EN
The abundance and species composition of ciliates were analysed in pelagic zone of two depression reservoirs: Nadrybie and Szczecin (Polesie Lubelskie, eastern Poland) from May to November 2002. Totally 21 ciliates species were found in Szczecin reservoir and 24 in Nadrybie reservoir. The mean abudance of ciliates was 31 ind. ml-1 in Szczecin reservoir and 26 ind. ml-1 in Nadrybie reservoir. Ciliates communities in both reservoirs were dominated by Scuticociliatida (Cinetochilum margaritaceum) and Peritrichida (Vorticella sp.). Densities and species composition of ciliates showed clearly changes. In both reservoirs the correlation between ciliates density and conductivity, pH, TP and TOC was found.