Metal and metalloid bioaccumulation and oxidative stress in the invasive bivalve Mytilopsis leucophaeata (Bivalvia, Dreissenidae) from a highly anthropogenically-impacted coastal lagoon in Southeastern Brazil.

Bivalves are adequate aquatic pollutant bioindicators due to their sessile and filter-feeding habits. However, not many studies have been carried out on elemental concentrations in the invasive Mytilopsis leucophaeata, despite its wide geographical distribution, and no assessments on biochemical metal and metalloid effects are available for this species. This study investigated elemental contamination associated to oxidative stress in M. leucophaeata for the first time in an anthropically impacted lagoon in Rio de Janeiro, Brazil. A total of 240 mussels were sampled between 2022 and 2023, 60 per sampling season. Metals and metalloids were quantified in soft tissues and lagoon surface water by ICP-MS and reduced glutathione (GSH), lipid peroxidation (LPO) and protein carbonylation (PTC) were measured. New COI and ITS1-5.8S-ITS2 sequences for this species are provided. Most elements were higher in spring and summer. Significant strong correlations were observed between several essential and toxic elements, such as Co vs. As, Cu vs. As, Cu vs. Cd and Zn vs. As, with all detected correlations presenting r values over 0.84. The highest PTC and GSH were observed in summer (472.5 μmol g) and autumn (0.65 μmol g), while LPO was higher in spring and summer (935.0 and 760.4 μmol g, respectively) alongside higher elemental concentrations. These findings indicate that elemental contamination is significantly associated to oxidative stress profiles and that in M. leucophaeata is an adequate biomonitoring tool concerning metal and metalloid effects. Finally, M. leucophaeata were deemed unsafe for consumption due to high As, Cr, Se, and Zn levels, exceeding national and international safety limits.