The community-wide trophic cascade due to collapsed fish stocks and population outburst of invasive predators after the early 1990s resulted in different pelagic and benthic food web structures in the Black Sea. The northeastern region assumed their most simplified forms characterized by increasing mesozooplankton and polychaete biomass. The ecological degradation is more severe in the northwestern part, whereas the southern basin maintains an anchovy fishery under relatively weak gelatinous predation.

"The paper aims to develop and test a semi-quantitative method that generates scenarios for the zooplankton community development under salinity and nutrients fluctuations. First, we identified the relationships between the mesozooplankton component and the environmental factors by analyzing data (N=2566) collected within the warm season (May-September) of a decade (2008-2018). The biotic and abiotic parameters were investigated at 37 stations within the monitoring network of the Romanian Black Sea waters, covering all three marine reporting units (waters with variable salinity, coastal and marine) according to Marine Strategy Framework Directive (MSFD). We identified 32 mesozooplankton species belonging to ten taxonomic classes, copepods representing the bulk of the community. In waters with variable salinity and coastal waters, the fodder component of the mesozooplanktonic community was dominant, while in marine waters the nonfodder component was better and exclusively represented by Noctiluca scintillans. Physicochemical parameters that showed significant correlations with the mesozooplankton species were S (salinity) and nutrients - NO2- (nitrite), NO3-(nitrate), PO43-(phosphate) and NH4+(ammonium). The number of species significantly correlated with the physicochemical parameters showed variations generally correlated with the increasing salinity gradient: in waters with variable salinity nine species being correlated, in coastal waters ten species, and in marine waters five species. Key-Words: mesozooplankton, fodder, nonfodder, correlations, physicochemical "

"Pelagic fish species can be affected by a series of infectious and parasitic diseases. The data used for this study are represented by the biological material collected between 2018 and 2019, from trap nets along the Romanian Black Sea waters. To establish the degree of parasitism, the following species of pelagic fish were studied: Sprattus spratus -sprat, Engraulis encrasicholus - anchovy and Trachurus mediterraneus- horse mackerel. Four species of endoparasites were identified, belonging to nematodes, as follows: Hysterothylacium aduncum, Contracaecum sp., Porrocaecumsp. and Anisakis sp. The parasites, especially found as larvae, more in free state and less trapped in the internal organs, infested the abdominal cavity, leading to degenerations, atrophies and reduction of the fish functions. The intensity of the parasitism infestation could be lethal, the size of the stocks being severely damaged. At the analysed fish species, the infestation degree was under 20 parasites per host, a low number of species recording the maximum value of 40 parasites per host. The parasites tend to accumulate with the increase of the fish's size, young stages being less affected. Key-Words: parasites, fish, nematodes, intensity, infestation degree "

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.