Characteristics of the ecological state of different types of reservoirs in the Samara region in 2023

The article presents the results of a study of 16 reservoirs of the Samara region located in the floodplains of the rivers B. Kinel, Volga, Samara and Sok and on the floodplain terrace near Tolyatti; the Dam and Novodevichy ples of the Kuibyshev reservoir, Usinsky, Cheremshansky and Suskan bays of the Kuibyshev reservoir, as well as the Usa river. In the spring and autumn period of 2023 in the studied reservoirs, relatively low water transparency was observed (0.9±0.7 m), with the highest seasonal average transparency recorded at the stations of the Kuibyshev reservoir of 1.2±0.7 m and the minimum in floodplain lakes (0.4±0.3 m). Bottom sediments are mainly represented by gray silts and fine-grained sands. The water column in most reservoirs was well aerated, the pH of the water was alkaline. The maximum water heating in 2023 was observed in July-August, when the temperature of the surface water layer could reach 30 °C. The concentration of chlorophyll «a» in the studied samples varied from 4.2 to 982.6 micrograms/l, and, judging by the ratio of chlorophylls, cyanobacteria prevailed in most samples in phytoplankton, and the development of eukaryotic algae was relatively weak. According to all indicators, in the spring-autumn period of 2023, the studied reservoirs of the Samara region were highly productive, and most of the floodplain lakes were hypertrophic. The analysis of the ratio of trophic status indices (TSIch /TSIp and TSIchl/TSIs) indicates that the development of phytoplankton by phosphorus in the studied reservoirs in 2023 is limited.