Survival and Copper and Zinc Accumulation in the Pacific Cupped Oyster Magallana gigas Exposed to the Leachable Fraction of Antifouling Paint

Antifouling coatings are an important source of trace metal contamination in coastal marine environments because they continuously release biocidal compounds from submerged structures. Among the metallic contaminants released from many antifouling coatings, copper (Cu) and zinc (Zn) are of particular environmental concern because of their persistence and bioavailability and may accumulate in filter-feeding organisms inhabiting aquaculture areas. The present study evaluated the effects of the leachable fraction of a commercial antifouling paint on survival and Cu and Zn accumulation in the Pacific cupped oyster Magallana gigas. Oysters were exposed for 21 days to three nominal concentrations of an aqueous antifouling paint extract (0, 0.05, and 0.25 mg/L). Copper and zinc concentrations in the exposure media were analytically verified by inductively coupled plasma mass spectrometry, while tissue metal concentrations were determined at the end of the experiment. Survival was analysed using Kaplan-Meier curves and log-rank tests. Mortality showed an increasing trend with exposure concentration, and overall survival differed significantly among treatments, with mortality concentrated in oysters exposed to the highest concentration tested. Both Cu and Zn accumulated in oyster tissues, although their accumulation patterns differed, reflecting distinct physiological regulation mechanisms. These findings demonstrate that the leachable fraction of antifouling paint represents a bioavailable source of Cu and Zn for marine bivalves under controlled exposure conditions. The study provides new experimental evidence supporting environmental risk assessment of antifouling-derived contamination and contributes to the sustainable management of shellfish farming areas.