllum demersum (L.), Poa an-nua (L.), Potamogeton crispus (L.), Potamoge-ton lucens (L.) and Potamogeton pectinatus (L.).

The examinated water bodies also differedwith respect to �sh presence. Fish were presentin 8 of the 19 ponds (Table 1).

Samples were collected in the summer periodbetween 2002 and 2005 from single-species plantstands or unvegetated stands, which are called open

water stations. A plexiglass core sampler was usedto sample the macrophyte-dominated stations. Thecollected material, taken in triplicate at each site,was concentrated using a 45-µm plankton net andwas fixed immediately with 4% formalin. Thewater chemistry at particular stations included to-tal phosphorus, total nitrogen and chlorophyll a.

Filinia longiseta specimens were measured atthe longest part of the animal’s body and two spines–the lateral and also the caudal seta weremeasuredseparately in least 30 specimens in each sample.

Analysis of variance (ANOVA) with posterioriTukey test was used to identify the differences inbody size of individuals of rotifer species betweenparticular kinds of habitats, including hydroma-crophytes and the open water zone and also bet-ween particular types of water bodies (N = 303).

RESULTS

Filinia longiseta was found within seven of thenineteen water bodies and in ten of the thirty oneinvestigated stations. An abundance of this spe-cies were found in pond 1 within the open wa-ter zone (695 ind L−1± 371 SD), pond 7 withinthe open water area (899 ind L−1± 255 SD) andin pond 2 in samples taken from the Phragmi-

Table 2. Total phosphorus-TP [mg/L], total nitrogen-TN [mg/L] and chlorophyll a-Chl a [µmg/L] concentration compared withdensity [mean ind L−1], mean body length [µm] and mean seta lengths [µm] of Filinia longiseta in particular stations among differenttype of ponds. Foforo total TP [mg/L], nitrogeno total TN [mg/L] y cloro�la a Chl a [µmg/L] junto con la densidad media [ind L−1] yla longitud media del cuerpo y de los apendices [µm] de Filinia longiseta en cada una de las estaciones de muestreo en los diferentestipos de charcas.

PONDCATCHMENT

AREAFISH

PRESENCE STATION TP TN Chl a DensityBodylength

Lateralsetaelength

Caudalsetalength

01 ANTHROPOGENIC ABSENT WATER 0.280 2.837 363.6 603 173.47 354.53 177.20

02 ANTHROPOGENIC PRESENT PHRAGMITES AUSTRALIS 0.040 1.258 3.85 791 174.27 497.67 261.23POLYGONUM AMPHIBIUM 0.030 1.485 2.57 296 208.67 579.33 244.93

WATER 0.100 1.844 0.001 033 189.47 598.00 313.60

03 ANTHROPOGENIC PRESENT TYPHA ANGUSTIFOLIA 0.020 1.596 74.84 046 170.48 668.38 371.00WATER 0.070 1.188 9.41 069 229.47 891.07 456.13

06 FIELD PRESENT WATER 0.085 1.764 9.84 051 141.72 304.64 197.87

07 FIELD ABSENT WATER 0.460 3.204 — 899 150.13 384.53 243.03

08 FIELD PRESENT WATER 0.020 1.535 81.26 033 171.38 366.30 296.93

14 FOREST ABSENT WATER 0.170 1.240 48.65 029 184.80 767.67 384.53


Mean

Mean±SE

field forest anthrop150

155

160

165

170

175

180

185

190

195

200

µm

Figure 1. Filinia longiseta body length in different ty-pes of water bodies (forest-mid-forest, �eld-pastoral, anthrop-anthropogenically modi�ed). Longitud del cuerpo de Filinialongiseta en diferentes tipos de charcas (forest = forestales,�eld = de pastizales y anthrop = antropizadas).

tes australis stand (mean 791 ind L−1±211 SD).The smallest abundance of Filinia longise-ta was recorded in the open water zonein pond 6 (mean 33 ind L−1±2 SD), pond 8(mean 35 ind L−1±33 SD) and in pond 14 (mean44 ind L−1±55 SD) (Table 2).

Mean

Mean±SE

water heloph nymph165

170

175

180

185

190

195

200

205

210

215

µm

Figure 2. Filinia longiseta body length in different ecologicalhabitat types (water-open water zone, heloph-helophytes andnymph-nymphides stands). Longitud del cuerpo de Filinia lon-giseta en diferentes tipos de habitats (water = aguas libres, he-loph = helo�tos y nymph = ninfeidos).

Morphometric analyses of specimens of Fi-linia longiseta included data from various sta-tions located in seven reservoirs (pond numbers:1, 2, 3, 6, 7, 8, 14) and showed differences inthe body length value between water bodies su-rrounded by different types of catchment area,

Table 3. Results of Tukey tests, signi�cance level: * <0.05, ** <0.01, *** <0.001 and ns-not signi�cant for differences of Fi-linia longiseta body length, lateral setae length and caudal seta length among different types of ponds (forest-mid-forest, �eld-pastoral, anthrop-anthropogenically modi�ed) and among different habitats (water-open water zone, heloph-helophytes and nymph-nymphaeids stands). Resultados de las pruebas de Tukey, niveles de signi�cacion: * <0.05, ** <0.01, *** <0.001 y ns-no signi�cativopara las diferencias en las longitudes del cuerpo, de las setas laterals y de la seta caudal de Filinia longiseta entre los diferentestipos de charcas (forest-forestales, �eld-de pastizales, anthrop-antropicas) y entre los diferentes habitats: water-zona de aguas libres,heloph-helo�tos y nymph-ninfeidos).

body length

pondtype �eld forest anthrop mtype water heloph nymph�eld *** *** water ns ***forest *** ns heloph ns ***anthrop *** ns nymph *** ***

lateral setae length

pondtype �eld forest anthrop mtype water heloph nymph

�eld *** *** water *** **forest *** *** heloph *** nsanthrop *** *** nymph ** ns

caudal seta length

pondtype �eld forest anthrop mtype water heloph nymph�eld *** *** water ns ***forest *** *** heloph ns ***anthrop *** *** nymph *** ***

176 Basinska et al.

Mean

Mean±SE


350

400

450

500

550

600

650

700

750

800

µm

Mean

Mean±SE


520

540

560

580

600

µm

A B

Figure 3. Filinia longiseta lateral setae length: (A) in different types of water bodies (as in �gure 1) and (B) in various ecologicalhabitats (as in �gure 2). Longitud de las setas laterales de Filinia longiseta: (A) en diferentes tipos de masas de agua (como en la�gura 1) y en diferentes habitats ecologicos (como en la �gura 2).

irrespective of the examined station. The indi-viduals of this species were signi�cantly larger(F = 52.3876, p < 0.0001) in the anthropoge-nically alerted ponds and in the mid-forest re-servoirs, contrary to water bodies surroundedby �elds (Fig. 1, Table 3).

Comparing different types of habitat (irrespec-tive of the type of pond) signi�cantly smaller spe-ecimens of Filinia longiseta, in relation to the bodylength, were noted among helophytes and theopen water zone contrary to stations located with-

in nymphaeids, where the largest individuals we-re found (F = 15.0725, p < 0.01) (Fig. 2, Table 3).No representatives of Filinia longiseta were foundin the samples collected from among elodeids.

Morphometric analysis of lateral setae lengthsalso revealed variation in respect to different ty-pes of water body (F = 321.4887, p < 0.01),irrespective of habitat. The longest setae were re-corded from specimens collected from forest re-servoirs. The mean length values of lateral setaewere found in the anthropogenically in�uenced

Mean

Mean±SE


240

260

280

300

320

340

360

380

400

µm

Mean

Mean±SE


240

250

260

270

280

290

300

310

320

330

µm

A B

Figure 4. Filinia longiseta caudal seta length: (A) in different types of water bodies (as in �gure 1) and (B) in various ecologicalhabitats (as in �gure 2). Longitud de la seta caudal de Filinia longiseta: (A) en diferentes tipos de masas de agua (como en la �gura 1)y en diferentes habitats ecologicos (como en la �gura 2).


water bodies and signi�cantly shorter setae of Fi-linia longiseta were observed in the case of mid-�eld ponds (Fig. 3A, Table 3).

A comparison among different habitat types(irrespective of the investigated types of ponds)showed that signi�cantly shorter lateral setae ofthis rotifer species were recorded from amongthe open water contrary to the zones locatedwithin helophytes and nymphaeides (F = 8.1299,p < 0.01) (Fig. 3B, Table 3).

Biometric analysis of the length of the caudalseta of Filinia longiseta also revealed statisticallysigni�cant differences in respect to different ty-pes of water bodies (F = 57.78, p < 0.0001). Si-milar to results obtained from measuring the late-ral setae length, the longest caudal seta was foundin the samples collected from forest ponds, whi-le the shortest were obtained from the �eld waterbodies (Fig. 4A, Table 3).

Analyses of caudal seta length of this speciesinhabiting different kinds of habitats, irrespectiveof the studied types of ponds revealed signi�cantdiscrepancies (F = 7.6843, p < 0.01). The short-est caudal setae of Filinia longiseta individualswere noticed in the samples collected from nym-phaeid stands and much longer setae were no-ted in the stations located within the open waterzone and among helophytes (Fig. 4B, Table 3).

The concentration of total phosphorus, to-tal nitrogen and chlorophyll differed bet-ween the sampled stations (Table 2). The ma-ximal content of phosphorus was observedin pond 6 (TP = 1.41 mg L−1) and pond 14(TP = 1.06 mg L−1), while the minimal concen-tration was recorded from all stations withinpond 2 (TP = 0.01 to 0.02 mg L−1). Analyzingthe total nitrogen content from particular sta-tions, a different pattern of minimal and ma-ximal value distribution was observed com-pared to total phosphorus concentration. Thehighest total nitrogen concentration was foundin pond 1 (TN = 2.84 mg L−1) and pond 7(TN = 2.10 mg L−1), while the lowest was foundin the case of pond 8 (TN = 1.06 mg L−1). Thelargest differences were found between chlo-rophyll a content from among particular stationsin the examined ponds. The maximal value wasnoted in pond 1 (363.6 mg L−1), while the mini-

mal was observed in pond 2 from among the openwater zone (0.001 mg L−1). In pond 5 the concen-tration of chlorophyll was not analyzed.

DISCUSSION

The ecological requirements of Filinia longisetawere con�rmed in the present study, as the ma-jority of sampled stations where it was found inrepresentative numbers were located within theopen water zone. Also the highest abundance ofthis species was recorded from the pelagic areaof the anthropogenic pond without �sh predationpresent (pond 1). Filinia longiseta is equippedwith two long lateral setae which help the spe-cies to jump rapidly backwards when threatened.The lateral setae can be two to four times lon-ger than the body size of this species (Nogrady,1993), so a very dense stem structure of aqua-tic plants can impede the movement of this ani-mal. Therefore, in the collected material Filinialongiseta avoided elodeids, which con�rms bothits ecological requirements and the adaptations ofits morphological build to live in the open water.However, in some cases (e.g. pond 2) an oppo-site pattern of spatial distribution of Filinia indi-viduals was observed with highest densities attri-buted to littoral zone. High predation pressure inthis small water body is probably the reason forobtaining such a discrepancy. Fish presence ofteninduces horizontal migrations of numerous spe-cies of zooplankton towards aquatic plants stands(e.g. Scheffer, 1998), where effective refuge con-ditions for zooplankton can be found (Iglesias etal., 2007). Similar results were obtained by Na-rita et al. (1983) who found that in water bodieslocated within areas where land is subject to hu-man activity F. longiseta revealed higher abun-dance among macrophyte stations.

There were six mid-forest ponds included inthis study and only in one of them did Fili-nia longiseta occur in representative numbers(pond 14) and only in low densities, which cansuggest that environmental conditions of this ty-pe of water body are below optimal requirementsfor the growth and development of F. longiseta.Small mid-forest ponds are often overshaded and

178 Basinska et al.

this can lead to a lowering of the water tempe-rature. Filinia longiseta is described as warm-stenotherm species, developing most abundantcommunities at a temperature of between 23 and31 ◦C (Nogrady, 1993), so its occurrence is typi-cal for the summer period in freshwaters of thetemperate climatic zone (Duggan et al., 2001).Ejsmont-Karabin and Kuczynska-Kippen (2001),who carried out research on urban ponds loca-ted within the city of Poznan, compared seaso-nal changes in the composition and abundance ofrotifers and found that Filinia longiseta was re-corded only from samples collected during thesummer season. Moreover, long-term data fromshallow eutrophic lakes (Andrew & Fitzsimons,1992) have indicated that temperature changeshave an immediate and direct in�uence on thedensity and occurrence of rotifers, including F.longiseta. The preference of Filinia longiseta to-wards the pelagic zone and its association withwarm and unshaded water bodies was probablythe reason for the absence of this species in someof the ponds as it occurred in only seven out ofthe nineteen investigated water bodies and onlyin ten out of thirty one studied stations.

Biometric analysis of specimens of Filinialongiseta showed that both parameters includedin this study –the type of water body relating todifferent land-use as well as microhabitat type–signi�cantly in�uenced Filinia longiseta size andthe length of its setae. Individuals of this specieswere largest in ponds located within an anthro-pogenically modi�ed landscape (irrespective ofthe type of habitat). This type of water body wasalso characterized by the highest content of totalnitrogen and wide range of chlorophyll a concen-trations. Human activity in the catchment area ofa water body often in�uences the enrichment ofthe surface waters in nutrients which can positi-vely correlate with the size structure of zooplank-ton (Wang et al., 2007). This may have been areason for �nding the largest individuals of thisrotifer in anthropogenically modi�ed ponds. Fi-linia longiseta, a typical eutrophic representati-ve, which bene�t from a high biomass of phyto-plankton, can successfully occur in water bodieswhere blue-green algal blooms are present due tothe fact that it is not susceptible to bacterial toxins

( �Ceirans, 2007). The body dimensions of someindividuals in two ponds (pond 3 and pond 14)may suggest coexistence Filinia longiseta longi-seta with Filinia longiseta limnetica (Zacharias),but these species occur in different environments.Filinia longiseta limnetica is described as typicalfor large and deep lakes, so its presence in platesmall water bodies is doubtful. Moreover, lengthanalysis was conducted on preserved material,which may cause shrinking of the soft body. Thisprobably has an in�uence on the proportion bet-ween ratios lateral setae and body length becausespines are not changed by formalin. So any futu-re research as regards the morphology of F. lon-giseta should be carried out on live specimens.The smallest specimens of Filinia longiseta werefound in the mid-�eld ponds. As these ponds we-re characterised by a wide range of nutrient con-tent, as well as of chlorophyll a concentrations,it seems that food conditions may have been res-ponsible for the occurrence of the smallest indivi-duals with shorter spines here. This concurs withthe observation of Radwan et al. (2004), who sta-ted that the body size and shape of many rotiferspecimens is determined directly by food availa-bility. Filinia longiseta feeds mainly on detritus,so the relationship with chlorophyll a concentra-tion should not be taken into consideration in thisstudy. The results obtained from Devetter (1998)revealed that Filina longiseta was negatively co-rrelated with the smallest fraction of phytoplank-ton and also with predator species of Cyclops.Filinia specimens with longer spines were attri-buted to the forest ponds and also to anthropo-genically changed water bodies, while the shor-test spines were found in the mid-�eld ponds.Such a pattern of bristle length distribution maysuggest strong pressure of invertebrate predatorssince the majority of these water bodies werewithout �sh. Individuals of Filinia longiseta areconsumed willingly by representatives of cope-pods, which will often prefer this rotifer spe-cies even to Keratella cochlearis (Williamson,1987; Roche, 1990), which is believed to be themost common freshwater metazoan in the world(Lindstrom & Pejler, 1975; Koste et al., 1978)and often occurs in great numbers in a varietyof water bodies (Kuczynska-Kippen, 2007b;


Kuczynska-Kippen, 2008). Furthermore, Filinia isoften preyed on by the second-instar of Chaoborus(Moore, 1988) and also by predatory species of thelarge rotifer Asplanchna, whose presence may in-duce an increase in the length of the setae ofF. lon-giseta individuals (Garza-Mourino et al., 2005).

Comparing different types of habitat (irres-pective of the investigated type of pond) dis-crepancies were found concerning the length ofthe rotifer body, lateral setae and caudal seta.The shortest lateral setae were noticed among theopen water zone, contrary to two zones locatedwithin the aquatic plants –helophytes and nym-phaeides. This seems to be contrary to expecta-tions, as the longest bristle as an adaptation to pe-lagic life should be found in the open water area,where �sh predation is strongest during day androtifer appendages are usually longer as a mecha-nism to reduce the effectiveness of a predator’sattack (Lampert & Sommer, 2001).

ACKNOWLEDGEMENTS

This work was supported by the Polish Committeefor Scientific Research (KBN) under grant No.2P06S 00829. The authors would also like to thankB. Nagengast for identification of macrophytespecies in examined water bodies andM. Cichockaformeasuring zooplankton specimens.

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• Revistas:RUEDA, F. J., E. MORENO-OSTOS & J. ARMENGOL. 2006. The

residence time of river water in reservoirs. Ecological Modelling, 191: 260-275.

GRACA M. A. S. & C. CANHOTO. Leaf litter processing in low orderstreams. Limnetica, 25(1-2): 1-10.

RECHE, I., E. PULIDO-VILLENA, R. MORALES-BAQUERO & E. O.CASAMAYOR. 2005. Does ecosystem size determine aquatic bacterial rich-ness? Ecology, 86: 1715-1722.

• Libro:KALFF, J. 2002. Limnology. Prentice Hall. NJ. USA. 592 pp.• Cap�tulo de libro:IMBODEN, D. M. 1998. The in�uence of Biogeochemical Processes on

the Physics of Lakes. In: Physical Processes in Lakes and Oceans. J. Iberger(ed.): 591-612. American Geophysical Union. Washington. USA.

• Congresos:GEORGE, D. G. 2006. Using airborne remote sensing to study the mixing

characteristics of lakes ans reservoirs.10th European Workshop on PhysicalProcesses in Natural Waters. June 26-28, 2006. Granada, Spain: 2001-207.

• Informes:DOLZ, J. & E. VELASCO. 1990. Analisis cualitativo de la hidrolog�a

super�cial de las cuencas vertientes a la marisma del Parque Nacional deDonana (Informe Tecnico). Universidad Politecnica de Cataluna. 152 pp.

• Tesis y Maestrias:MORENO-OSTOS, E. 2004. Spatial dynamics of phytoplankton in El

Gergal reservoir (Seville, Spain). Ph.D. Thesis. University of Granada. 354 pp.THOMPSON, K. L. 2000. Winter mixing dynamics and deep mixing in

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waters. Its scope includes ecology of rivers, lakes, reservoirs, lagoons andwetlands, biogeochemistry, paleolimnology, development of new methods,taxonomy, biogeography, and all aspects of theoretical and applied continentalaquatic ecology, like management and conservation, impact assessment,ecotoxicology and pollution. Limnetica will accept for publication scienti�cpapers presenting advances in knowledge or technological development, aswell as papers derived from new practical approaches on the topics coveredby the journal.

Manuscript presentationManuscripts must be submitted by e-mail to the journal Editor (jarmen-

[email protected]). Manuscripts also can be sent to the Editor by regular mail (orig-inal plus two hard copies and one digital copy. The digital copy must include a�le with text, tables and �gures following the present instructions, made withPC-compatible text-edition software (MSWord, Wordperfect, etc.).

Both hard and digital copies will be typed at double space on A-4 sheets.Papers can be written in Spanish or English, and must not exceed 6000 wordsof text nor 25 printed pages (�gures and tables included). Exceptionally, andafter consulting the Editor, longer manuscripts can be published for generalreviews, systematics of broad taxonomic groups, or regional comparativestudies of one kind of aquatic ecosystems. Papers that do not follow the presentinstructions will be rejected.

Limnetica’s Editorial Board will decide whether to publish or not thereceived manuscripts, and will tell their decision to the authors. Prior topublication, authors will get galley proofs to be corrected. When the paperhas been published, the leading author will get a copy in pdf format.

Manuscript structureFor manuscripts in Spanish, words in UPPER CASE will be accentuated

when convenient, both in the title and section headings (INTRODUCCION,etc.).

The �rst page must include:• Title in upper case.• List of authors detailing the corresponding author, whose e-mail address• must be shown.• Complete postal address of authors.• Running title.The second page will include Abstract and key words, both in English and

Spanish. Abstracts must start with the title and not exceed 400 words.Following pages must be structured in sections following the scienti�c

style. Section headings and text will have no left indent. Upper case words inSpanish will be accentuated.

Sections and subsections will not be numbered, and must adjust to thefollowing format:

Main section.- Bold, upper case (INTRODUCTION).2nd-level section.- Bold, lower case.3rd-level section.- Italics.4th-level section.- Plain text, underlined.Lower-level sections.- They will go numbered (1), (1.1), (1.1.1), etc.Tables are one of the most costly parts, both in terms of time and money;

therefore, they must be drawn as compact as possible. Tables can be 1-column(8 cm) or 2-column (16 cm) wide, and their length cannot exceed 25 cm. Theywill be included at the end of the manuscript and numbered in Arabic numbers.In the text they will be written in complete form (e.g., as can be seen in Table6. . . , or Data (Table 6) show that. . . ), never in abbreviated form (neither Tab.6 nor tab. 6). Table captions will be written in both English and Spanish, andwill be included in the text in the same section than Figure legends. No verticallines can be drawn in tables, and column headings must be short. No table willbe published that shows information presented in �gures.

Figures will have Arabic numbers, and legends will go below, both inEnglish and Spanish. Figures can �t three box-sizes: 8 cm, 12.5 cm, or 16 cm.

Authors must make sure that font size and line thickness can be easily readafter reduction, otherwise �gures will be rejected.

Figure legends and table captions will go in a page after Literature Citedand before Tables and Figures.

Figure calls must be made in complete, lower case form when in the text(e.g., Location of sampling sites is shown in �gure 1), in abbreviated, uppercase when going in a parenthesis and not directly related to the text [e.g.,Samples were taken monthly at �ve sites along the river (Fig. 1)]. The Editorwill accept to publish colour �gures and photographs only exceptionally andwhen explicitly requested.

Units must be expressed preferably following the International System(I.S.), with abbreviated symbols when preceded by numeric expressions.Values combining two units must be expressed with the correspondingarithmetic sign, like m/s, mol/m3, ind/l, but when there are more than twounits exponentials must be used, like in mgC m−2 h−1, µmol m−2 s−1.

Decimal numbers will be expressed with a dot (4.36), thousands with 4digits, with no blank space or symbols (4392), and �gures over ten thousandwill have blank space markings (13 723 or 132 437). Whenever possible thescienti�c notation will be used, with the smallest possible number of decimals(13.7·103, 13.2·104).

BIBLIOGRAPHY will be after the text, in alphabetic order, chronologi-cally for each author, and adhere to the following style:

• Journals:RUEDA, F. J., E. MORENO-OSTOS & J. ARMENGOL. 2006. The

residence time of river water in reservoirs. Ecological Modelling, 191: 260-275.

GRACAM. A. S. & CRISTINA CANHOTO. Leaf litter processing in loworder streams. Limnetica, 25(1-2): 1-10.

RECHE, I., E. PULIDO-VILLENA, R. MORALES-BAQUERO & E. O.CASAMAYOR. 2005. Does ecosystem size determine aquatic bacterial rich-ness? Ecology, 86: 1715-1722.

• Books:KALFF, J. 2002. Limnology. Prentice Hall. NJ. USA. 592 pp.• Book chapters:IMBODEN, D. M. 1998. The in�uence of Biogeochemical Processes on

the Physics of Lakes. In: Physical Processes in Lakes and Oceans. J. Iberger(ed.): 591-612. American Geophysical Union. Washington. USA.

CASTRO, M., J. MARTIN-VIDE & S. ALONSO. 2005. El clima deEspana: pasado, presente y escenarios de clima para el siglo XXI. In:Evaluacion preliminar de los impactos en Espana por efecto del CambioClimatico. J. M. Moreno Rodr�guez (ed.): 113-146. Ministerio de MedioAmbiente.

• Conferences:GEORGE, D. G. 2006. Using airborne remote sensing to study the mixing

characteristics of lakes ans reservoirs.10th European Workshop on PhysicalProcesses in Natural Waters. June 26-28, 2006. Granada, Spain: 2001-207.

• Reports:DOLZ, J. & E. VELASCO. 1990. Analisis cualitativo de la hidrolog�a

super�cial de las cuencas vertientes a la marisma del Parque Nacional deDonana (Informe Tecnico). Universidad Politecnica de Cataluna. 152 pp.

• PhD and Master Dissertations:MORENO-OSTOS, E. 2004. Spatial dynamics of phytoplankton in El

Gergal reservoir (Seville, Spain). Ph.D. Thesis. University of Granada.354 pp.

THOMPSON, K. L. 2000. Winter mixing dynamics and deep mixing inLake Tahoe. Master’s Thesis, University of California, Davis. 125 pp.

The Bibliography will only contain papers cited in the text, where theymust go in lower case (Margalef, 1975; Wetzel & Likens, 1991; Riera et al.,1992). In no case will unpublished (e.g., in prep., submitted) papers be cited,unless they are accepted for publication (in press). References to works hardto get (reports, conference abstracts, etc.) must be limited to the minimumpossible.

LIMNETICA Vol. 29 (1), 2010

INDICE

001 MARIA R. MIRACLE, BEAT OERTLI, REGIS CEREGHINO AND ANDREW HULL. Preface: conservation ofeuropean ponds-current knowledge and future needs

009 JOHN A. DOWNING. Emerging global role of small lakes and ponds: little things mean a lot025 LUC BRENDONCK, MERLIJN JOCQUE, ANN HULSMANS AND BRAM VANSCHOENWINKEL. Pools ‘on the

rocks’: freshwater rock pools as model system in ecological and evolutionary research

041 CARMEN DIAZ-PANIAGUA, ROCIO FERNANDEZ-ZAMUDIO, MARGARITA FLORENCIO, PABLOGARCIA-MURILLO, CAROLA GOMEZ-RODRIGUEZ, ALEXANDRE PORTHEAULT, LAURA SERRANO AND

PATRICIA SILJESTROM. Temporay ponds from Donana National Park: a system of natural habitats for thepreservation of aquatic �ora and fauna

059 MARGARITA FERNANDEZ-ALAEZ AND CAMINO FERNANDEZ-ALAEZ. Effects of the intense summerdesiccation and the autumn �lling on the water chemistry in some Mediterranean ponds

075 MARIA SAHUQUILLO AND MARIA ROSA MIRACLE. Crustacean and rotifer seasonality in a Mediterraneantemporary pond with high biodiversity (Lavajo de Abajo de Sinarcas, Eastern Spain)

093 SANDRINE ANGELIBERT, VERONIQUE ROSSET, NICOLA INDERMUEHLE AND BEAT OERTLI. The pondbiodiversity index “IBEM”: a new tool for the rapid assessment of biodiversity in ponds from Switzerland.Part 1. Index development

105 NICOLA INDERMUEHLE, SANDRINE ANGELIBERT, VERONIQUE ROSSET AND BEAT OERTLI. The pondbiodiversity index “IBEM”: a new tool for the rapid assessment of biodiversity in ponds from Switzerland.Part 2. Method description and examples of application

121 OLIVIER SCHER, KATE E. MCNUTT AND ALAIN THIERY. Designing a standardised sampling method forinvertebrate monitoring: a pilot experiment in a motorway retention pond

133 MARIA ANTON-PARDO AND XAVIER ARMENGOL. Zooplankton community from restored peridunal pondsin the Mediterranean region (L’Albufera Natural Park, Valencia, Spain)

145 ALFONSO GARMENDIA AND JOAN PEDROLA-MONFORT. Simulation model comparing the hydroperiod oftemporary ponds with different shapes

153 DAVID LEON, PATRICIO PENALVER, JESUS CASAS, MELCHOR JUAN, FRANCISCA FUENTES, IRENEGALLEGO AND JULIA TOJA. Zooplankton richness in farm ponds of Andalusia (southern Spain). Acomparison with natural wetlands

163 NATALIA KUCZYNSKA-KIPPEN AND TOMASZ JONIAK. Chlorophyll a and physical-chemical features ofsmall water bodies as indicators of land use in the Wielkopolska region (Western Poland)

171 ANNA BASINSKA, NATALIA KUCZYNSKA-KIPPEN AND KASPER SWIDNICKI. The body size distribution ofFilinia longiseta (Ehrenberg) in different types of small water bodies in the Wielkoposka region

MANUELA. S. GRAÇA. Coimbra · resumen Prefacio: conservacion de las charcas europeas-conocimiento...

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