Elemental Composition of Littoral Invertebrates from Oligotrophic and Eutrophic Canadian Lakes

The P, N, and C content of littoral macroinvertebrates from 8 lakes located in 3 distinct geographical regions of Canada (central Alberta, northwestern Ontario, and Rocky Mountains near Jasper, Alberta) is described. A wide range of values was found in the body content (all values are % of dry mass) of P (0.4-1.6%), N (5.8-13.7%), and C (32.5-53.5%) in the data set containing invertebrates from all 8 lakes. C:P (63-324), N:P (9.6-60), and C:N (4.2-7.6) (all by atom) also varied widely. This variation was partly related to the different mean body content of P, N, and C among taxonomic groups. However, the mean P, N, and C content of macroinvertebrate assemblages varied little among lakes. The patterns of elemental composition in benthic invertebrates shown here are similar to zoo-plankton and terrestrial insects, and indicate that the strength of stoichiometric constraints acting in littoral food webs will depend on the taxa being considered.