Bouzidi_2026_Mar.Pollut.Bull_231_119920

Interactions between engineered nanoparticles and organic contaminants in aquatic ecosystems remain insufficiently known, despite their increasing co-occurrence in coastal environments. This study investigated the effects of gold decorated titanium dioxide nanoparticles (AuTiO NPs), benzo[a]anthracene (Ba), and permethrin (Per) on the Mediterranean mussel Mytilus galloprovincialis, considering both single and binary exposures. Mussels were exposed to 100 microg/L of each contaminant for 14 days, and responses were evaluated using an integrated framework combining physiological performance (i.e. filtration capacity) and biochemical biomarkers in gills, digestive glands, and mantle. Clear contaminant and tissue-specific responses were observed. Filtration capacity was significantly reduced by Ba and Per, with gills showing heightened sensitivity to PAH exposure. Biomarker responses revealed pronounced oxidative and neurophysiological alterations in the gills and digestive glands, whereas the mantle exhibited comparatively lower sensitivity. Mixture treatments highlighted distinct interaction patterns: AuTiO2 + Per induced additive effects on catalase, acetylcholinesterase, and malondialdehyde, while AuTiO + Ba resulted in antagonistic responses, likely reflecting reduced bioavailability through nanoparticle contaminant interactions. These findings demonstrated that mixture toxicity cannot be inferred from single compound effects and depends on both physicochemical interactions and organ-specific responses. Overall, the study underscored the value of multi-tissue and multiple endpoint approaches for evaluating contaminant impacts and highlighted the necessity of incorporating mixture scenarios into ecotoxicological assessment frameworks for coastal ecosystems.