Summer ichthyoplankton assemblages and their environmental drivers in the Sinop Peninsula, Southern Central Black Sea

This study examines the composition and spatial distribution of ichthyoplankton assemblages in the central southern Black Sea, with a focus on the Sinop Peninsula. Ichthyoplankton samples were collected in June 2023 from 17 stations, and a total of 17 taxa belonging to 13 families were identified. Eggs of Engraulis encrasicolus, Merlangius merlangus, and Trachurus mediterraneus were the most abundant among ichthyoplankton, while larvae of Gobius niger and Diplodus annularis were dominant. The Shannon-Weaver index (H ') varied notably among stations, peaking at 2.32 in the easternmost site. Multivariate analyses (DistLM, dbRDA) revealed significant spatial differentiation in community structure, which was primarily associated with gradients in salinity, surface current velocity, and temperature. Environmental gradients are primary determinants of ichthyoplankton distribution, and mesoscale oceanographic processes significantly influence coastal ecosystem structure. Spatial segregation of spawning habitats, particularly between anchovy and horse mackerel, reflects distinct speciesspecific responses to salinity and current velocity in the Black Sea. This study provides a comprehensive description of the structure of the ichthyoplankton assemblages during the post-rainfall period, thereby establishing an important foundation for assessing the potential impacts of short-term meteorological disturbances on sensitive marine ecosystems.