In Lake Onega zooplankton is considered as a convenient and reliable indicator of the state of the lake ecosystem. As a formal basis for the consolidation of the accumulated information on the biota of Lake Onega, it is proposed to create an expert system using zooplankton as a prototype of an intelligent computer environment on all biotic components. In this context, it is proposed to review the organization of monitoring the state of zooplankton to increase the number of samples taken and to expand the geography of sampling as well as to simplify and computerize the sample analysis.