Using otolith and body shape to discriminate between stocks of European anchovy (Engraulidae: Engraulis encrasicolus) from the Aegean, Marmara and Black Seas.

European anchovy, a small pelagic fish, plays a significant role in the blue economy, with remarkable commercial, ecological and culinary values. In this study, the variability in the shapes of the body and sagitta otoliths was examined to identify the different anchovy stocks in the Black Sea (26.5°E-39.9°E, 38.7° N-42.1°N) and adjacent regions, i.e., the Sea of Marmara and the Aegean Sea. The body shape was assessed with geometric morphometrics, while shape indices and elliptic Fourier analysis were used to evaluate the shape of the sagitta otoliths. The data were analysed using multivariate and univariate analysis of variance, discriminant function and principal component analysis. The anchovy population could be divided into five distinct stocks based on body shape, with an overall leave-one-out cross-validated correct classification of 85.6%. The geometric morphometrics revealed significant differences in body depth, snout, lower jaw and caudal fin. The differences in sagitta otolith shape also revealed the existence of four distinct stocks with an overall leave-one-out cross-validated correct classification of 46.5%-69.3%. The elliptic Fourier analysis revealed two main stocks of anchovy from the Black Sea as the Eastern-Middle Black Sea stock and the Western Black Sea stock. Based on the elliptic Fourier analysis, the differences in the sagitta otoliths increase in magnitude with increasing geographic separation, first manifested at the otolith anterior notch, followed by changes in the otolith width. The findings affirmed the existence of distinct stocks that should have important implications for effective management of this pelagic fish in the Black Sea and adjacent regions.

Trace elements in edible tissues of the veined rapa whelk (Rapana venosa) in the southern Black Sea, Türkiye: sex, monthly, and age variations and human consumer health risk.

Coastal areas face significant pressures from a variety of human activities, owing primarily to population growth in these areas. Human activities produce a variety of contaminants, including trace metals, which are common forms of contamination that enter marine ecosystems. This study was carried out to provide information on trace element concentrations (Hg, Pb, Cd, Cu, and Zn) in the muscles of Rapana venosa (Valenciennes, 1846) available on Sinop coasts of the southern Black Sea and to evaluate the possible risk associated with their consumption. The minimum and maximum values (mg/kg wet weight) of trace elements in the edible tissue of R. venosa decreased in the following order: Zn (1.75-8.53) > Cu (0.41-4.6) > Cd (0.021-0.255) > Pb (0.013-0.037) > Hg (0.010-0.035). The measured levels of all the trace elements in the present study were lower than the limits permitted by the European Community Regulation (EU), Turkish guideline, and the UK Ministry of Agriculture, Fisheries and Food (MAFF). The hazard index value of Hg, Cd, Cu, and Zn for the veined rapa whelk is lower than standard 1, demonstrating that ingestion of this mollusk from the southern Black Sea does not result in overexposure to these contaminants. The risk index value for human cancer risk of Pb for all seasons was found to be insignificant. When comparing the levels of elements in males and females, significant differences were found in some months for all the metals. In general, the trace elements were detected in higher concentrations in females than in males. Both females and males have accumulated less trace elements with increasing age. This study was the first to show the distribution of trace elements as a function of age in R. venosa.

Seasonal and spatial variations of marine litter on the south-eastern Black Sea coast.

The south-eastern Black Sea coast in Turkey was evaluated for marine litter composition and density covering nine beaches during four seasons. The marine litter (>2cm in size), was collected from the coast and categorized into material and usage categories. The data analysis showed that plastic was the most abundant litter (≥61.65%) by count and weight followed by styrofoam and fabric. The marine litter density ranged from 0.03 to 0.58 with a mean (±SD) of 0.16±0.02 items/m2 by count. Based on weight, it varied between 0.44 and 14.74g/m2 with 3.35±1.63. The east side had a higher marine litter density than the west side with significant differences between beaches. The variations due to different seasons were not significant for any beach. The results of this study should provide baseline information about the coastal marine pollution and will assist the mitigation strategies.