Study of scyphozoans Rhizostoma pulmo (Macri, 1778) washing up at Yasenskaya Spit of the Sea of Azov in September 2024

The article presents the results of studies of the washing up of scyphoid jellyfish Rhizostoma pulmo (Macri, 1778) on the western coast of the Yasenskaya Spit of the Sea of Azov in September 2024, and presents data on the number of specimens and biomass of beached jellyfish. Rhizostomapulmo is a species with a fluctuating habitat that migrates into the Sea of Azov from the Black Sea every spring. The total number of jellyfish washed up on the studied coast of the Yasenskaya Spit was 29500 individuals, and the total biomass was 36.74 tons. The average weight of a jellyfish was 1245.3 g. The great increase in numbers of R. pulmo in the Yasenskaya Spit could be due to the seasonal cycle of formation of temporary populations of this scyphoid jellyfish. In turn, the mass jellyfish washup on the coast of the spit is possibly associated with a decrease in the water temperature of the Sea of Azov. The obtained data could be used as supplementary information on the development of R. pulmo in the Sea of Azov and help in tracking structural changes in the plankton communities.