The paper aims to present the results of the analysis of 20 macrozoobenthic samples collected in 2022 from the Romanian Black Sea shore. The depth of the sampling sites ranged between 12.3 m and 42 m, corresponding to the infralittoral and circalittoral zones. Qualitatively, 102 taxa of macrozoobenthos including 36 polychaetes, 25 crustaceans, 20 molluscs, 10 nemertians and 11 taxa representing other groups, were recorded. Polychaetes were predominantly abundant, representing 55.92% of density. Species such as Melinna palmata Grube, 1870, Heteromastus filiformis (Claparède, 1864) and Prionospio cirrifera Wirén, 1883 recorded the highest densities. Among crustaceans, the most abundant species were Ampelisca diadema (Costa, 1853), Phtisica marina Slabber, 1749 and Medicorophium runcicorne (Della Valle, 1893). The molluscs Abra prismatica (Montagu, 1808), Spisula subtruncata (da Costa, 1778) and Polititapes aureus (Gmelin, 1791) were considerably abundant as well. The average density of the benthic populations was 1571 indv/m2 . By far the highest densities were recorded at two sites located close to the Danube’s Sf. Gheorghe mouth, at depths of 12.3 m and 19.9 m, represented 18.40%, respectively 16.42% of the total average density. The other sites recorded densities not greater than 6%. The average biomass was 236.54 g/m2 and was dominated by molluscs (90.74%). Among stations, Sf. Gheorghe (40.1 m) recorded the highest biomass, representing 42.60% of the total average biomass.

"The composition and space-time distribution of mesozooplankton community from the Romanian Black Sea waters during 2020-2021 was analysed. Sampling was carried out during two expeditions (October 2020, September 2021), resulting a number of 133 samples. A total of 21 taxa were identified, the maximum being recorded in 2020, with nine taxa among copepods. Variations were observed between the two cruises, the mesozooplankton community being best represented in October 2020, when the highest density and biomass values were observed. The fodder component of the mesozooplankton community was dominant both in 2020 and 2021, Noctiluca scintillans (the nonfodder component) being less represented, with lower density and biomass values. From the fodder component, Copepoda represented the bulk of the community, with the highest values in 2020, followed by Cladocera with a maximum development in 2021. Branchiostoma lanceolatum larvae were identified in 3 stations in 2020 and in one station in 2021 at different sampling depths."

This paper focuses on the dynamics of four jellyfish species, Aurelia aurita, Beroe ovata, Mnemiopsis leidyi and Pleurobrachia pileus, from the Black Sea. The samples were taken in time of two expeditions in 2021 (May-June and August-September). Aurelia aurita species was dominant in terms of biomass due to its large size, The density of the species Pleurobrachia pileus recorded high values, in the north, but also between the isobaths of 40-80 m. The density of the species Mnemiopsis leidyi was higher in the southern and central area of the Romanian Black Sea. Because jellyfish feed on zooplankton organisms, the eggs and larvae of commercially important fish, high densities of jellyfish can produce direct decreases in the trophic chain by reducing the biomass of zooplankton, and fish eggs and larvae.