Microplastic Concentration in Mediterranean Commercial Fish: A Systematic Review

Nowadays, microplastic (MP) pollution has attracted increasing interest from the scientific community. This systematic review investigated the MP concentration in various tissues of five commercial fish species (Engraulis encrasicolus, Boops boops, Sardina pilchardus, Sardinella aurita, and Trachurus mediterraneus) in different Mediterranean water bodies in order to identify spatial trends and key analytes influencing their variation. The reported concentrations of MPs in all fish ranged from 4.2 particles/individual in the southeastern Mediterranean to 1.2 particles/individual in the western part, but these values are highly uncertain due to inconsistent methodologies, absence of recovery tests, and incomplete data reporting. No significant difference was found in the MP concentration of the different tissues of these species. The key factor affecting the MP concentration was the water body from which they were collected. This systematic review suggests that fewer than six samples may not provide statistically reliable results, and that a lack of detailed data reporting, despite the advances in chemical characterization techniques, continues to limit the robustness of MP studies. Additionally, this study evaluated how methodological differences could influence the reported MP concentrations. These findings offer a comprehensive overview of the MP expansion in the Mediterranean waterbodies and fish species, and provide recommendations for future research design improvement.