Seasonal distribution of the Black Sea ichthyoplankton near the Crimean Peninsula

Pattern of species composition and spatial distribution of the Black Sea ichthyoplankton in open waters near the Crimean Peninsula in different seasons of the year are based on the studies of materials collected during eight expeditions of the Research Vessel (R/V) ”Professor Vodyanitsky” from 2011 to 2016. We noted an increase in abundance and species diversity of ichthyoplankton during the spawning season, indicating positive changes in the plankton community of the Black Sea. Favourable temperature conditions for embryonic and postembryonic development as well as rich nutrient items contributed to the spawning season prolongation of the mass fish species of the Black Sea in recent years. In previous years, larvae of the thermophilic species Engraulis encrasicolus, dominating in summer ichthyoplankton species, were collected from June to September, but in recent years, they have begun to appear from May to October. Intensive spawning of the temperate-water species Sprattus sprattus dominating in the winter ichthyoplankton, has been observed in November, at the end of the autumn hydrological season, while its larvae are detected all year round. Prolongation of the productive spawning of thermophilic and temperate-water fish species results in the simultaneous appearance of their larvae in the sea. An increased population of short-cycle species facilitates the appearance of new species of temperate-water Mediterranean predators, namely Trisopterus luscus and Molva macrophthalma. Their eggs and larvae are detected in the ichthyoplankton, indicating favourable conditions for their spawning and the survival of the early larval stages