LAUSR

Interannual variations in species richness and quantitative parameters of macrozoobenthos in floodplain lakes of the Khoper Nature Reserve have been studied to reveal their dependence on flood regime and overgrowth by macrophytes. It has been shown that a particular species richness of macrozoobenthos is preserved for several years. Interannual variations in characteristics of lakes, particularly in the flood period, determine the changes in quantitative parameters of macrozoobenthos. The overgrowth rate of lakes by macrophytes does not exert an effect on species richness and quantitative parameters of macrozoobenthos, but determines its saprobiological structure. The flood period necessary for the formation of the most abundant communities of macrozoobenthos in the studied lakes is 30 days. Nevertheless, this is not the main factor determining its quantity in lakes constantly connected with the river by a channel. It is confirmed that drying or a sharp drop in water content of the river play the role of a trapping point and triggers ecosystem transformations in small water bodies.