Variability of hydrometeorological situation during fish kill events in the summer seasons of 2010–2018 in the Sea of Azov

Hydrometeorological situations during the fish kill events that took place in the Belosaray, Obitochny and Kazantip Bays in the summer seasons of 2010–2018 have been analyzed. Average monthly background water and air temperatures and wind velocity are considered, as well as their average daily values before, during and after a fish kill event. It is shown that background characteristics of water temperature and wind velocity influenced the development of a fish kill event more directly and definitely than air temperature, which influence was only indirect. In the majority of cases, hydrometeorological situation, leading to fish kill event, developed according to the typical pattern with increasing air and water temperature and decreasing wind activity. In the northern bays, the Belosaray and Obitochny Bays, fish kill events were recorded during the first half of summer season, and in the southern bay, the Kazantip Bay, they occurred in the second half of it. Since 2012, due to significant decrease in vertical thermohaline stability and increase in water homogeneity, no significant fish kill events were recorded under various temperature and wind conditions. Satellite imaging of sea surface temperature confirmed typical course of fish kill event development: the temperature increased in the pre-event period and then, after the event, stayed high in the southern bays and decreased in the northern ones.