Foraging Habit Determines the Amount of Microplastics Ingested in Five Fish Species from a Northern Adriatic Lagoon

In this study we documented differences in the accumulation of microplastics (MP) in the gastrointestinal tract (GIT) of 5 commercially important lagoon fish species, also considering the concentration of MP in the water column and sediment of a lagoon in the Po River Delta (Northern Adriatic Sea). Two sampling campaigns were carried out in 2021 (spring and autumn), and a total of 201 fish were examined. MP contents in fish species varied widely, with ingestion frequencies ranging from 16% (Atherina. boyeri) to 92% (Chelon ramada). Polyethylene and polypropylene were the polymer types identified in GIT through μ-Raman spectroscopy. There were more fibers than fragments both in the water column and in sediments, but different relative proportions were found in the contents of the GIT of visually-oriented planktivorous and chemically-oriented benthivorous fish. In the detritivorous Chelon ramada a higher concentration of MP (with fibers in greater proportion) was found in comparison to planktivorous and benthivorous fish, probably as a consequence of their passive foraging. Our results indicate that the quantity of MP ingested seems to be more a function of the foraging habits of the species considered, rather than MP availability in the environment