High Density of Microplastics in the Caddisfly Larvae Cases

This study aimed to assess the presence of microplastics (MPs) in an urban river (Gari, Lazio, Italy) using case-building caddisfly larvae as potential bioindicators. Results from the benthic faunal assemblage (STAR_ICMi = 0.797) revealed the presence of a rich and well-diversified macroinvertebrate community, thus reflecting a suitable ecological status. Of 279 caddisfly cases collected, 26% contained small plastic particles of various shapes and colours, while 542 MP items per m2 were found in their substrate. Polyvinyl chloride (PVC) and Polyethylene terephthalate (PET) were the most abundant polymers identified by FT-IR analysis found in the Gari River, while the co-presence of lower-density polymers such as polystyrene (PS) and polyethylene (PE) or polypropylene (PP) reflects the contribution of multiple factors controlling MP deposition. The most abundant MPs were of secondary origin, as evidenced by the Carbonyl Index and the predominant shape. Despite the amounts of MPs found in the Gari River, their ecological and chemical status has been classified as “good” during the monitoring campaigns. These results highlight the need to further investigate the environmental impacts of MPs to implement water quality classification indices.