Long-term changes and spatial variability of mollusc communities in selected habitats within the dam reservoir [Wloclawek Reservoir, Vistula River, Central Poland]

The studies on long-term and spatial variability in dominance pattern and abundance of malacofauna in selected habitats of the Włocławek Reservoir (Central Poland) were made in relation to environmental factors. Abundant and relatively rich in species malacocenoses were dominated by Sphaerium corneum. Malacofauna of shallow biotopes was characterized by higher species richness and lower abundance than molluscs inhabiting the old river bed. Eutrophication, turbidity and transformation of bottom sediments are likely to be the most important factors influencing changes in malacocenoses.