Structure and seasonal dynamics of zooplankton in the Desnogorsk reservoir (Smolensk NPP cooling pond) anthropogenic thermal impact in 2025

The paper presents the results of a study on zooplankton in the Desnogorsk Reservoir (a cooling pond of the Smolensk NPP) during the 2025 growing season. Based on the average seasonal biomass (0,5 g/m3), the water body is classified as having low foraging capacity. A clear seasonal dynamic was revealed: maximum abundance was recorded in spring (222,6 × 103 ind./m 3 ) due to rotifers, while the peak biomass (0,67 g/m 3 ) occurred in summer, driven by the development of cladocerans in the riverine zone. Correlation and regression analyses showed that high summer temperatures (above 26 °C) act as a limiting factor. In the NPP impact zone, water overheating leads to community suppression and a transformation of trophic interactions with phytoplankton from grazing to competitive relationships. Principal component and cluster analyses confirmed the dominant role of the seasonal factor in structuring the community.