LAUSR

Abstract — The paper presents characteristics of the species composition, spatial distribution, and trophic interactions of ichthyoplankton and zooplankton in the spring–summer period 2017 dependent on intensity of the warming-up of the upper sea layer against the background of transition in a system of the surface currents from the winter-to summer-type of the circulation. In April–May, successful spawning of temperate-water fish species was prolonged due to low values of the sea surface temperature (8–9°С) on the shelf of Crimean Peninsula between Kerch Strait and the cape Sarych. The maximum abundance of Sprattus sprattus eggs was 162.8 egg/m 2 and larvae –116 ind/m 2 . Warm-water species occurred only in the western sector from Herakleian Peninsula to the Cape Tarkhankut, where the water temperature was at its maximum and peaked at 14–15°С. In June–July the delayed summer hydrological season hampered the warming-up of the upper quasi-homogenous layer, which thickness varied from 1–5 to 10–15 m. Notwithstanding the large number of species in the ichthyoplankton, maximum abundance did not exceed 50 egg/m 2 and 14 ind/m 2 for larvae. The proportion of larvae of temperate-water fish species averaged 32% and reached 40% in deep water areas. Juvenile stages of copepods of the cold-water complex were dominant in the larval fish diet both in the spring and summer seasons.