Population regulation of the Chydoridae in Lake Itasca, Minnesota

Summary

The population dynamics of the chydorid Cladocera of Lake Itasca, Minnesota were monitored from 1973–1976. The chydorids typically exhibit low abundances in early spring which increase to an early summer population peak. Numbers then decline dramatically and remain very low throughout the summer and early fall. In order to determine the population control mechanisms, birth rates were estimated by the egg ratio technique of Edmondson and population decrease factors were evaluated experimentally.

We thank the staff of the Lake Itasca Biological Station for assistance and facilities during the study. This research was partially supported by funds from N. S. F. grant BMS 72–00079 to M. C. Whiteside.