Abstract

  An overview of current status of microbial research in the Great Lakes consisting of structural, toxicological, and cytological aspects is presented. A variety of techniques for the identification and enumeration of food-web parameters such as bacteria, autotrophic picoplankton, heterotrophic nanoflagellates, ciliates, and various size fractions of phytoplankton have been evaluated. An extensive lakewide survey of the Great Lakes conducted in 1991 indicated high bacterial abundance in Lake Erie and the Detroit River, and lowest numbers in the oligotrophic Georgian Bay and Lake Superior. The autotrophic picoplankton were lowest in the contaminated ecosystems of the Detroit River, St. Clair River, and Lake St. Clair This persistent sensitivity of the autotrophic picoplankton to environmental perturbation make them ideal candidates as early warning indicators of ecosystem health. This is the first time that such a comprehensive strategy has been attempted encompassing all important components of the microbial food-web in the Great Lakes. These results clearly demonstrate the significance and potential of microbes in providing a multi-trophic, dynamic, and holistic picture of the aquatic ecosystems. Furthermore, the necessity of monitoring microbial food-web parameters is recommended and emphasized.

Keywords: bacteria, picoplankton, heterotrophic nanoflagellates, ciliates, nanoplankton, food                  web