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One of the most common plastics in the marine environment is polystyrene (PS) that can be broken down to micro sized particles. Marine organisms are vulnerable to the exposure to microplastics. This study assesses the effects of PS microplastics in tissues of the clam Scrobicularia plana. Clams were exposed to 1mgL (20μm) for 14days, followed by 7days of depuration. A qualitative analysis by infrared spectroscopy in diffuse reflectance mode period detected the presence of microplastics in clam tissues upon exposure, which were not eliminated after depuration. The effects of microplastics were assessed by a battery of biomarkers and results revealed that microplastics induce effects on antioxidant capacity, DNA damage, neurotoxicity and oxidative damage. S. plana is a significant target to assess the environmental risk of PS microplastics.

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The clam Ruditapes decussatus is distributed worldwide and due to its ecological and economical interest has been proposed as a bioindicator in areas where mussels are not available. The accumulation of several anthropogenic compounds in their tissues suggests that they possess mechanisms that allow them to cope with the toxic effects of these contaminants. Besides pollutant uptake, the use of biomarkers is pointed out in this paper since it is a promising approach to monitor the effect of these contaminants in the marine environment. Biomarkers complement the information of the direct chemical characterization of different types of contaminants. Therefore, the aim of this paper is to review the role of several biomarkers: (metallothioneins (MT), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx) (total and selenium-dependent), lipid peroxidation (measured as MDA, one of the final products of lipid peroxidation), glutathione S-transferase (GST) and acetylcholinesterase (AChE), measured in different tissues of the clam R. decussatus, in laboratory conditions and under various environmental stresses, in two ecosystems (Ria Formosa lagoon- Portugal) and Bizerta lagoon (Tunisia) in a perspective of a multibiomarker approach to assess environmental changes. Experiment and field studies are in good agreement since MT levels, especially in the gills, the first target tissue of these contaminants, can be used as biomarker of exposure to Cd. GPx and MDA may also be determined in this respect. AChE activity is inhibited by pesticide and, to a less extent, by metal exposure in the gills and whole soft body of clams. However, the induction of GST isoforms experimentally demonstrated is not observed in the field because only global GST activity was determined. The whole set of results opens new research perspectives for the use of this species to assess the effect of mixtures of pollutants in the aquatic environment.

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