Regional differences in microplastic accumulation in the thornback ray (Raja clavata) along the southern Black Sea coast

Abstract

Microplastic (MP) pollution is an emerging global concern with potential ecological and human health consequences, yet data on its impacts in demersal cartilaginous fishes remain scarce. This study presents the first assessment of MP ingestion in the thornback ray ( Raja clavata ) specifically focusing on the southern Black Sea coast. A total of 68 individuals collected from 23 stations were examined, yielding 196 MP particles. The mean abundance was 2.88 MPs per individual, with significantly higher values in the eastern Black Sea compared to the western region (Mann–Whitney U, p = 0.036). Fibers dominated the morphological categories (>80 %), while PET and PP were the most prevalent polymer types, and black and blue were the dominant colors. The eastern coast exhibited greater polymer and color diversity, which suggests a potential association with heterogeneous land-based inputs. No significant correlations were found between MP abundance and fish length, weight, or sampling depth. These findings highlight spatial heterogeneity in MP contamination, emphasizing areas of accumulation consistent with regional riverine discharges and coastal pressures. The results highlight the potential importance of targeting land-based sources to support conservation efforts in sensitive marine ecosystems.