Quantitative and qualitative changes of the phytoplankton in heated Konin lakes

Abstract

Artificial water heating in Konin lakes and its intensive exchange between these lakes were the main factors affecting the phytoplankton densities and composition in the 60-ies and 70-ies. Increase of water temperature stimulated phytoplankton development, with diatoms as the dominant, this being especially noticeable in the first ten years of functioning of the cooling system. On the other hand, low water retention restricted algae development, so that phytoplankton abundance decreased gradually while its taxonomic diversity increased since the begining of the 70-ies. Another increase of total biomass of the algae, with blue-greens dominating in summer, was observed in the second half of the 80-ies. It was due to an increase of lake fertility which induced new trend in the long-term phytoplankton succession in Konin lakes.