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The Biology of Temporary Waters D. Dudley Williams University of Toronto at Scarborough, Canada 1 1 GreatClarendonStreet,OxfordOX26DP OxfordUniversityPressisadepartmentoftheUniversityofOxford. ItfurtherstheUniversity’sobjectiveofexcellenceinresearch,scholarship, andeducationbypublishingworldwidein Oxford NewYork Auckland CapeTown DaresSalaam HongKong Karachi KualaLumpur Madrid Melbourne MexicoCity Nairobi NewDelhi Shanghai Taipei Toronto Withofficesin Argentina Austria Brazil Chile CzechRepublic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore SouthKorea Switzerland Thailand Turkey Ukraine Vietnam OxfordisaregisteredtrademarkofOxfordUniversityPress intheUKandincertainothercountries PublishedintheUnitedStates byOxfordUniversityPressInc.,NewYork #OxfordUniversityPress2006 Themoralrightsoftheauthorhavebeenasserted DatabaserightOxfordUniversityPress(maker) Firstpublished2006 Allrightsreserved.Nopartofthispublicationmaybereproduced, storedinaretrievalsystem,ortransmitted,inanyformorbyanymeans, withoutthepriorpermissioninwritingofOxfordUniversityPress, orasexpresslypermittedbylaw,orundertermsagreedwiththeappropriate reprographicsrightsorganization.Enquiriesconcerningreproduction outsidethescopeoftheaboveshouldbesenttotheRightsDepartment, OxfordUniversityPress,attheaddressabove Youmustnotcirculatethisbookinanyotherbindingorcover andyoumustimposethesameconditiononanyacquirer BritishLibraryCataloguinginPublicationData Dataavailable LibraryofCongressCataloginginPublicationData Williams,D.Dudley. Thebiologyoftemporarywaters/D.DudleyWilliams. p. cm. Includesbibliographicalreferencesandindex. ISBN 0–9–852811–6(hardback:alk.paper)—ISBN0–19–852812–4 (paperback:alk.paper) 1. Aquaticecology. 2. Aquatichabitats. I. Title. QH541.5.W3W4492006 577.6—dc22 2005019559 TypesetbyNewgenImagingSystems(P)Ltd.,Chennai,India PrintedinGreatBritain onacid-freepaperby AshfordColourPress,Hampshire ISBN0–19–852811–6 978–0–19–852811–1 ISBN0–19–852812–4(Pbk.) 978–0–19–852812–8(Pbk.) 1 3 5 7 9 10 8 6 4 2 Preface Temporarywatersarefascinatingvenuesinwhich the applied, to the conceptual. Each has contri- tostudythepropertiesofspecies,asthelatterdeal buted something to our knowledge base, yet this with the day-to-day business of living in a highly information remains largely scattered, in need of variable environment. Obligate temporary water collation and synthesis. Several worthwhile species display a remarkable array of adaptations attemptshavebeenmadethrough‘specialsessions’ to the periodic loss of their primary medium that atrecentconferences,however,thereremainslittle largely sets them apart from the inhabitants of integration. Perhaps, the available data remain a permanent water bodies. Survival of individuals littletoopatchyandthesubdisciplineisstillalittle frequently depends upon exceptional physio- too immature for a thorough treatment, but hope- logical tolerance or effective migrational abilities, fullythisbookisastepinthatdirection. and communities have their own, distinctive hall- Ihavemanypeopletothankforhelpingmeput marks. Quite apart from their inherent biological this volume together. First and foremost are sev- interest,however,temporarywatersarenowinthe eralofmypastandpresentgraduatestudentsand limelight from a conservation perspective as these postdoctoral fellows who have shared my interest habitats come more and more into conflict with intemporarywaters,andwhohaveallowedmeto human activities. Traditionally, many temporary use some of their unpublished data. In particular, waters,betheyponds,pools,streams,orwetlands, Katarina Magnusson and Oksana Andrushchy- havebeenconsideredtobe‘wasted’areasofland, shyn have provided information on intermittent potentiallyconvertibletoagricultureoncedrained. pond faunas in southern Ontario (Chapter 4), and In reality, they are natural features of the global Ian Hogg has kindly provided information on the landscape representing distinct and unique habi- faunal changes along the Murrumbidgee River, tats for many species—some that are found Australia (Chapter 10). I am also grateful to those nowhere else, others that reach their maximum colleagues who have allowed me to reproduce abundance there. photographs and figures from their published In1985,thelateW.D.Williamslamented‘....The works,andwhoareacknowledgedbynameinthe extent of reference to temporary waters is not in figure legends. Several of these same colleagues accord with their widespread occurrence and also provided encouragement to undertake the abundance,ecologicalimportance,norlimnological writingofthisbook,andIhopethatthecompleted interest’. In 1987, I published ‘The Ecology of product does not disappoint them. I would also Temporary Waters’ which was a first attempt to like to formally thank Diane Gradowski and Ken gather together the highly scattered literature on Jones of the University of Toronto at Scarborough these fascinating habitats. Gratifyingly, since Bill graphics department for their help with many Williams’lamenttherehasbeenasteadyincreasein of the illustrations, and the Natural Sciences and thestudyoftemporarywaters,andmanyresearch Engineering Research Council of Canada for articleshavebeenpublishedthroughouttheworld. financial support of my research. Thanks, too, go The latter range from the highly descriptive, to to Annette Tavares for the cover design. vii viii PREFACE On a personal note, I am grateful to my family, thought, and to Bronwen for always being happy Judy, Siaˆn, and Owen, whose support and com- to see me. panionship helped me complete what turned out D. Dudley Williams to be a far bigger project than I had originally Toronto, May 2005 Contents 1 Introduction 1 1.1 Whataretemporary waters?.. ..... .... .... .... .... .... ..... .... .... .... .... ... 1 1.2 Biologicalimportance... .... ..... .... .... .... .... .... ..... .... .... .... .... ... 1 1.3 Classificationoftemporary waters .. .... .... .... .... .... ..... .... .... .... .... ... 3 1.4 Importanceoftemporary watersinthelandscape .. .... .... ..... .... .... .... .... ... 9 2 Thephysicalenvironment 12 2.1 Hydrological considerations.. ..... .... .... .... .... .... ..... .... .... .... .... .. 12 2.2 Origins:basinandchannelformation.... .... .... .... .... ..... .... .... .... .... .. 18 2.3 Climate,seasonality,andhabitatpersistence... .... .... .... ..... .... .... .... .... .. 21 3 Influentialenvironmental factors 25 3.1 Introduction .. .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 25 3.2 Waterbalance. .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 25 3.3 Watertemperatureandturbidity ... .... .... .... .... .... ..... .... .... .... .... .. 30 3.4 Dissolvedoxygenandcarbondioxide ... .... .... .... .... ..... .... .... .... .... .. 32 3.5 Otherchemicalparameters... ..... .... .... .... .... .... ..... .... .... .... .... .. 33 3.6 Substrate. .... .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 35 3.7 Light.... .... .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 36 3.8 Biologicalfactors. .. .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 37 4 Thebiota 40 4.1 Introduction .. .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 40 4.2 Taxa .... .... .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... .. 40 4.3 Thetemporary watercommunity—globalscalecomparisons .. ..... .... .... .... .... .. 85 4.4 Thetemporary watercommunity—localscalecomparisons ... ..... .... .... .... .... .. 93 CaseHistories—Intermittent Waters.. .... .... .... .... ..... .... .... .... .... .... . 93 CaseHistories—Episodic Waters .... .... .... .... .... ..... .... .... .... .... .... . 108 4.5 Globalcommonalityamongcommunities. .... .... .... .... ..... .... .... .... .... .. 114 4.6 Permanentversustemporary waterfaunas.... .... .... .... ..... .... .... .... .... .. 116 4.7 Insectsversus crustaceansversus‘therest’.... .... .... .... ..... .... .... .... .... .. 119 5 Populationdynamics 121 5.1 Introduction .. .... .... .... ..... .... .... .... .... .... ..... .... .... .... .... . 121 5.2 Seasonalityandvariabilityinlifecycles .. .... .... .... .... ..... .... .... .... .... . 123 5.3 Phenotypicandgenotypicvariation . .... .... .... .... .... ..... .... .... .... .... . 130 5.4 Physiologyofdesiccation .... ..... .... .... .... .... .... ..... .... .... .... .... . 134 ix x CONTENTS 5.5 Adaptations .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 137 5.6 Adaptive‘strategies’ofcolonizingorganisms.... .... .... .... .... .... ..... .... .. 150 5.7 Activecolonization... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 151 5.8 Passivecolonization .. .... .... .... .... ..... .... .... .... .... .... ..... .... .. 159 6 Communitydynamics 163 6.1 Introduction .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 163 6.2 Communitysuccession.... .... .... .... ..... .... .... .... .... .... ..... .... .. 166 6.3 Colonizationandcompetition... .... .... ..... .... .... .... .... .... ..... .... .. 168 6.4 Temporarywatersasislandsintimeandspace .. .... .... .... .... .... ..... .... .. 172 6.5 Trophic relationships.. .... .... .... .... ..... .... .... .... .... .... ..... .... .. 175 7 Othertemporarywater habitats 187 7.1 Introduction .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 187 7.2 Phytotelmata.... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 188 7.3 Gastrotelmata ... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 203 7.4 Anthrotelmata... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 203 7.5 Snowfields ..... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 204 7.6 Marinelittoral pools.. .... .... .... .... ..... .... .... .... .... .... ..... .... .. 205 7.7 Reservoirs. ..... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 209 7.8 Deserts ... ..... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 209 7.9 Starfishes . ..... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 211 7.10 Dung .... ..... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 211 7.11 Commonalityamongpopulationsandcommunities... .... .... .... .... ..... .... .. 214 8 Applied aspectsoftemporarywaters 215 8.1 Introduction .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 215 8.2 Aquaculture/agriculturerotation—anancientart. .... .... .... .... .... ..... .... .. 215 8.3 Floodplains andfisheries .. .... .... .... ..... .... .... .... .... .... ..... .... .. 217 8.4 Ricepaddyfields .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 226 9 Habitatsforvectorsofdisease 230 9.1 Introduction .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 230 9.2 Whytemporary waters? ... .... .... .... ..... .... .... .... .... .... ..... .... .. 230 9.3 Temporarywater-facilitated diseases—who arethevectors?. .... .... .... ..... .... .. 230 9.4 Economic andhumanitarian costs.... .... ..... .... .... .... .... .... ..... .... .. 236 9.5 Eradicationvscontrol:vectorvshabitat... ..... .... .... .... .... .... ..... .... .. 238 9.6 Conclusions .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 247 10 Importance andstewardship oftemporary waters 248 10.1 Introduction .... .... .... .... .... .... ..... .... .... .... .... .... ..... .... .. 248 10.2 Roleinthenaturalenvironment. .... .... ..... .... .... .... .... .... ..... .... .. 248 10.3 Management andconservation.. .... .... ..... .... .... .... .... .... ..... .... .. 253 10.4 Triumphs,failures,and‘works inprogress’ ..... .... .... .... .... .... ..... .... .. 263 10.5 Conclusions andrecommendations... .... ..... .... .... .... .... .... ..... .... .. 266 References 269 Index 315 CHAPTER 1 Introduction 1.1 What are temporary waters? considerableattentionelsewhere(e.g.W.D.Williams 1981; Hammer 1986; International Society for Salt Wehaveshorttimetostay,asyou, Lake Research 2001). Coastal marine habitats, for WehaveasshortaSpring, example salt marsh ponds and supralittoral rock- Asquickagrowthtomeetdecay, Asyouoranything pools,arealsosubjecttodrying,andwillbetouched oninthisvolume. (RobertHerrick,1591–1674) The physicochemical features of temporary Temporary waters, in general, are to be found waters strongly influence the biotas present, but throughout the world. Some types, such as the biologicalfactorsmaybeimportantalsoespecially reservoirs of bromeliad leaf axils and turloughs with increased duration of the aquatic phase. (seasonallimestonelakes),arerestrictedbyfactors Insects and crustaceans tend to dominate the such as climate or geology. Others, such as tem- fauna, but temporary water communities, as a porary ponds and streams, and rain pools are whole,maycomprisebacteria,protoctists,vertebr- ubiquitous—althoughthese,too,mayexhibitsome ates,fungi,andanabundanceofhigherandlower regional differences (e.g. rain pools characterize plants. Many species exhibit opportunistic and the high, open grasslands of South Africa). How- pioneering traits, and also a range of drought- ever, all are, for the most part, natural bodies of survival mechanisms, such as diapause and seed water which experience a recurrent dry phase. formation. Often, the latter is predictable both in its time of Whereas wetlands, in general, comprise a very onset and duration. The defining element is the important subset of temporary waters, and data cyclical nature of the drought, as some permanent fromtheirstudywillbedrawnonthroughoutthis waterbodies may dry up in exceptional years. In book,thelatterisnotintendedasacomprehensive the latter case, because most of the biota is not synthesis of wetland biology per se. For such adapted to survive such conditions there will be information the reader is directed to, for example: significant mortality. Temporary water species,on Williams (1993), Finlayson and Van der Valk the other hand, are generally well adapted to (1995), Mitsch and Gosselink (2000), Spray and dealing with water loss. Indeed, many species McGlothlin (2004), and the websites of organiza- have spread beyond the boundaries of natural tionssuchastheRamsarConventiononWetlands waterbodies to colonize those temporary waters (http://www.ramsar.org/), and Wetlands Inter- that have been created by human culture, such as national (http://www.wetlands.org/). bird baths, and rainwater-filled tin-cans and tyre tracks. Although the contents of this book are 1.2 Biological importance devoted largely to temporary fresh waters, it is important to remember that a great number of Despite perhaps being regarded as the cinderellas inlandsalinewatersalsoexperiencedrought.Such of aquatic science, temporary waters represent habitats are widespread and they have received significant components of the global landscape. 1 2 THE BIOLOGY OF TEMPORARY WATERS From a cultural perspective, cyclically fluctuating of the ‘permanent’ biota that developed adapta- water levels often have determined the sustain- tions to resist desiccation and good powers of abilityandevolutionofripariansocieties.Aprime dispersal (Wiggins et al. 1980). The alternative example is the annual flooding of the River Nile viewpoint considers most permanent lakes to be upon which the agricultural activities of both geologically ephemeral (few are older than 20,000 ancient and modern civilizations have depended. years) and regards temporary water bodies as Further,fromaresourceperspective,wetlands,for being very ancient, not as individuals but as a example, represent a significant store of our pla- habitat type. Williams cited Lake George, a tem- net’sfreshwaters.However,temporarywatersalso porary freshwater lake near Canberra, Australia, have considerable significance to Biology per se. asbeing10millionyearsold.Hehypothesizedthat Blaustein and Schwartz (2001) outlined four rea- fromriversandtheterrestrialenvironment,alarge sons for studying temporary pools, specifically, contingent of the biota first colonized temporary but which well encompass other temporary water freshwaters (perhapstemporary floodplain pools), types: (1) temporary waters can contribute to our andthatasubsetofthisfloraandfaunadeveloped, general understanding of ‘ephemerality’, espe- or regained, the ability to withstand permanent cially as it relates to life histories, population inundation and hence were subsequently able to dynamics, and community organization; (2) these establish themselves in permanent lakes. Under habitats represent convenient systems in which to such a scenario, Williams stated that one would study ecological concepts, particularly as they are expecttoseesomeofthefollowingproperties:the amenable to manipulation experiments, and their more evolutionary ancient groups of the biota abundance allows easy replication. Further, those should occur in temporary waters; much of the habitats with simple communities can be mim- biota living in permanent waters should retain icked in semi-natural or even artificial set-ups; effective dispersal mechanisms—to counter the (3)temporarywatersfrequentlyharbourthevectors geological ephemerality of their habitats and as a of disease-causing organisms that afflict mankind; reflection of their lineage; many of the ‘active and (4) temporary waters contain many species migrants’ of the permanent lentic biota, should important to global biodiversity. persist in lotic habitats, or have close relatives To these may be added: (5) that, in a biogeo- which do; and overall species richness in tempor- graphicalcontext,thereisevidencetosuggestthat ary waters should be greater than in permanent temporary ponds may have acted as postglacial freshwaters.Evidencefromtheliteratureprovides dispersal routes for taxa possessing dormant some support for each of these properties (Tasch stages capable of ‘island-hopping’ (e.g. copepods) 1969; Elgmork 1980; Fernando 1980; Schram 1986; from glacial refugia (Stemberger 1995); (6) in an Fernando and Holc´ık 1989; Lake et al. 1988); evolutionarycontext,therehasbeenexplorationof (7)withincreasinginterestinland-waterecotones, the ideathatlifemayhaveevolved onearthmore themarginsoftemporarypondsandstreamshave thanonce,andthatanalternativeenvironment-of- the potential to be important sites for modelling origintotheoceansmayhavebeenpondsthatdry hydrological processes, nutrient transport and out periodically. In such ponds, chemicals in transformation, and the role played by the biota solution would have been progressively con- (BradleyandBrown1997;GiudicelliandBournard centrated to a state that enabled the maintenance 1997); and (8) there is now evidence to indicate of protoplasmic systems (Hinton 1968). Further, that variations in the physical environment of W.D. Williams (1988) has suggested that there is inlandwatersimpactbothmolecularandmorpho- an alternative explanation to the hypothesis that logical evolution by changing mutation rates thebiotaofpermanent,standingfreshwaterscame and by exposing (through genotype–environment from marine ancestors via either the terrestrial interactions) otherwise cryptic variation. Extreme environment, rivers or estuaries, and which releg- environments tend to accelerate morphological atesthebiotaoftemporaryfreshwaterstoasubset change, promoting diversification (Hebert 1999). INTRODUCTION 3 Temporary waters may be important sites of such Lengthandintensityofthedryperiodalsohave alteredratesofmolecularevolutionand,therefore, been suggested as criteria, and may be more bio- worth further study. logically relevant. Length of the dry phase can be divided simply into seasonal, annual, and greater thanannual—butcyclical.Intensityofthedrought 1.3 Classification of temporary waters is important because, for example, two habitats which both remain dry for 4 months of the year 1.3.1 Review of some previous classification might have different moisture-retaining capacities schemes of their substrates, allowing the survival of sig- Temporary waters are amazingly diverse in the nificantly different biotas. Climatologists have habitatsthattheypresentforthedevelopmentand deriveda numberofindices for droughtthatmay sustainmentoflife.Bywayofanexample,Table1.1 haveusefulapplication totemporary waters.One, lists the main types of temporary standing waters widely used example is the Palmer Hydrologic tobefoundintheBritishIsles.Itsubdividesthese Drought Index, which combines precipitation habitats into those of natural origin (e.g. peatland and temperature values with soil water content poolsandcupfungi;Figure1.1)andthoseresulting data—including outflow and storage measures fromhumanactivities(e.g.quarrypondsandsaw- (Heddinghaus and Sabol 1991). Some researchers pit ponds), and also distinguishes common from have found significant correlations between this rarer,orregional,types.Includinglotictemporary index and temporary water invertebrate popula- waters would swell the list considerably. Faced tion dynamics (Hershey et al. 1999). withsuchaninventory,itisperhapslittlewonder As with all systems of classification, there are that classification attempts for temporary waters boundtobeexceptionswhichdonotfitanyofthe are few and far between. One proposal has been categories, for example, Lake Eyre in southern baseduponhabitatsize(micro-,meso-,andmacro-; Australia only fills with water every half century Table1.2)butthistendstolumphabitatsthatmay or so (Mawson 1950). Can this really be called support quite different communities, for example cyclical? The majority of species that would col- lowland,floodplainpoolsandalpinelakes. onizesuchalakewoulddiewhenitdriedup,with Table1.1 ThemaintypesoftemporarystandingwaterfoundinBritain Naturalorigin Commontypes:Intermittentandepisodic(‘seasonal’)ponds,lakes;marginsofpermanentpondsandlakes;floodplainponds;oxbowponds; deltaicponds;tidalwetlands;supralittoraltidepools;peatlandpools;woodlandpools;vernalponds(filledonlyinspring);autumnalponds (summer-dry);rainpools(bothinclaysoilsandcrevicesinbedrock);poolsassociatedwithuprootedtreesandlandsurfaceundulations; emptysnailshells;water-filledhoof-prints;liquiddung. Rarerand/orregionaltypes:Pondsassociatedwithglacialactivities(e.g.kettleponds,formedbysubsidenceresultingfrommeltingof subsurfaceice,andmoraineponds,formedinglaciallydepositedsediments),solutionofbedrock,andironpans;turloughs(water-filled depressionsunderlainbylimestone);plungepools(formedatthebaseofdried-upwaterfalls);waterretainedbycupfungi,teasels andmosses;treeholes;waterretainedinlargeleafaxils. Humanorigin Quarrypools;poolsassociatedwithminingandlandscaping;wheel-rutpools;cattle-wateringpondsandtroughs;poolsresultingfrom peat-digging;waterfowl-decoychannels;fishponds;pondsassociatedwithancientruralactivities(e.g.dewponds,rainwater-collectionponds, armed/water-distributionponds,saw-pitponds,charcoal-burningpits);depressionsassociatedwithdefenceandwarfare(e.g.ditches, trenches,moats,bombcraters);rain-filledtyresandplasticsheeting(e.g.silageyards);middenpools;rainbarrels;cisterns;ornamental birdbaths;poolsassociatedwithlandfillsites;slurryvats;footprints;water-filled,cattle-trampleddepressions(e.g.aroundgatesand feedingareas). Source:InformationtakenfromRackham(1986)andWilliams(1987),wheregreaterdescriptionofthesevarioushabitatscanbefound. 4 THE BIOLOGY OF TEMPORARY WATERS Figure1.1 Photographofarainfilledcupfungus;notetheaccumulatedparticlesofdetritusthatmayserveasfoodforthebiota, andthepresenceofseveralsemi-aquaticoligochaetes. Table1.2 Classificationoftemporarywaterhabitatsbasedonsize Microhabitats:Axilsofplantleaves(e.g.bromeliads);treeholes;rain-filledrockpools;tincans;brokenbottlesandothercontainers;footprints; tyretracks;cisterns;emptyshells(e.g.molluscsandcoconuts) Mesohabitats:Temporarystreamsandponds;snow-meltpools;monsoonrainpools;floodplainpools;dewponds;wetlandpools Macrohabitats:Periodicallyflooded,largeoldriverbeds;shallowoxbowlakes,dryinglakes,dryinglakeshores,alpinelakes;sloughs;turloughs Source:AdaptedfromDecksbach(1929). perhapsonlyafew,highlyspecializedformsbeing Clearly it contained at least one species normally able to span the 50 or so years between fill ups. characterized as being indicative of temporary TheoccurrenceofsomewaterbodiesintheUnited waters. Kingdom affords another example of a misfit. Classifications based on indicator species, or Triops(anotostracan,ortadpoleshrimp),wasfirst speciesgroupsalsoarenotinfallible.Forexample, recorded in 1738 from a ‘temporary’ pond, it was Klimowicz (1959) attempted to classify small next recorded in 1837 and again in 1948, after a ponds in Poland on the basis of their molluscan lapse of 111 years (Schmitt 1971). Although it did faunas. Granted, some snail and bivalve species notappear,naturally,duringallthattime,itcould are very resistant to water loss and may be use- be hatched from dried mud taken from the pond fully assigned to different habitat types, however and rehydrated. This animal requires a period of some, such as Musculium partumeium, are known desiccation prior to hatching and the wet British to occur in both temporary and permanent ponds climate did not create suitable conditions very (Way et al. 1980). Colless (1957) modified a clas- often.Whethersuchapondcouldbetrulytermed sificationschemeofLaird’s(1956)basedonbreeding ‘temporary’,orwhetheritwassimplyapermanent habitatsformosquitoes.Init,hecreatedtwomain pond that dried up infrequently is debatable. categories—Surface Water, and Containers—the

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