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 zooplankton and terrestrial insects, and indicate that the strength of stoichiometric constraints acting in littoral food webs will depend on the taxa being considered.