To many fishes, including commercially valuable species, metazoan microzooplankton (MMZP) are the essential prey ensuring survival of their larvae and juveniles. For the Black Sea dependence of the variability of MMZP abundance and structure on hydroclimatic factors (seawater temperature, wind force and direction, etc.) in the coastal area was not earlier studied over as short periods of time as days to weeks; hence this investigation is of high relevance. Samples of MMZP were collected daily in the mouth of Sevastopol Bay and the adjoining open-sea area from 13 May to 21 June 2013, the period when the quantity of MMZP began growing (spring-summer increase). The samples were taken from the sea surface by a 10 l plastic sampler, condensed in the laboratory by reverse filtration and processed in a Bogorov chamber under the microscope MBS-9. Increased crustacean fraction in which copepods dominated suggested growing abundance of the zooplankton with warming of the sea. This main, temperature-dependent, trend was modulated by short-term changes in the force and direction of wind launching quantitative and qualitative re-distribution of MMZP in the surface layer. Different behavioral responses the plankters showed to the wind-induced water turbulence can be a part of the re-distribution machinery. Contributors to the species diversity were largely the naupliar and early copepodid stages of genera Acartia, Oithona, Paracalanus, Centropages, the nauplii and copepodites of Harpacticoida, bivalve and gastropod veligers, larvae of the tunicate Oikopleura dioica, the nauplii of barnacles, and the larvae of polychaetes. The zooplankton assemblage structure changed in two phases: one, with moderately high values of species diversity index, was prior to, and the other, with low estimates, during the outbreak of the invasive copepod Oithona davisae.
New record of the planktonic copepod Oithona davisae Ferrari and Orsi in the Black Sea with notes on the identity of “Oithona brevicornis”
