Assessment of multiple ecological impacts of marine litter in the Adriatic Sea: from fishing for litter to fish species

Marine litter (ML) poses several ecological threats to the marine environment and ecosystems. The AdriCleanFish project aimed to study how marine litter can affect fish species and fishing resources. The study was carried out through the removal of marine litter by fishing vessels, the analysis of collected litter, the analysis of floating ML and microplastic ingestion and effects on fish species. The areas of interest were located in the Adriatic Sea (Chioggia and Civitanova Marche fishing fleet areas). The collected material from the sea bottom was characterized to assess weight, volume, number and composition. In addition, the presence of macro-, meso- and microplastics in fish species (European anchovy, hake, European pilchard, sole, horse mackerel and red mullet) was determined. The results show an average concentration of floating microplastics and ML on the surface in line with the average values of the Mediterranean. From ML collected by the ""fishing for litter"" activities from the bottom, the data confirm that plastic materials are the most frequently found (more than 70%) and the most abundant in term of weight. The plastic objects analyzed are mainly disposable and packaging items (eg. bags and bottles), having a land-based origin and they are also related to maritime activities, to fishing and aquaculture. In all the fish species analyzed, the presence of plastic in the gastro-intestinal tracts was detected. On average, 2 fish out of 10 had ingested from one to five microplastics. The pelagic species (anchovy and pilchard) have the highest percentage of occurrence of ingested microplastics. PCBs and PBDEs were also measured in the muscle of fish species as well as biomarker responses in relation to the presence of microplastics in the gastro-intestinal tract (GI) of the target species. The results show negligible effects related to plastic ingestion by fish as well as low levels of contaminant accumulation in fish with microplastics in their GI.