title: Ontogenetic shift in crayfish δ13C as a measure of land-water ecotonal coupling.
abstract: Although ontogenetic changes in the carbon isotope ratios of marine fauna have been well studied those of freshwater organisms have not. As a result, we may have a less than adequate assessment of the incorporation of allochthonous detritus into freshwater foodwebs. This study found a δ13C range of 9‰ for crayfish (Orconectes virilis) from oligotrophic Canadian Shield lakes. Much (60-83%) of this variability was explained by body size. A simple isotopic mixing model suggests that by their third year of life, crayfish in these lakes rely more substantially upon terrestrial detritus than epilithic algae for energy.
authors.affiliation: Dep. of Biology, McGill University, 1205 Ave. Dr. Penfield, H3A 1B1, Montreal, Quebec, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: France
keywords: Allochthonous detritus; Crayfish; Ontogeny; δ13C