Abstract
The values of Clark W-statistics, ∆-Shannon-Weaver, and an average individual mass of specimen were used to characterize the spatial distribution of zooplankton in the Kolsay lakes. With a relatively constant species composition, the interannual dynamics of the size and quantity variables of zooplankton testified to an increase in the eutrophication processes of three of the four Kolsay lakes. Interannual changes in the structure of the zooplankton community were mostly determined by the introduction of allochthonous species of fish, reduction of the water level, and enhancement of biogenic load due to recreational use of the lakes. The effect of very low concentrations of heavy metals on the dimensional variables of zooplankton can be connected with the oligotrophic status of Kolsaiskie lakes.