Interannual Variability of Lipids and Fatty Acids in Azov Anchovy Engraulis encrasicolus maeoticus (Engraulidae) under Current Salinization of the Sea of Azov

Аннотация

The work examines the food supply of the Azov anchovy Engraulis encrasicolus maeoticus in 2006–2013, while the level of salinity of the Sea of Azov was rising from 9.3 to 12.6‰. The food supply was assessed based on the lipids and essential polyunsaturated fatty acids (eicosapentaenoic and docosahexaenoic) accumulated in the body of the anchovy at the end of the feeding stage (October–November). As salinization of the sea progressed, the level of the total lipids in the anchovy body increased from 15.5 to 18–18.7% owing to triacylglycerol content; absolute amounts of eicosapentaenoic and docosahexaenoic acids grew 1.9 and 2.6 times respectively (from 576 to 1091 and from 594 to 1540 mg/100 g of wet weight). Along with this, anchovy stock increased multifold, which equally indicates a significant improvement in food supply of the fish. Qualitative composition of the anchovy diet was found to shift towards the dominance of the Black Sea migrants and an increased share of the animal-source food in the intake. In addition, we discuss the correlation between the interannual variability in food supply of the anchovy in 2006–2013 and stock of its main trophic competitors in the Sea of Azov, namely, tyulka Clupeonella delicatula delicatula and ctenophore Mnemiopsis leidyi.