Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which includes oxidative stress, modulation of antioxidant responses, activation of detoxification systems, DNA damage, inflammation, apoptosis, neuroendocrine disruption, and ultimately, cellular energy imbalance. In addition to established pathways, the review highlights recent advances in mechanistic understanding and biomarker development, including cellular stress responses, epigenetic regulation, metal homeostasis mechanisms, and novel molecular indicators. These mechanisms support the development of an integrated biomarker framework that combines classical indicators (e.g., antioxidant enzymes, metallothionein) with next-generation endpoints (e.g., miRNA profiles, gene-level responses of metal transporters or stress chaperones, epigenetic alterations). The interpretation of biomarker responses requires consideration of the exposure context, environmental variables, and physiological status to ensure accurate assessment of sublethal toxicity in field settings. By bridging mechanistic understanding with biomonitoring relevance, this review provides a comprehensive foundation for advancing molecular tools in pollution monitoring and risk assessment. Special emphasis is placed on biomarkers specific to heavy metal exposure, enhancing their diagnostic value relative to general stress indicators.

The widespread use of Tebuconazole-based fungicides in phytosanitary treatments on a wide range of crops, on the one hand, and the lack of official reports on the amount of fungicide residues in nearby water basins, on the other hand, may lead to uncontrolled and hazardous contamination of water sources used by the resident population, and to serious effects on the environment and public health. Our study explores the acute toxicological risk of this fungicide on various organisms, from bacteria and yeast to fish, using a battery of tests (standardized Toxkit microbiotests and acute semi-static tests). By investigating the interaction between Tebuconazole and bacteria and yeast organisms, we observed that Gram-negative bacteria displayed a strong tolerance for Tebuconazole, while Gram-positive bacteria and yeasts proved to be very sensitive. The fish experiment was conducted on Chelon auratus juveniles exposed to five concentrations of the fungicide Tebustar EW (Tebuconazole, 250 g/L as active substance). After 96 h of exposure, the LC₅₀ for C. auratus was 1.13 mg/L. In the case of the Toxkit microbiotests’ application, the following results were recorded: Spirodela polyrhiza EC₅₀ = 2.204 mg/L (after 72 h exposure), Thamnocephalus platyurus EC₅₀ = 0.115 mg/L (after 24 h), and Daphnia magna EC₅₀ = 2.37 mg/L (after 24–48 h). With the exception of bacteria and yeast, the same response pattern was observed for all non-target species tested; the response range expressed by concentrations causing growth inhibition or mortality was small, ranging between very close values that are quite low, thereby demonstrating the high toxicity of Tebuconazole-based fungicides to the environment.

This study provides a comprehensive evaluation of contamination levels in the Romanian Black Sea within the framework of the Marine Strategy Framework Directive (MSFD). Over the course of five oceanographic expeditions between 2020 and 2022, data were gathered from 70 stations in transitional, coastal, shelf, and offshore waters of the Black Sea. Analyses were conducted on water, sediment, and biota samples for key contaminants: heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) such as organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs). The assessment identified contamination hotspots near riverine inputs, urban runoff, harbor activities, and industrial discharges. Offshore waters also showed measurable pollutant levels, likely from diffuse sources and atmospheric deposition. The key findings reveal the widespread contamination of HMs, PAHs, and POPs across the Romanian Black Sea, with concentrations in certain areas exceeding acceptable environmental thresholds, highlighting ongoing challenges for regional pollution management. PAHs were prevalent in both nearshore and offshore regions, while OCPs and PCBs were detected across various matrices, with significant concentrations observed in water and biota samples. The study emphasizes the importance of integrated assessments within the MSFD framework, suggesting that future evaluations should complement the “one out-all out” (OOAO) approach with multi-metric tools, to enhance the robustness of pollution status reporting. Despite improvements in some areas, contamination remains a critical challenge, requiring strengthened regulations, improved waste management, and increased regional cooperation to mitigate the ongoing risks to marine ecosystems. The findings provide valuable data for the upcoming national MSFD assessment cycle (2018–2023) and highlight the need for sustained monitoring and coordinated efforts to ensure long-term marine sustainability.

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.

This study presents an extensive evaluation of the contamination levels in fish, mollusks, water, and sediments in the Black Sea over eight years, from 2016 to 2023. The primary aim was to determine the concentrations and distribution patterns of heavy metals (HMs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and other persistent organic pollutants (POPs) in fish, water, and sediments of the Black Sea, and their implications for marine ecosystem health and human safety. Data were collected through scientific cruises and the methodology involved systematic sampling across different regions of the Romanian Black Sea, followed by rigorous laboratory analyses to identify and quantify the presence of contaminants. The study also examined the temporal trends of these pollutants, providing insights into their sources, pathways, and persistence in the marine environment. Additionally, the research assessed the bioaccumulation of contaminants in various biota, offering a critical perspective on food safety and potential risks to human consumers. The findings revealed significant spatial insights, highlighting areas of concern that require immediate attention and action. Notably, industrial discharge, agricultural runoff, and historical pollution hotspots were identified as major sources of contamination. This research underscores the need for enhanced monitoring and regulatory frameworks to mitigate pollution sources and safeguard the Black Sea ecosystem, advocating for sustainable practices and effective management strategies to preserve marine resources in the Black Sea.

The purpose of this work was to assess the levels of polycyclic aromatic hydrocarbons (PAHs) in some mollusks and fish species, collected during the summer of 2016–2018, from three sites representing the southern, middle, and northern areas of the Romanian Black Sea coast. The PAHs concentrations were determined from the edible tissues of some important seafood (Rapana venosa and Mytilus galloprovincialis mollusk species; Sprattus sprattus, Engraulis encrasicolus, and Trachurus mediterraneus ponticus pelagic fish species and Neogobius cephalarges benthic fish species). The PAHs were analyzed using gas chromatography-mass spectrometry. The average concentrations of these PAHs ranged from below detection limit of 0.0001 to 103.09 ± 11.18 µg/kg wet wt. in mollusk species, from 0.0001 to 147.45 ± 9.28 µg/kg wet wt. in pelagic fish species and from 0.0001 to 45.73 ± 5.28 µg/kg in benthic fish species. Among the two mollusks species, Rapana venosa accumulated significantly higher concentrations (p < 0.05) of PAHs, while among fish species, Trachurus mediterraneus ponticus accumulated significantly higher concentrations (p < 0.05) of total PAHs. Total PAH concentrations varied between the sites; the main presence of PAHs was observed in site 2 (middle location), the major contribution being given by the presence of phenanthrene (Ph), anthracene (An), and naphthalene (Na). PAHs contents in organisms varied according to the different species, their location in the water, their feeding habits (pelagic and benthic organisms) and differences in the quantification of LMW and HMW PAHs. PAH distribution patterns in pelagic and mollusk species are characterized by the abundance of LMW-PAHs. Most of the PAHs had a petrogenic origin, which indicates that the anthropogenic activities influenced PAH concentrations. Apart from Neogobius cephalarges species, the benzo[a]pyrene concentrations, measured in mollusks and fish species did not exceed the EU recommended limit.