Interannual Population Dynamics of the Ctenophore Beroe ovata Bruguiere, 1789 at the Outer Shelf of Sevastopol Bay of the Black Sea

摘要

On the basis of the results of cruises and long-term monitoring at the outer shelf of Sevastopol Bay, the interannual dynamics of the state of the population of the alien ctenophore Beroe ovata in the Black Sea for 2000-2021 was analyzed. It was established that, in recent years, the ctenophore was found in plankton earlier than usual, the period of its active pelagic life increased to 7-8 months, and the body length in juveniles decreased from 40 to 20-25 mm. Three seasonal periods are distinguished, which, owing to their temperature conditions, were especially significant for the species: January-February, April-May, and July-August. The high temperature of seawater in July-August usually contributes to an increase in abundance and biomass of the ctenophore, as well as a decrease in the average size. The period of active life of B. ovata depends on the warming of the sea in May, as well as on the biomass of Pleurobrachia pileus. The early appearance of B. ovata leads to faster suppression of Mnemiopsis leidyi, preventing it from reaching a high abundance and biomass in summer.