Phytoplankton Life as an Indicator of the Reservoir Ecosystem State under the Influence of Thermal Pollution from the Electrical Power Plant in European North

Abstract: The species composition, the structure of phytoplankton communities, hydrochemical parameters in the artificial cooling reservoir of one of the largest thermal power plants (TPP) in the north-east of Europe in the Pechora River basin, Komi Republic were studied in the ice-open period in June and August. Altogether 81 species of algae and cyanobacteria was revealed with the last one predominated. Among cyanobacteria and algae (Bacillariophyta, Chlorophyta), indicators of water quality were found. Assessment of water quality according to the species composition and abundance of indicator phytoplankton species showed that the waters of the Pechorskoe Reservoir can be at-tributed to the III class of water quality, beta-mesosaprobic self-purification zone, with water quality of satisfactory purity, retaining the ability to self-purify. An increase in the diversity of plankton communities and high values of their abundance and biomass under the influence of the warming effect of TPP water outlet were noted and revealed its spatial distribution over the reservoir surface. The plankton of the northern reservoir under the influence of warm waters indicates a slight in-crease in the trophic status of the studied water body, which is also confirmed by the data of hydrochemical analysis. Ecological mapping for the chemical and biological variables as well as pollution indices over the water area of the reservoir was carried out. The results obtained can be used to make forecasts of changes in the phototrophic biota of small northern water bodies under the conditions of climate change.