Microplastic retention in European flat oyster Ostrea edulis cultured in two Mediterranean basins

Oysters, as filter feeders, intercept and retain microplastics (MPs), making them bioindicators of environmental contamination and a potential risk to human health. MP accumulation was assessed in two life stages of cultured Ostrea edulis from the Adriatic and Tyrrhenian Sea in the Mediterranean basin. The productive areas share similar environmental conditions highly differing in industrialization level. The results show that human activities directly influence the quantity and quality of MPs found. Oysters from the Tyrrhenian basin showed higher contamination and higher occurrence of spheres, reflecting the inland industrialization level. The MP size class between 50 and 150 μm was the most abundant in both basins, overlapping the diet plankton size and suggesting that species trophic ecology is a key driver in MP interception. This is the first MP-exposure assessment on O. edulis in the Mediterranean basin, laying the groundwork for future studies on risk assessment within the “One Health” approach.