Seasonal Dynamics of Microbiological Indices of Freshwater Fishes of the Khadzhybey Estuary

The paper deals with seasonal fluctuations of the main microbiological indicators in samples of the freshwater fishes (common carp and round goby) from the Khadzhybey estuary. Attention was focused on use of live fishes as bioindicator of pollution of the aquatic environment, as sanitary condition of the reservoir is unsatisfactory. Besides, high microbial pollution of the reservoir can pose a threat to public health. It was found that during 2021-2022, the values of total bacterial contamination in fish samples were almost constant throughout the year, with a clear tendency to increase in summer, with a gradual decrease in the autumn-winter period due to self-purification processes in the reservoir. In 2023, a significant increase in parameters was detected in summer (June), which coincided with catastrophe of the Kakhovka HPS, but then total bacterial contamination stabilized. No Escherichia coli was detected in any sample, indicating the absence of fecal contamination of water in the Khadzhybey estuary and satisfactory operation of water treatment facilities. The results demonstrate that over periods of increased water temperature, special attention should be paid to conducting veterinary and sanitary inspection of fresh fish, as it can become a source of food-borne infections and toxicoinfections.