EN
Psammon rotifers were investigated in two lakes of different trophy and degrees of pollution. The Plawniowice Duze Reservoir is mesotrophic, while the Dzierzno Duze Reservoir is highly eutrophic and polluted. Samples were collected from three zones on sandy beaches - one meter above the shoreline (eupsammon), at the shoreline (hygropsammon) and below the water level (hydropsammon). A larger number of rotifer species (28) was detected in the Plawniowice Duze Reservoir than in the Dzierzno Duze Reservoir (18). The species structure of the rotifer communities differed in the two reservoirs. While the density of eupsammic rotifers observed in both reservoirs was high, significant differences were noted in the abundance of them. The dominant species were Cephalodella gibba, Cephalodella catellina and Lecane closterocerca.