Impact of habitat quality on the microbial and immune status of captive marine mammals

The aim of research was to study the effect of sanitary and microbiological parameters of water on the microbial and immune status of marine mammals kept in the marine biology center. The studies were carried out at the Center for Oceanography and Marine Biology; Department of Microbiology, Epizootology and Virology of the Kuban State Agrarian University, and the Kropotkin Regional Veterinary Laboratory in 2022–2024. The chemical and microbiological parameters of water quality in marine mammal tanks were studied. Water samples were collected from January to August. The blood of South American sea lions was determined for immunoglobulins of classes A, G, and M; the level of phagocytosis was assessed. The fecal samples were used to determine the quantitative content of lacto and bifidobacteria; gramnegative coliform bacteria (OKB, TKB), coccal microflora, and yeastlike fungi. Monitoring of the chemical composition of the water in the sea lion pool showed that the concentration of nitrates varied significantly at different sampling times. Regardless of the time of year, the concentration of nitrites in the water consistently exceeded 3.0 mg/dm3 (the standard indicator), and the concentration of ammonium nitrogen exceeded the standard by 1.2–2.6 times in 87.5 % of samples. The total number of microorganisms (TMC) in the water in the winter months did not exceed the established standard, in spring and summer the level was 2 to 6 times higher than the established standard. In the summer, total coliform bacteria (TCB), the presence of which is not allowed, were detected in the studied water samples. Representatives of the intestinal normal flora Lactobacillus and Bifidobacterium were present in the microbiome in quantities significantly lower than the average for this species of animals. The number of lactobacilli in female 2 was 1.58 times lower than the standard and averaged 3.80 lg CFU/g, and in female 1 – 1.26 times lower than the standard (4.75 lg CFU/g). Noncompliance of the sanitary and microbiological parameters of water in pools for marine mammals with the standards leads to purulentinflammatory processes, dysbacteriosis, suppression of the functional activity of the immune system.