Features of the Distribution of Black Sea Ichthyoplankton in Conditions of Activation of Atmospheric Processes in the Summer Hydrological Season of 2021

Abstract

The article presents the species diversity, abundance, and distribution features of ichthyoplankton and fodder zooplankton in the northern Black Sea in summer 2021. The intensification of cyclonic activity over the Black Sea in June–July slowed the formation of summer-type thermal stratification in the studied water area. At the beginning of July, only 13 species of eggs and fish larvae were observed in ichthyoplankton of the Crimean Peninsula, and their average abundance was 29 and 2 ind./m², respectively. At the beginning of August, summer-type vertical thermal stratification off the coast of the Caucasus had already formed. The number of ichthyoplankton species increased to 20. Activation of atmospheric processes in June–July intensified the intraseasonal wind “pumping” of the upper layer of the sea. The Black Sea Rim Current transformed into a pronounced jet over the continental slope, oriented alongshore, partially extending to the shelf. This did not affect the spawning activity of mass fish species. The average abundance of eggs in the shelf and deep-water zone was about 160 ind./m², and the average abundance of larvae on the shelf was almost five times higher, 452 ind./m².