Ecotoxicological impact of residual polycyclic aromatic hydrocarbon pollution in the largest Brazilian marine protected area: A multibiomarker approach in the marine clam Tivela mactroides.

An unprecedented oil spill occurred along the Northeast Coast of Brazil in late 2019, affecting the Environmental Protection Area Costa dos Corais (APACC), the largest Brazilian marine conservation unit, posing a risk to this complex ecosystem. By applying passive ecotoxicological biomonitoring, this study aimed to evaluate whether the remaining contamination from such an oil spill affected the population of the marine clam Tivela mactroides by assessing multiple biomarkers, regarding antioxidant enzyme activities (SOD, CAT), biotransformation (GST, GSH), oxidative damage (MDA), and neurotoxicity (AChE) in gills and digestive glands, and PAH bioaccumulation. The clam tissues and sediment were sampled in three locations (Paripueira, Japaratinga and Maragogi beaches), which were differently affected by the accident, and during three sampling periods, starting one year after the accident began. We detected Σ16PAHs in the clam soft tissues and in the sediment samples, all with relatively low concentrations. Differential biomarker responses were observed in both clam tissues, as denoted by the Integrated Biomarker Response Index (IBR). However, there was no correlation between PAH bioaccumulation and biomarker responses in T. mactroides, suggesting the occurrence of multiple stress factors in such a marine protected area. This study demonstrated that multiple biomarkers assessment in the marine clam T. mactroides is a suitable approach for biomonitoring of marine areas in Brazil affected by the 2019 oil spill. However, we emphasize that further long-term studies must be conducted to better understand the environmental impacts caused by an oil spill of such magnitude.