Feed value and seasonal dynamics of zooplankton in cooling reservoirs of Shaturskaya SRPP as a basis for assessing the feeding capacity of Lakes Svyatoe and Muromskoye (Moscow region)

During the 2025 growing season, a comprehensive fisheries assessment of the zooplankton food supply was conducted for Lakes Svyatoye and Muromskoye, which serve as cooling reservoirs for the Shaturskaya SRPP (Moscow Region). The study, spanning spring, summer, and autumn, established that the seasonal mean zooplankton biomass in Lake Muromskoye was 2.30 g/m³, classifying it as a water body with an above-average food supply. In Lake Svyatoye, this value was recorded at 1.91 g/m³, corresponding to the category of moderate food supply. A pronounced seasonal succession of plankton communities was revealed: the spring peak (reaching 5.82 g/m³ in Lake Muromskoye) is driven by the mass development of cladocerans, primarily Bosmina longirostris. This creates a critical “feeding window” for the larvae and fingerlings of pikeperch and bream. However, during the summer-autumn period, a degradation of the food base was observed, characterized by the replacement of cladocerans with less caloric and more mobile copepods. It was established that the key limiting factors are extreme water heating (above 28-30 °C) and intensive predation pressure from predatory zooplankton (Leptodora kindtii). Saprobiological analysis using the Pantle-Buck method showed saprobity indices of 1.58 for Lake Muromskoye and 1.68 for Lake Svyatoye, corresponding to the β-mesosaprobic zone and Class III water quality. This indicates a moderate anthropogenic impact and no restrictions for fisheries use. The results provide a scientific basis for the feeding capacity of the lakes and can be applied in planning fish stocking volumes, as well as optimizing the operation of cooling reservoirs to maintain their biological productivity.