The state of zooplankton in the open coastal waters of Sevastopol (Black Sea) in 2009 - 2011

The state of zooplankton community, its seasonal and interannual dynamics were studied in 2009-2011 in open coastal waters of the Black sea near Sevastopol. Mean values of mesoplankton in 2009, 2010 and 2011 were not significantly different (3703, 2967 and 3315 ind. m -3 , respectively), in the plankton were dominated pelagic Copepoda ( P. parvus, A. clausi, P. elongatus ), but the contribution of individual species and the ecological complexes in the total zooplankton's number in these years was different. In 2009, the eurythermic species contributed up to 57% in the total abundance, cold- and warmwater species to 21 - 22%. In 2010, the contribution of eurythermic species increased to 67%, and coldwater species decreased to 8% of the total abundance. This year number of Bivalvia larvae was the highest during the study period (535 ind. m -3 ). In 2011 the contribution of coldwater species has increased to 35%, the number of warmwater species and their contribution to the total number dropped to 13%. Mean abundance of recent invader in the Black sea O. davisae in open coastal waters has increased during these years from units to 211 ind. m -3 ; in September 2010 its number reached a maximum 1406 ind. m -3 . Mean number of Noctiluca scintillans slightly decreased from 596 ind. m -3 in 2009 to 430 ind. m -3 in 2011. The seasonal dynamic of mesoplankton's abundance were characterized by peaks in the spring months (March - May) and in September. Noted that in 2009-2011, the summer decline of abundance was not as fatal as in the late 90's - early 2000's, and many species are not been affected