Modern climatic changes within the North-Western Black Sea region as a factor in the growth of ichthyopathological and invasive threats

The article presents the impact of climate warming in the North-Western Black Sea Coast region on the possible exacerbation of the ichthyopathological situation in the region's water bodies.The virulence of pathogens in the aquatic environment depends on several factors, including water flow, organic matter, and physical and chemical conditions.The most important factor is the temperature, which determines the development of helminths, fungal pathogens, viruses and affects the physiological and immune properties of fish.Climate warming in the region leads to an increase in critical water temperatures in the summer and autumn, which complicates the sanitary and epidemiological situation and causes disease outbreaks among the fish fauna during these periods of the year.According to the analysis of long-term observation data from the main monitoring stations in the North-Western Black Sea Coast region, stable manifestations of climate warming began to be observed here after 1988.The method made it possible to identify two main periods: before climate warming (from the beginning of instrumental observations until 1987) and the current (man-made) warming period -from 1988 to the present.In the first period, negative deviations of average annual air temperatures from the long-term norm were observed, ranging from -0.29 to -0.66 depending on the observating location.The period of modern warming is characterised by sharply positive deviations of average annual temperatures from the long-term norm, ranging from +0.6 to +1.2, indicating a stable increase in temperature from year to year.The average annual temperature in the region before climate warming was in the range of 9.7-10.3,after warming -11.0-12.0and in some years can reach 13.8C.An increase in water temperature above 20-25C increases the risk of epizootics in fish.In particular, due to climate warming and an increase in water temperatures during critical periods throughout the year, an increase in infectious, helminthic, invasive, fungal and bacterial diseases can be expected.Among the water bodies that, under the influence of the factor of increasing air and water temperatures, have conditions of increased ichthyopathological and invasive hazard are water bodies located within the lower reaches of the Danube (Izmail, Bilhorod-Dnistrovskyi districts of Odesa region) and water bodies in the southern part of Kherson region (Skadovsk, Henichesk districts, Syvash), as these regions are currently experiencing the greatest manifestation of climate warming.