LONG-TERM CHANGES OF COPEPODA (CRUSTACEA) ABUNDANCE AND BIOMASS IN THE DANUBE AND ODESA REGIONS OF THE BLACK SEA AS INDICATOR OF WATER QUALITY

Copepoda are the most important zooplanktonic group constituting the primary food for fish larvae and some fishes. Copepoda have the longest life cycles among the Black Sea mesozooplankton, so their biomass and percentage of total zooplankton biomass is greatly reduced by eutrophication. The percentage of Copepoda from the total biomass of zooplankton is a reliable indicator of the ecological status of the water bodies. For the Black Sea marine waters the indicator of “good” ecological status (GES) is the average annual biomass of Copepoda, which exceeds 45% of the total biomass of zooplankton. Changes of total biomass of zooplankton, biomass of Copepoda, the abundance and biomass of dominant species – Oithona davisae Ferrari F. D. & Orsi, 1984, Acartia (Acartiura) clausi Giesbrecht, 1889 and A. (Acanthacartia) tonsa Dana, 1849 in the Danube and Odesa marine regions from 1970 to 2019 were analysed. Also the ecological quality class in the Nort-Western part of Black sea by Copepoda indicators from 2004 to 2017 were established according to Water Framework Directive US. The total zooplankton biomass had been decreasing in Ukrainian waters and % of Copepoda from total zooplankton biomass was increasing. These tendencies shown a positive change in the forage base of commercial planktophagous fishes and ecological class status of the investigated aquatories. The abundance and biomass of O. davisae, A. clausi and A. tonsa were decreased from 2016 to 2019. The highest values of their metrics were in 2016 and the lowest rates observed in 2019. O. davisae, A. clausi and A. tonsa were the main components of copepods number and biomass. The Acartia species formed higher part of Copepoda biomass than O. davisae. The ecological state was “good” (GES) only in Danube-Dnieper coastal waters and Danube delta in 2004–2017 where Copepoda formed more than 45 % of total zooplankton biomass. In waters of Northwester Black Sea bays, shallow and deepwater shelfs the ecological state was “Bad” (notGES), the part of Copepoda was lower than 45 %.