Uptake of Microplastics in the Wedge Clam Donax trunculus: First Evidence from the Mediterranean Sea

The Mediterranean Sea is affected by microplastic contamination, and several methods have been developed to investigate the degree of environmental plastic pollution. Among these, the use of bioindicators is strongly suggested, and in particular bivalves are sensitive sentinel organisms of the level of microplastic contamination. The wedge clams Donax trunculus is an important edible species for the Mediterranean, area but only rudimentary knowledge is available about microplastic contamination in this species, and no data are available about this topic in the Mediterranean Sea. Therefore, the main aim of this study was to investigate the microplastic accumulation in the wedge clam and in different water samples (seawater and purged water) in the Tyrrhenian Coast from September to June. The microplastics found were characterized by color, shape, and polymer type through micro-FTIR. For the first time, the microplastic contamination in wedge clams of the Mediterranean Sea was recorded. In September was recorded the highest concentration of microplastics in wedge clams (0.56 MPs/individual). Only microfiber shapes of different colors and types of polymers were found in both wedge clams and water samples. Polyethylene terephthalate was the most common polymer in wedge clams, while a diversified composition was found in water samples. The most common size both in wedge clams (42.8%) and water samples (≥50%) was in the range 0.1–1 mm. Our results highlight the presence of microplastics in an edible species widely commercialized in the Mediterranean Basin and the possibility of using this species to assess microplastic pollution.