Determination Analysis in Ecosystems: Contingencies for Biotic and Abiotic Components

Relationships between physicochemical variables and between abundance of zooplankton species, as well as dependence of the species abundance on abiotic factors, were studied by determination analysis in the ecosystems of the Sura River and Surskoe Reservoir. Marker hydrochemical variables (BOD 5 and concen- tration of dissolved oxygen) were revealed; their oscillations indicate increases or decreases in concentration of most pollutants. A set of species with correlated abundance was recognized in the zooplankton community. The ecologically tolerable levels of the environmental factors providing for high abundance of zooplankton species were calculated.