From June through October 1973, 335 samples of limnetic plankton were collected from 46 lakes and 17 rivers of the James Bay area. Sixty zooplanktonic species were identified (20 Copepoda, 27 Cladocera, and 13 Rotifera). The most common and widespread species are cold stenotherms (Leptodiaptomus minutus, Diacyclops bicuspidatus thomasi, Epischura lacustris, Holopedium gibberum, Bosmina longirostris, Daphnia longiremis, and Kellicottia longispina). In order to study the typology of the lake samples, the data were subjected to three types of statistical analyses: principal components analysis, single linkage, and complete linkage clustering. Five groups of lakes emerged from these analyses: types IV and V are located in the northeastern portion of the studied area, whereas types I and II were identified in the western portion, corresponding with the area occupied by the Tyrrell glacial sea. Type III fills an intermediate position. Types II, III, and V are smalt lakes. The characteristic zooplanktonic communities of each group are described, whereas the principal components and the components of the diversity are correlated with the environmental data.
The mismatch in distributions of vertebrates and the plants that they disperse