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Stable isotopes as an indicator of diet in omnivorous crayfish (Pacifastacus leniusculus): the influence of tissue, sample treatment, and season

  • Patrik Stenroth
  • Niklas Holmqvist
  • Per Nyström
  • Olof Berglund
  • Per Larsson
  • Wilhelm Granéli
Publishing year: 2006
Language: English
Pages: 821-831
Publication/Series: Canadian Journal of Fisheries and Aquatic Sciences
Volume: 63
Issue: 4
Document type: Journal article
Publisher: National Research Council Canada

Abstract english

Stable isotopes have been used to analyse food webs and (or) trace movements of animals for about 30 years. There has been some debate on the use of different tissues and treatments before isotope analysis, as well as on seasonal effects. We found different crayfish (Pacifastacus leniusculus) tissues (muscle, hepatopancreas, exoskeleton, gill, and whole body) to have different isotope values. Lipid extraction made whole-body carbon isotope values higher but had no effect on nitrogen isotope values. Acidification made whole-body isotope values lower. For crayfish, there was no seasonal or interannual variation in isotope values. In contrast to studies based on gut content analysis, we found adult crayfish to be at least as carnivorous as young-of-the-year crayfish. Earlier studies often have assumed that each food source contributes both nitrogen and carbon in equal proportions. Omnivores do not fit easily into this view. We suggest that nitrogen and carbon in an organism could come from different sources. Adopting this view for a pond food web could render crayfish both predators and detritivores as crayfish prey on nitrogen sources (other invertebrates) and consume large amounts of detritus to satisfy their carbon demand.


  • Ecology


  • ISSN: 1205-7533
Wilhelm Granéli
E-mail: wilhelm [dot] graneli [at] biol [dot] lu [dot] se

Professor emeritus

Aquatic ecology

+46 70 279 82 34