Morphological, ecological and behavioural differentiation of sympatric profundal and pelagic Arctic charr (Salvelinus alpinus) in Loch Dughaill Scotland

Phenotypic variation in populations of fishes that inhabit postglacial lakes is often associated with trophic specialisations. A common sympatric foraging divergence seen in Arctic charr is into either plankton or littoral-zoobenthos feeding specialisms. In this study, we report a sympatric polymorp...

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Bibliographic Details
Published in:Hydrobiologia 2016-12, Vol.783 (1), p.209-221
Main Authors: Hooker, O. E., Barry, J., Van Leeuwen, T. E., Lyle, A., Newton, J., Cunningham, P., Adams, C. E.
Format: Article
Language:English
Subjects:
Animal behavior
Animal populations
Aquatic ecology
Biomedical and Life Sciences
Carbon isotopes
Charr II
Diphyllobothrium
Ecology
Fish
Fish populations
Fishes
Freshwater
Freshwater & Marine Ecology
Lakes
Life Sciences
Morphology
Pelagic zone
Phenotypic variations
Plankton
Salvelinus alpinus
Zoobenthos
Zoology
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Summary:Phenotypic variation in populations of fishes that inhabit postglacial lakes is often associated with trophic specialisations. A common sympatric foraging divergence seen in Arctic charr is into either plankton or littoral-zoobenthos feeding specialisms. In this study, we report a sympatric polymorphic Arctic charr population which is not centred on this divergence but instead manifests as a plankton (pelagic)—profundal zoobenthos foraging specialisms. The head shape of profundal fish was round and robust, the body thick set and pectoral fins long and wide. In contrast, the head of pelagic fish was pointed and slender, the body fusiform in shape and with short, narrow pectoral fins. There was no difference between profundal and pelagic fish in gill raker number. Body lipid content was significantly higher in pelagic fish as were the number or Diphyllobothrium cysts. The carbon isotope ratio was more heavily depleted in profundal fish. There was no dietary overlap in the prey items recovered from stomach contents of profundal and pelagic fish. We suggest the proximate driver behind the sympatric divergence was the successful exploitation of the profundal zone. The consequences of this have led to the development of adaptations in morphology and behaviour to support and maintain this divergence.
ISSN:0018-8158
1573-5117
DOI:10.1007/s10750-015-2599-0