Microplastics (MPs) are emerging contaminants in marine environments and pose a serious threat to the marine ecology. MPs arise from land sources, deterioration of larger plastics, or intentionally manufactured as “primary” microparticles. MPs can be found in diverse shapes and sizes, and the long-term effect on marine ecosystems is yet unknown. In most cases, sediments are the final sink for MPs. Marine organisms are vulnerable to MPs exposure, however, the ecotoxicological effects on aquatic organisms is still poorly understood. This study assesses the antioxidant response of the estuarine bivalve Scrobicularia plana when exposed to virgin PE microparticles. Two size classes of S. plana were exposed for 96 hours to a range of environmentally relevant PE concentrations. A battery of biomarkers was selected to determine the ecotoxicological effects of PE MPs and to assess the potential use of enzymatic biomarkers for bioassays, including the activity of antioxidant enzymes and oxidative damage. This work reports that GST activity increases significantly under the highest concentration (450 MPs L-1), possibly being the best enzymatic biomarker to assess the presence of PE microparticles. The present work provides evidence of the effects of PE microparticles and the efficiency of enzymatic biomarkers for ecotoxicological assays.
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