Occurence of molluscs communities in a lowland dam reservoir colonized by Dreissena polymorpha [Pallas] [Sulejow Reservoir, Central Poland]

The work aimed at the analysis of the structure and abundance of mollusc communities and their connection with environmental factors, especially the influence of Dreissena polymorpha. Molluscs were collected at 21 sampling stations within the Sulejów Reservoir in July 1999 and 2000 using Ekman-Birge's grab and bottom dredge. Generally fauna of molluscs was dominated by D. polymorpha, however in the upper part of the reservoir relative abundance of this species was low. The effect of zebra mussel on malacocenoses resulted in significant differences in species richness and densities between the habitats where this mollusc occurred in lower and higher abundance.