Bioindicative value of taxonomic and structural indicators of plankton algae communities for assessing a point source of anthropogenic impact

Phytoplankton studies were carried out in a small river (the Usa River, the Kuibyshev Reservoir basin) in the area affected by a point source of pollution. Comparative analysis revealed a change in the structure of phytoplankton in the wastewater discharge zone of the village of Shigony (Samara region). An increase in the saprobity index, a variety of species-indicators of an increased degree of saprobity, as well as an increase in the role of small-celled species in the community in this area are shown. At the same time, the species diversity at the discharge site and downstream is comparable to other parts of the river. The saprobity indices are within the β-mesosaprobic zone, quality class III (moderate pollution). In general, the impact of wastewater during the study period is localized at the place of discharge.