Studies of mezozooplankton in the Zmiinyi Island coastal waters in 2016-2017

Purpose. To study the state of mezozooplankton in the Zmiinyi Island coastal waters in 2016-2017. Methods. Standard methods of mezozooplankton sampling, determination, number and biomass assessment. Results. Based on the data received, analysis of biodiversity and structural characteristics of mezozooplankton in the Zmiinyi Island coastal waters has been made. Taxonomic composition, number and biomass have been determined for each species; dynamics of number and biomass presented season by season. Marine environment quality assessment has been performed on the metrics of mezozooplankton. Conclusions. Altogether 32 taxa of 9 main mezozooplankton groups were identified in 2016-2017. It was shown that the dominating groups were Copepoda, Rotatoria, Protozoa, Cladocera and Harpacticoida. Shannon’s biodiversity index of mezozooplankton varied from 0.41 (20.06.2016) to 3.29 (24.07.2016) with average values 2.32 in 2016 and 1.64 in 2017. Mezozooplankton number and biomass varied in 2016-2017 within broad limits from 645 to 55829 ind/m³ and 1.385 to 2597.248 mg/m³ respectively (with average values 10129 ind/m³ and 154.82 mg/m³ in the period IV-XII, 2016 and 21563 ind/m³ and 466.30 mg/m³ in the period IV-VI, 2017). Water quality in the coastal waters of the Zmiinyi Island on the state of mezozooplankton was «Bad» in 18 cases out of 68 (26.4%) and was assessed in general as «Poor». On total mezozooplankton biomass the state was assessed as «Poor» and «Bad» (68.2%). «Good» (10.6%) and «High» (9.1%) quality was found in 19.7% of cases, which evidenced unsatisfactory state of mezozooplankton – the main component of food reserve for pelagic larvae and pelagic species of the Black Sea fish.