Plankton ciliates of the Saratov reservoir in the summer-autumn period of 2023

The spatial distribution of ciliates in the riverbed of the Saratov reservoir was studied in July-September of 2023. About 70 species of ciliates have been identified, of which 88% of the species were registered in the central part of the reservoir. The quantitative characteristics of ciliates community in the Saratov reservoir were generally quite low: the range of variation in the number was 20-976 thousand cells /m3, biomass - 0.12-49.68 mg/m3. There was a heterogeneity in the distribution of characteristics of the ciliates community in the water area of the reservoir. Thus, the maximum number and biomass of ciliates were recorded in two central reaches (Syzransky and Khvalynsky), due to the fact that large territories of the floodplain terrace, many overgrown shallow waters were formed here as a result of flooding of the Volga floodplain, estuaries of tributaries. The minimum characteristics were on the upper “river” section of the reservoir. In the trophic structure, algovoures and nonselective omnivorous species formed the basis of the population in the reservoir as a whole. Predators with their predominance in the ciliate community in the central reaches formed the basis of the biomass, which indicates a rather diverse, complexly structured community in this part of the reservoir; this indicated a diverse, complexly structured community in this part of the reservoir.