Phytoplankton of Lake Senezh in autumn 2024

A comprehensive study of the phytoplankton community of Lake Senezh (Moscow region) in the autumn of 2024 was conducted in order to assess the current state of the ecosystem and identify the relationship between abiotic factors and the development of algae. The work fills in the gaps in the study of the taxonomic structure and spatial distribution of phytoplankton in this reservoir. During the study, hydrobiological surveys were carried out at three stations located in the confluence zones of the Mazikha and Sister rivers, as well as in the dam area, using standard sampling and analysis techniques. The results showed the presence of 21 taxa of phytoplankton, including 6 species of diatoms (Bacillariophyta), 7 species of blue-green (Cyanophyta) and 8 species of green (Chlorophyta) algae. The absolute dominance of blue–green algae has been established (the average number is 438.89 million cells/l, the biomass is 13.66 mg/l), which is typical for eutrophic reservoirs. The lowest quantitative values (266.53 million cells/l, 5.4 mg/l) were recorded at station 3, where minimum temperature values (3.2 °C) and maximum concentrations of dissolved oxygen (12.8 mg/l) were noted. This indicates the predominant influence of the thermal regime on the development of phytoplankton. A comparative analysis with data from 2011-2012 revealed a positive trend – a decrease in the degree of eutrophication (the average biomass was 14.78 mg/l in 2024 versus 100-120 mg/l during the “flowering” period in 2011). However, the detected increase in biomass compared to 2012 indicates the need for continued monitoring. The results obtained are of great practical importance for the development of measures for biological reclamation of the reservoir, including recommendations for the introduction of the white carp. The research makes a significant contribution to the understanding of ecological processes in the reservoirs of central Russia and the development of strategies for their sustainable management.