Effects of floods resulting from climate change on metal concentrations in whiting (Merlangius merlangus euxinus) and red mullet (Mullus barbatus) and health risk assessment.

In this research, the effect of flooding caused by heavy precipitation, postulated to be one of the consequences of climate change, on toxic metal concentrations in two demersal fish species, whiting (Merlangius merlangus euxinus) and red mullet (Mullus barbatus), was investigated. For both demersal fish species, concentrations of Hg, Fe, Cd, Pb, Se, Al, Zn, Cu, Sr, B, Cr, Mn, Ni, Ba, and Li were compared between samples taken from Türkeli, Sinop, Black Sea, before and after the flood event in August 2021. Hg, Mn, Se, Li, B, and Sr metal concentrations increased in whiting and in red mullet in the post-flood samples. Estimated daily intake, target hazard quotient, cancer risk, the maximum allowable daily consumption rate and minimum daily requirements, and health risk analyses indicated that daily consumption of whiting and red mullet was risky due to the heavy metal Hg level after the flood. In addition, it was found that the samples had higher levels of Se than Hg, Se/Hg ratios were above 1, and Se-HBV were positive. Therefore, whiting and red mullet fishing should be restricted for a limited time period in the region.

Microplastic-induced oxidative stress response in turbot and potential intake by humans.

Microplastic (MP) pollution has become a health concern subject in recent years. Althoughann increasing number of studies about the ingestion of microplastics by fish, research on the oxidative stress response to MPs in natural environments is quite limited. In this study, the identification and characterization of MPs in gill (G), muscle tissues (M), and gastrointestinal tract (GI) of turbot (Scophthalmus maximus) were evaluated. Oxidative damage of MPs on the brain (B), liver (L), gill (G), and muscle (M) tissues as well as their effect on superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), paraoxonase (PON), arylesterase (AR) myeloperoxidase (MPO), and malondialdehyde (MDA) biomarkers were evaluated. The potential transmission of MPs from muscle tissues to humans was examined. Results showed that gills contain the highest amounts of MPs, ethylene propylene is the most dominant polymer type, black and blue are the most common MP color, fiber is the most common shape, and 50-200 µm is the most common MP size. Results showed that MPs cause oxidative stress of tissues with inhibiting effect on enzyme activities and promoting impact on lipid peroxidation. The oxidative damage mostly affected the liver (detoxification organ) followed by gill tissue. The intake of MPS in the European Union was estimated by EFSA as 119 items/year, while in Turkey it is 47.88 items/year. This study shows that more research is needed in terms of ecosystem health and food chain safety. The risk assessment of MPs in living organisms and environmental matrices including food safety and human health should be considered a public health issue.

Microplastics in Tissues (Brain, Gill, Muscle and Gastrointestinal) of Mullus barbatus and Alosa immaculata.

The researches on MPs in commercial marine fish are very limited although in marine environments microplastic (MPs) pollution is a global problem. In this study, the presence, composition, and characterization of MPs in different tissues (brain, gill, muscle, and gastrointestinal tract) of commercial fish species [red mullet (Mullus barbatus) and pontic shad (Alosa immaculata Bennett 1835)] from the Black Sea were investigated. M. barbatus (demersal) and A. immaculata (pelagic) fish were preferred in the selection of fish species in order to represent demersal and pelagic environments. After dissected the fish, MPs were obtained from the tissues by extraction using the flotation method; then the MPs were counted and categorized according to shape, size, and color. The composition of the MPs was determined via ATR-FTIR spectroscopy. In terms of microplastic abundance in fish tissues, the gastrointestinal tract (40.0%) ranked first in both fish species, while the lowest MPs density was determined in brain tissues (7.0%). After the gastrointestinal tissue, gills were identified as the second tissue with the highest MPs density. Regardless of fish species, MPs characterization was mainly fibrous (51.0%), black colored (49.0%), and 50-200 µm in size (55.0%). Among the nine different polymers determined, polychloroprene (18.8%) and polyamide (15.0%) were found most frequently. This research provides data for tissue-based assessment of MPs in fish. The obtained data showed that MPs (one of the anthropogenic pollutants) are quite high in all tissues regardless of fish species. Moreover, it has emerged that these two fish species are suitable for monitoring microplastics in the study area.