Elemental stoichiometry of freshwater fishes in relation to phylogeny, allometry and ecology

Twenty species of freshwater fishes were collected from Minnesota. Iowa and Michigan and their whole-body carbon, nitrogen and phosphorus contents and the respective C:N:P ratios were determined. Patterns were examined ill intra- and interspecific variation, allometry and variation caused I)v habitat and trophic level ill whole fish while controlling, I'm the role of phylogeny. Stoichiometric variation was greater across than within species, C:N:P allometry was species-specific. nutrient content within a species was somewhat habitat-specific and P concentration showed a strong phylogenetic signal. Stoichiometric relationships with allometry and feeding guild were observed but were not significant in an analysis accounting for non-independence of closely related species. Supportive evidence for the hypothesis that the considerable variation in whole fish phosphorus concentrations could he ascribed to differences ill bone and scale development, as previously suggested, is shown. Whole fish Ca:P ratios had a nearly constant stoichiometry consistent with the chemical signature of bone. This result combined with a signal for fish P indicated that the great stoichiometric variability among fish taxa phylogenetic signal for fish P indicated that the great stoichiometric variability among fish taxa in P content was derived almost entirely from skeletal investments. ill P content was derived almost entirely from skeletal investment. (c) 2007 The Authors Journal compilation (c) The Fisheries Society of the British Isles.