Accumulation Evaluation of Potential Microplastic Particles in Mytilus galloprovincialis from the Goro Sacca (Adriatic Sea, Italy)

Microplastics (MPs; <5 mm) are present throughout the marine environment and are recognized as an emerging threat to aquatic ecosystems. Filter feeding organisms, such as mussels, are considered as bioindicators of MP pollution and are useful to evaluate the potential risks of MPs to human health. The work presented shows data on potential MPs found in Mytilus galloprovincialis samples collected from the Adriatic Sea during two sampling sections (1st sampling: December 2019 and 2nd sampling: May 2020). The mussels were subjected to digestion with H2O2 individually and filtered and the MP elements found were observed using a stereomicroscope and ultimately categorized by shape, size class and color, with the aid of a digital camera and data acquisition software. The highest MP concentrations were observed in the mussels collected in December 2019 (1.11 microplastic items per gram wet weight of mussels' tissue), highlighting the possible influence of the following two main factors: greater river discharges following adverse weather events and higher river water pollution due to industrial activities. Indeed, the second sampling was performed after the Italian lockdown, due to the COVID-19 emergency. MP fibers (50-80%) were the most abundant type of MPs identified, followed by fragments (10-40%), granules (1.5-2.5%), non-categorized shape (1-2%) and foam (<1%). The color black (50-70%) and sizes smaller than 500 mu m were the most dominant characteristics recorded both in the 1st sampling (50-70%) and the 2nd survey (30-50%). These data could be overestimated, due to the lack of polymer identification. The results of this study provide further data on the importance of bivalves as environmental bioindicators with regard to the pollution of MPs in the Adriatic Sea, supporting their instrumental role as environmental bioindicators for MP pollution.