Dynamics of microbial communities under conditions of active economic activity in the water area of the North Caspian

Relevance. Microbial communities are important components of aquatic biocenoses of any reservoir. Possessing a wide range of adaptive capabilities, bacteriocenoses are able to quickly respond to changing environmental conditions, fully reflecting the functioning of the ecosystem of the reservoir under study. The state of a heterotrophic bacteriocenosis and the quality of natural waters can be assessed both by the total number of bacterioplankton and by the ratio of the number of its constituent bacterial groups. Methods. Standard microbiological research methods were used: the total number of bacteria was counted by epifluorescence microscopy, the number of ecological and physiological groups was counted by the method of limiting dilutions in liquid elective media. Results. The article presents the data on the dynamics of microbial communities under conditions of active economic activity in the waters of the Northern Caspian Sea in the area of the field named after. V. Filanovsky in 2023 are presented as part of environmental monitoring. Analysis of the seasonal dynamics of the state of heterotrophic bacterioplankton and bacteriobenthos revealed a change in the indicators under consideration in a seasonal aspect: their increase is observed in the fall, which is largely due to the processes of resuspension, the metabolic characteristics of the studied groups of heterotrophs, as well as the hydrological and temperature characteristics of the period research. The resulting warming of water masses, as well as the ongoing processes of mineralization of organic substances and the processes of self-purification of the studied reservoir in the autumn period ensured a more active development of bacteriocenosis in the autumn in the studied water area.