Virgin Polystyrene Microparticles Exposure Leads to Changes in Gills DNA and Physical Condition in the Mediterranean Mussel Mytilus Galloprovincialis

SIMPLE SUMMARY: Microplastic pollution is damaging ecosystems and marine organisms worldwide, and, as this problem is becoming greater, the fate of these marine organisms should be studied. In this study, the physical condition and the DNA integrity of gills of Mediterranean mussels (Mytilus galloprovincialis) have been studied under four microplastic concentrations for 21 days. A worse physical status was shown at the end of the experiment when exposed to highest concentrations; however, DNA damage was higher when exposed to lower concentrations. These results prove that mussels can be affected by direct exposure even at a low microplastic concentration due to their filter-feeding behavior, making them more vulnerable to this type of pollution. ABSTRACT: The ever-growing concentration of microplastics in the marine environment is leading to a plethora of questions regarding marine organisms’ present and future health status. In this article, the Mediterranean mussel (Mytilus galloprovincialis), a commercial species distributed worldwide, has been exposed to 21 daily doses of polystyrene microparticles (10 µm) at four different concentrations that are environmentally realistic (control: no microplastics, C1: 0.02 mg/L, C2: 0.2 mg/L, and C3: 2 mg/L). The physical status through the condition index, and damages in DNA integrity in gills, through DNA fragmentation, were determined. Results showed a minor effect on DNA integrity but a worse physical status at higher doses. Results could be interpreted as a decrease in mussel feeding activity/filtration rates when exposed to high microplastic concentrations, thus reducing the direct exposure to microplastics in gills. These effects could be happening currently and/or may happen in the near future, threatening populations inhabiting microplastics-polluted environments.