In recent years, hydrocarbon exploration and production operations have intensified in the Black Sea. Alongside growth in exploration and production activities, the influence of chemical usage across multiple industrial sectors within the Black Sea environment has become increasingly interesting. The aim of this research was to define a protocol for determining the acute toxicity of chemicals using the golden grey mullet, Chelon auratus (Risso, 1810), a native pelagic fish species of the Black Sea. Juvenile golden grey mullets were exposed for 96 h, under semi-static conditions, to dilutions of the reference toxicant 3,5-Dichlorophenol. Results from three reference toxicity tests (LC50 = 1.25 mg/L, 1.739 mg/L, and 1.409 mg/L) indicated that C. auratus is of moderate sensitivity when compared to literature values from EPAs Ecotox database. The protocol described within is intended to ensure Black Sea native organisms are represented by standard hazard assessment practices.

"The assessment of contaminants in biota is important, not only for biomonitoring of the marine pollution, but also in case of biota used for human consumption there are further implications with respect to public health reasons. Since data on this topic are rather limited in the Black Sea region, activities carried out in the framework of CBC Project “Assessing the vulnerability of the Black Sea marine ecosystem to human pressures” (ANEMONE) contributed at filling knowledge gaps identified for the region. Thus, new data on chemical contamination (heavy metals, polycyclic aromatic hydrocarbons, organochlorinated pesticides, polychlorinated biphenyls) of marine organisms (mussels, veined rapa whelk, pelagic and demersal fish), collected in 2019 during specific pilot studies in the selected study areas (open sea, and coastal – in front of river mouths, hot-spots) from Ukraine, Romania, Bulgaria and Turkey were obtained. The HELCOM integrated hazardous substances assessment tool (CHASE) developed by NIVA Denmark was tested in the Black Sea with contaminants in biota data set and the overall scores evinced sub-regional differences in the status results, with worse status predominating in the north-western part of the Black Sea (rivers influenced coastal areas and hotspots) and better status in the open sea area and in the southern part of the Black Sea. Across the investigated biota samples, the CHASE test assessment showed a range of status results from bad to high, almost half (46%) of biota samples being „unaffected by hazardous substances” state (good and high status), whereas the remaining 54 % of biota samples are „affected by hazardous substances” state (bad, poor and moderate). Key-Words: Black Sea, biota, heavy metals, organic pollutants, CHASE. "

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The use of living organisms to provide information on the quality of aquatic environments is now a widely accepted methodology for assessing contaminant bioavailability. Molluscs have developed tolerance mechanisms towards environmental stressors and can accumulate a large range of contaminants. The assessment of marine environment quality was based on heavy metals (HM), persistent organic pollutants (organochlorine pesticides – OCPs and polychlorinated biphenyls - PCBs) and polynuclear aromatic hydrocarbons (PAHs) analysis in Mytilus galloprovincialis, Rapana venosa, Anadara kagoshimensis species sampled during 2016 - 2020 along Romanian Black Sea coast. Toxic metals (cadmium, lead) had bioaccumulation levels below threshold values in most molluscs samples investigated. Cadmium registered few values (15%) surpassing maximum admissible levels, in all three species. Data evaluation demonstrated the maintenance of a high level of concentrations of persistent organic pollutants in the mollusc tissue, but also of the exceedances of the values that characterize the good ecological status of these compounds. Polynuclear aromatic hydrocarbons showed a declining trend and no exceeding of the maximum allowed limit for benzo[a]pyrene was recorded in the last years. In consequence, the overview assessment based on “OneOutAllOut” (OOAO) approach, considering all groups of substances, indicates a bad chemical status for this period.

The lysosomal membrane stability (LMS) of hemocytes in wild mussels (Mytilus galloprovincialis) as a biomarker of cellular stress for chemical pollution was tested by neutral red retention time (NRRT) assays. To assess the environmental contamination in the study area, seawater quality and pollutant bioaccumulation throughout the soft tissue of mussels were investigated. The samples were collected in July 2022 at four sites on the Romanian Black Sea coast considered to be differently affected by contamination. To support the suitability of LMS as a biomarker of contaminant-induced stress, the contaminant body burdens of the mussels were compared with the NRRT values. The results showed a significantly reduced NRRT in all investigated locations, particularly in port areas (mean retention time between 11 and 14 min). The elevated bioaccumulation of organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs) and low NRRTs were observed at the most contaminated sites (i.e., ports). The low lysosomal stability reflected stress and damage in the hemocytes of mussels and could be related to the body burdens of contaminants. LMS is an effective indicator of health status in mussels and could be considered a sensitive biomarker of cellular stress induced by contaminant exposure.