Behavioural responses of benthic and pelagic Arctic charr to substratum heterogeneity

Authors

  • V. N. Mikheev,

    1. Fish Behaviour and Ecology Group, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
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    • *

      Present address: A. N. Severtsov Institute of Animal Evolutionary Morphology and Ecology, Russian Academy of Science, Leninsky Prospect 33, 117071 Moscow, Russia.

  • C. E. Adams,

    1. Fish Behaviour and Ecology Group, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
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  • F. A. Huntingford,

    1. Fish Behaviour and Ecology Group, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
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  • J. E. Thorpe

    1. Fish Behaviour and Ecology Group, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
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Abstract

Responses to environmental heterogeneity were studied in laboratory-reared offspring of two morphs of Arctic charr Salvelinus alpinus from Loch Rannoch, Scotland, one occupying the pelagic zone and feeding predominantly on zooplankton and the other being benthic in habit and feeding mainly on macroinvertebrates. When housed in groups in tanks with a black-and white striped base, benthic charr demonstrated a clear preference for dark areas, whereas pelagic fish positioned themselves at random with respect to substratum colour. In general, pelagic charr were much less aggressive than benthic charr. In pelagic fish, neither spacing nor aggression was affected by the visual heterogeneity of the substrate. In contrast, benthic charr swam closer together and fought more when housed over a uniform as opposed to a non-uniform substratum. The results are discussed in the context of habitat-specific visual requirements and of an interaction between visual complexity and territoriality previously described for Atlantic salmon Salmo salar.

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