ý'} ^ýý4. EFFECTS OF COPPERON THE ENERGY BUDGET OF A STREAM DETRITIVORE: VALIDATION AND ECOLOGICAL RELEVANCE. LISA JOANNE TATTERSFIELD. THESIS SUBMITTED TO THE UNIVERSITY OF SHEFFIELD FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE DEPARTMENT OF ANIMAL AND PLANT SCIENCES. FEBRUARY 1993. ý'-ý, 1 This work was supported by a case studentship funded by the Natural Environment ResearchCouncil and Shell U. K. I am indebted to my supervisors Dr Lorraine Maltby and Prof. Peter Calow at the University of Sheffield and Dr Andy Girling at the Shell Research Centre. I am particularly grateful to Lorraine for all her hard work over the last three years. Analytical chemistry was conductedby Andy Fairburn and Paul Cooke. Image analysis and scanning electron microscopy were performed at Shell by Sue Lee to whom I am also grateful for her friendship during periods of time spent at the Shell ResearchCentre. I am also very grateful for support from Dr Richard Stephenson,Dr Gary Mitchell, Neil Pearsonand Joy Worden at the Shell ResearchCentre. Fungal cultures were provided by Sue Bermingham to whom I am also grateful for help with fungal techniques. My thanks goes to Ruth Sherratt for introducing me to the scope for growth techniques. I am also grateful for technical support at various periods during the course of my study from many technicians in the Department of Animal and Plant Sciences at the University of Sheffield. I would like to thank all the members of the 'Freshwater Group' at the University of Sheffield, I particularly appreciate support from Dave Forrow and Sue Bermingham. I would also like to acknowledge the continued interest from and inspiration given by Dr JohannaParry from the University of Lancaster. Finally, but by no means least, my thanks go to my parents for their love and their constant support and encouragementthroughout my university career. .` =_ ii EFFECTS OF COPPER ON THE ENERGY BUDGET OF A STREAM DETRITIVORE: VALIDATION AND ECOLOGICAL RELEVANCE. LISA JOANNE TATTERSFIELD. It is undisputedthat singlespecies toxicity testsare essential for obtaininginformation on concentrationsand durationsof exposuresto chemicalsthat result in changesin survival, reproduction, physiology, biochemistry and the behaviour of individuals within a particular species(Caims, 1983).However, the extent to which single speciestoxicity testscan be usedto predicteffects in the naturalenvironment and changes at higherlevels of biological organizationare largely unknown(Kooijman, 1985).The ultimate aim of laboratorytests is to predict the potentialeffects of toxicantsin natural systemsin order to protectthe structureand functioning of theecosystem. Hence, the aim of this studywas to investigatethe validity (i.e. the extentto which effectsobserved in the laboratoryare mirroredin a morenatural environment) and ecological relevance (i. e. the extentto which the testsare indicativeof effectsat higherlevels of organisationwhich areimportant for the structure and / or functioning of the ecosystem)of a particular single species laboratorytest. In order to increaseits potential ecologicalrelevance, both test speciesand response criteria for the laboratorytest werecarefully selected.The effectsof copper,a reference toxicant, on energy budget parametersof Gammaruspulex, an important stream detritivore, were investigated.The validity and ecologicalrelevance of these energy budgettests, under more naturalconditions, were investigatedwith the use of outdoor artificial streams. In the laboratorytests, consumption rates were identified as the most sensitiveenergy budgetparameter to copper-inducedstress in G.pule-x. This decreasein consumptionrates was due to an increasein the body copperconcentration of G.pulex via copperuptake from the media,rather than to a rejectionof coppercontaminated food. As well as being the most sensitiveparameter to copper stressin laboratory tests, consumptionrates were identified as the most sensitive energy budget parameter measuredin animalsdeployed in the artificial streams.Further, there was no statistically significantdifference between the effectsof copperon consumptionrates of animalsin laboratorytests and in the artificial streams.Therefore tests based on consumptionrates as a responsecriterion were valid in morenatural systems. Potential additional effects on the consumptionrates of G.pulex due to copper-inducedreductions in food quality were alsoindicated. The ecologicalrelevance of thesetests was investigatedby trying to predict higherlevel effectsin termsof growth and reproductionof whole organismsin the laboratoryand in terms of the structure and functioning of populationsand communitiesin artificial streams.Predictions regarding effects of copperon growth and reproductionof whole organismswere fairly accuratein indicating trendsbut were unsuccessfulin predicting actualgrowth rates and reproductive output. Populationdensity and leaf processingwere selectedas responsecriteria indicative of effectsof copperon the structureand functionof the freshwaterecosystem respectively. Effects on thesetwo parameterswere observedat the sameconcentration as adverse effects on consumptionrates, and no adverseeffects were detectedat concentrations below those causinga decreasein consumptionrates. Potential consequences,of the observedeffects of copperon G.pulax, for the structureand functioning of the freshwater communityare discussed. iii It is concluded that by careful selection of ecologically meaningful responsecriteria and test species, laboratory tests based on individuals can be representative of potential impact of a toxicant at higher levels of organisation in the natural environment. Consumption rates in G.pulex represent a sensitive, valid and ecologically relevant responsecriterion for the determination of the effects of a pollutant in natural ecosystems. CONTENTS Acknowledgements ..................................... i. Abstract ............................................ ii. CHAPTER 1. GENERAL INTRODUCTION. 1.1. Introduction 1 . ...................................... 1.2. Test 2 species....................................... 1.3. ResponseCriteria 5 .................................... 1.4. Reference 7 toxicant................................... 1 5 A h 9 . pproac ......................................... CHAPTER 2. EFFECTS OF COPPER ON THE ENERGY BUDGET OF GAMMARUS PULEX. 2.1. Introduction....... 10 ............................. 2.2. Objectives. 12 ..... .................................... 2.3. Materials 13 and methods................................. 2.3.1. Collection 13 of test animals........................... G. in laboratory 13 2.3.2. Maintenanceof pulex the .................. Media 13 a. ..................................... b. Food 14 ..................................... Holding 15 c. conditions............................. d. Test solutions................................ 15 2.3.3. Survivorship. 17 2.3.4. EnergyBudget ................................. 17 a. Consumptionand faecal 17 production................... b. Jouleequivalent of food faeces 20 and ................... Standard 22 c. respiration rate .......................... d. Absorption for 24 and scope growth ..................... 2.3.5. Active feeding 25 and respiration rates..................... Active 25 a. respiration rate........................... b. Feeding 26 respiration rate.......................... 2.3.6., Behavioural detection food 27 and selectionof ............... 2.3.7. Body 29 copper concentration.......................... 2.3.8. Uptake 30 route of copper............................ 2.4. Statistical 31 analyses................................ 2 5 R l 33 . esu ts.......................:............... 2.5.1. Survivorship 33 .................................. 2.5.2. Energy budget 33 ................................. Consumption faecal 33 a. and production. .. ý................ b. food faeces 35 Joule equivalent of and ................... Standard 36 c. respiration rate.......................... for 36 d. Absorption and scope growth..................... 2.5.3. Active feeding 38 and respiration........................ Active 38 a. respiration.............................. b. Feeding 39 respiration............................. 2.5.4. Overall budget 42 energy ............................. food 43 2.5.5. Behavioural detection and selection of ................ 45 2.5.6. Body copper concentration.......................... 47 2.5.7. Uptake route of copper............................ 2.6. Discussion 51 ..................................... 2.7. Summary 61 ...................................... CHAPTER 3. EFFECTS OF COPPERON GROWTH AND REPRODUCTION. 3.1. Introduction 63 ....................................... Growth 63 a. .................................... b. Reproduction 65 ................................ 3 2 Object i 70 . ves................... ...................... 3.3. Materi l d h d 70 a s an met o s................................. 3 3 1 G h 70 . rowt ....................................... Parameter d 70 a. measure ............................ juvenile 71 b. Effect of copper on growth rates................ juvenile 73 c. Prediction of growth rates.................... 3.3.2. Reproduction 76 .................................. brooding females 76 a. Sensitivity of to copper................ 76 b. Effect of copper on reproduction..................... Brood 78 c. cannibalism............................. 79 d. Prediction of reproductive output..................... 3.4. Statistical 82 analyses................................... 3.5. Results 83