DIFFERENTIATION OF PERIPHYTON AND PHYTOPLANKTON ASSEMBLAGES IN ANTHROPOGENICALLY TRANSFORMED CONDITIONS OF THE LITTORAL ZONE IN A SHALLOW URBAN LAKE (LAKE JEZIORAK MAŁY, POLAND)

Abstract

This study of periphyton (periphyton in separator pipes, epilithon and epiphyton) and phytoplankton (pelagial) assemblage differentiation was conducted in Lake Jeziorak May within an anthropogenically transformed littoral zone. Analysis was conducted on the differences in abundance and biomass of these assemblages in relationship to the physico-chemical water parameters, species' similarity, diversity and environmental requirement s of these assemblages, from April to October of 1997-2003 and in 2005. The periphyton in the pipes and epilithon were foun d to be the most similar assemblages . Despite similar substratum characteristics, changes in the physico-chemical water parameters, and especially those in PO 4, Si and Cl, were found to affect these assemblages ' development. This was supported by correlations between the char acteristic species and nutrients. While the growth of epiphyton was mainly related to changes in calcium and nitrogen concentration, phytoplankton depended more on conductivity, pH and Fe. The presence of se ven algal groups with different environmental requirements indicated considerable differentiation of the studied assemblages resulting from anthropogenic transformation of this littoral zone. The installation of separators and a lso stone accumulations in this zone contributed to the creat ion of new habitats for periphytic algae which utilized the common pool of nutrients. It may therefore have indirectly influenced phytoplankton dominated by cyanobacteria.