Phytoplankton of the Ukrainian Polissia River Ecosystems

The peculiarities of the phytoplankton structures of the main Polissia rivers - Pripyat and Teteriv - have been established. The main trends in the transformation of the autotrophic network of Polissia rivers have been uncovered. In total, between 2003-2020, 621 species of algae were identified, represented by 660 intraspecific taxa belonging to 217 genera, 81 families, 35 orders, 14 classes, and 8 divisions. Fifty-one specific and intraspecific taxa were found to be new to the Ukrainian Polissia. The appearance of species new to the region is largely due to changes in the hydrological and hydrochemical regimes of watercourses associated with regulation, land reclamation, anthropogenic pollution, and climate changes. The thoroughness and purposefulness of this study by covering a many territories and watercourses including various physical and geographical regions in the Ukrainian Polissia. The main abiotic parameters that cause changes in the structural indicators of phytoplankton in the studied watercourses have been determined. It was established that the relationship between algofloristic indicators and environmental factors is largely determined by the content of biogens. A strong inverse connection was found between the number of algae species and water color, as well as a weak correlation with temperature. A bioindicative analysis of the species composition of phytoplankton of river ecosystems was carried out, and the quality of their waters was assessed. In the watercourses of the region, the predominance of saprobity indicators, which correspond to the III class of water quality, was determined.