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  • Organisms and food webs in rock pools:Responses to environmental stress and trophic

    manipulation

    Marie Arn6r

    Department of Zoology, Stockholm UniversityS-106 91 Stockholm, Sweden

    Stockholm 1997

  • Doctoral dissertation 1997

    Marie Am&Department of ZoologyStockholm UniversityS-106 91 Stockholmmarie.arner@zoologi.su.se

    0 1997 Marie Am&ISBN 9 l-87272-53-9Printed by Jannes Snabbtryck AB, StockholmCover by Bibbi Mayrhofer

    2

  • ERRATAOrganisms and food webs in rock pools:

    Responses to environmental stress and trophic manipulationby

    Marie Arnerpage line writtenSummary6 9 (1992) Physiological and life

    history responses of Duphnia -magna to increasing salinity

    6

    1010111323

    13 (submitted manuscript)

    right 20 Koehn & Bayne 1988right 24 Koehn & Bayne 1988right 32 ..physiological index. (..left 21 (1996) has argued...left 22 Koehn R.K. &Bayne, B.L

    (1988)

    Paper III4 left 18 . ..The water was sieved..6 right 41 and nauplia to Cyclops

    Paper IV12 left 21 . . . Daphnia generally had lower

    biomass...

    Paper V3 right 8 of salinity tolerance of the

    DaphnM

    should be

    (1993) Effects of salinityon metabolism and lifehistory characteristics ofDaphnia magna(accepted for publication inFreshwater Biology)Koehn & Bayne 1989Koehn & Bayne 1989..physiological index (...(1996) have argued...Koehn R.K. & BayneB.L (1989)

    The water (50 L tub-) was sievedand nauplia to total Cyclops

    . . . Duphnia generally had higherbiomass.. .

    of salinity tolerance of Daphnia

    5 right 24 The ratios of nauplia to Cyclops The ratios of nauplia to totalCyclops

  • To my family

  • Abstract

    Differential susceptibility of organisms and populations to environmental stress influ-ences the outcome of biological interactions and the structure of communities andecosystems. In this thesis, the effects of environmental stress on organism, populationand community levels were studied. Die physiological responses to changes in salinityand exposure to pollutants were studied by comparing rock pool Gammurus duebeni andlittoral G. oceanicus with different tolerance to abiotic stress. Physiological and lifehistory responses of rock pool Duphnia magna to different salinities were examined. Ex-,perimental systems, originating from natural rock pools, were established to exploredirect and indirect impacts of cadmium and predator addition in freshwater plankton com-munities. Three different food web configurations were used: 1. phytoplankton andsmall-bodied zooplankton (Cyclops sp. and Chydorus sphaericus), 2. phytoplankton,small-bodied zooplankton and D. magna, and 3. phytoplankton, small-bodied zooplank-ton, D. magna and the invertebrate predator Notonectu sp. To evaluate the experimentalsystems, natural and experimental rock pools were compared.

    Salinity stress negatively affected the physiological status of Gammurus and D.magna. G. duebeni, with higher tolerance to fluctuation in abiotic variables, was lessaffected by natural stress and pollutants than G. oceanicus. The physiological and lifehistory responses led to comparable conclusions in D. magna: i.e., salinity stressnegatively affected the physiological status of D. mugnu and hampered reproduction andgrowth. In the experimental food webs, cadmium inhibited phytoplankton productivityand decreased the biomass of cladocerans. Cadmium did not change the trophicinteractions between Duphniu and phytoplankton or between Duphniu and Notonectu.The regulation of lower trophic levels by Duphniu and Notonecta was important in theexperimental food webs. Notonectu produced a indirect positive (cascade) effect onphytoplankton and small-bodied zooplankton. It was possible to maintain experimentalphytoplankton-herbivore communities for several months. The experimental systemsresembled natural rock pools with permanent D. mugnu presence. Phytoplanktonbiomass was regulated by D. magna when the species was permanently present in bothnatural and experimental rock pools. Experimental rock pools may approximate otherfishless habitats and the spatial and temporal scales are most appropriate for studies ofplankton interactions.

    4

  • Organisms and food webs in rock pools:Responses to environmental stress and trophic manipulation

    Akademisk avhandling som for avlaggande av filosofie doktorsexamen vid StockholmsUniversitet offentligen forsvaras torsdagen den 29 maj 1997, kl. 10.00 ifiirelfsningssalen, Frescati Backe, Svante Arrhenius vag 21 A, Frescati

    MarieavArnCr

    Zoologiska InstitutionenStockholms UniversitetS-106 91 Stockholm

    Stockholm 1997ISBN 9 l-87272-53-9

    AbstractDifferential susceptibility of organisms and populations to environmental stress influ-ences the outcome of biological interactions and the structure of communities andecosystems. In this thesis, the effects of environmental stress on organism, populationand community levels were studied. The physiological responses to changes in salinityand exposure to pollutants were studied by comparing rock pool Gummurus duebeni andlittoral G. oceanicus with different tolerance to abiotic stress. Physiological and lifehistory responses of rock pool Duphniu magna to different salinities were examined, Ex-perimental systems, originating from natural rock pools, were established to exploredirect and indirect impacts of cadmium and predator addition in freshwater plankton com-munities. Three different food web configurations were used: 1. phytoplankton andsmall-bodied zooplankton (Cyclops sp. and Chydonrs sphuericus), 2. phytoplankton,small-bodied zooplankton and D. magna and 3. phytoplankton, small-bodied zooplank-ton, D. mugnu and the invertebrate predator Nofonectu sp. To evaluate the experimentalsystems, natural and experimental rock pools were compared.Salinity stress negatively affected the physiological status of Gummunrs and D. mugnu.G. duebeni, with higher tolerance to fluctuation in abiotic variables, was less affected bynatural stress and pollutants than G. oceunicus. The physiological and life history res-ponses led to comparable conclusions in D. magna: i.e., salinity stress negatively aflec-ted the physiological status of D. magna and hampered reproduction and growth. In theexperimental food webs, cadmium inhibited phytoplankton productivity and decreasedthe biomass of cladocerans. Cadmium did not change the trophic interactions betweenDuphniu and phytoplankton or between Duphniu and Notonectu. The regulation of lowertrophic levels .by Duphniu and Notonectu was important in the experimental food webs.Notonectu produced a indirect positive (cascade) effect on phytoplankton and small-bodied zooplankton. It was possible to maintain experimental phytoplankton-herbivorecommunities for several months. The experimental systems resembled natural rockpools with permanent D. magna presence. Phytoplankton biomass was regulated by D.mugnu when the species was permanently present in both natural and experimental rockpools. Experimental rock pools may approximate other fishless habitats and the spatialand temporal scales are most appropriate for studies of plankton interactions.

  • Table of contents

    List of papers

    Introduction

    The rock pool ecosystem

    Environmental stress- Background- Rock pool organisms and effects of salinity

    changes and toxicants

    Model systems and experimental rock pools- Background- The experimental rock pool systems: experienceand evaluation

    Consumer and resource regulation- Experience from lake and experimental studies- Predation and competition in rock pool systems- Consumer regulation of lower trophic levels byNotonecta and Daphnia in experimental rock pools

    - Effects of cadmium addition on trophic interactionsin rock pool food webs

    Conclusions

    References

    Acknowledgements

    1012

    1313

    151617

    18

    18

    19

    27

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  • List of papers

    The following papers are included in this thesis and will be referred to in the text bytheir Roman numerals. The published and accepted papers are reprinted with kindpermission of the publishers. .

    I

    II

    III

    IV

    V

    Tedengren M., Am& M. & Kautsky N. (1988) Ecophysiology and stressresponse of marine and brackish water Gammarus species (Crustacea,Amphipoda) to changes in salinity and exposure to cadmium and diesel-oil.Mar. Ecol. Prog. Ser. 47:107-l 16

    ArnCr M. & Koivisto S. (1992) Physiological and life history responses ofDaphnia magna to increasing salinity. Hydrobiologia 259: 69-77

    ArnCr M., Koivisto S., Norberg J. & Kautsky N. Trophic interactions in rockpool food webs: regulation of zooplankton and phytoplankton by JVutonectaand Daphnia. (submitted manuscript).

    Koivisto S., ArnQ M. & Kautsky N. (1997) Does cadmium pollution changetrophic interactions in rockpool food webs? Accepted for publication inEnviron. Toxicol. Chem.

    Am& M. & Koivisto S. Evaluation of the ecological relevance of a modelsystem: Seasonal development and patterns in natural and experimental rockpools (manuscript).

    6

  • Introduction

    Rock pools, water filled bed-rockdepressions, are patches of habitatdifferent from the surrounding shore aridare found on shores around the world.They are characterised by large spatial andtemporal variations and are considered asphysically harsh habitats (Ganning 197 1;Ranta 1982; Astles 1993; Metaxas &Scheibling 1993; Loder et al. 1996;Underwood & Skilleter 1996). Theseisolated habitats are commonly foundalong the Swedish and Finnish coastalareas of the Baltic Sea. Earlier studies ofrock pools in the Baltic Sea area haveemphasised species composition andabundance in relation to the phy