Trophic exposure to environmentally relevant concentrations of nanoplastics induces slight modulation of the antioxidant system in the estuarine bivalve Scrobicularia plana.

Plastic contamination is increasingly recognized as a critical issue in estuarine ecosystems, posing potential threats to aquatic organisms. Although estuaries represent key transition zones for plastics moving from continental sources to the ocean, their ecological fate and effects in these environments remain insufficiently studied. In particular, the trophic transfer of micro- and nanoplastics (NPs) through trophic chains and the associated health risks are still poorly understood. This study aimed to assess the ecotoxicological consequences of trophic exposure to different types of nanoplastics in the estuarine bivalve Scrobicularia plana. The marine microalga Tetraselmis suecica was exposed for 48 h to environmentally relevant NP concentrations (0.008, 10, and 100 µg.L-1). Two categories of NPs were investigated: environmentally derived nanoplastics produced from field-collected macroplastics (ENV NPs) and commercial polystyrene nanoparticles (PS NPs). Following algal exposure, S. plana individuals were fed with NP-contaminated algae, and biological responses were evaluated at both the individual and biochemical levels. RESULTS: revealed that trophic exposure to NPs primarily induced oxidative stress, as evidenced by increased catalase (CAT) activity, with no statistically detectable alterations in condition index, clearance rate, or immune response. Finally, outcomes from this trophic transfer experiment were compared to those obtained in a previous study involving direct NP exposure under laboratory conditions.