Periphytic ciliates in littoral zone of three lakes of different trophic status

Periphytic ciliate communities were investigated in three lakes of different trophic status of the Leczynsko-Wlodawskie Lake District (Eastern Poland). Observations were made of the periphyton growing on glass-slides. Samples were taken from April to November 2000-2001. Once a month, four periphyton samples were collected in littoral zone. Seventy three ciliate taxa occurred in the studied lakes. The biggest number, 60 species, was found in eutrophic lake, a little less, 55 species, in mesotrophic lake and the least, 49 species, in dystrophic lake. The lowest density was observed in mesotrophic lake and it was 13 x 10(3) ind. m(-2), being a little higher in dystrophic lake-16 x 10(3) ind. m(-2), and tile higilest 20 x 10(3) ind. m(-2) in eutrophic lake. All of the studied lakes were generally dominated by ciliates belonging to the order Cyrtophorida (Chilodonella uncinato Ehrenberg 1983) constituted >30% of tile total numbers. In all lakes bacterivorous ciliates occurred in the highest numbers (>50%), while algivorous and histophagous - in the lowest (<5%). In the eutrophic and dystrophic lakes the proportion of omnivorous and predator), species was high. The number of significant correlations differed among lakes. In mesotrophic lake the correlation between ciliates abundance and total organic carbon was found. In eutrophic lake total number of ciliates was positively correlated with the conductivity TP and TOC. In dystrophic lake the correlations between ciliates abundance and abiotic parameters were not observed. In mesotrophic and dystrophic lakes the content of organic matter positively correlated with the biomass of ciliates, while in cutrophic lake conductivity showed positive correlation with their biomass.