Ichthyoplankton and trophic relations in the plankton communities inshore of the South-Western Crimea (Black Sea) during the summer season 2013

Abstract

Species composition and quantitative indicators of zoo- and ichthyoplankton feeding of fish larvae were studied inshore of the South-Western Crimea in the summer of 2013. There were 33 species of fish eggs and larvae from 24 families identified in ichthyoplankton. It was twice as large as it was in the 1990s. Inshore of Sevastopol in May 2013 the anchovy spawning was efficiently spawned due to favorable temperature of the sea water (+21 °C) and good food conditions. The largest number of summer-spawning species was recorded in June at the surface water temperature of +22.7 °C. Abundance of fish larvae in inshore region increased too, compared to this of the 2000s, due to their high survival rate resulting from improved food conditions. There was relatively high abundance of zooplankton and the predominance of a small-sized fraction mainly by juvenile stages of copepods. Low abundance of ctenophore Mnemiopsis leidyi and its slight impact on zooplankton were other factors that improved the food base of fish larvae.