Abstract Global contamination of aquatic ecosystems by synthetic microparticles has raised increasing concern, yet studies on their ingestion by freshwater invertebrates remain limited. Benthic macroinvertebrates, highly exposed to this kind of contamination, play a key role in aquatic food webs and nutrient cycling. This study investigated the ingestion of synthetic microparticles by benthic macroinvertebrates in the middle Tietê River basin, widely recognized as one of the most polluted rivers in Brazil. Samples were collected from the main river, a marginal lagoon, and a tributary under less human pressure. Contamination was expressive. A total of 129 synthetic microparticles were identified, from 0.02 to 1.78 particles per individual (mean of 0.5), between 7.14 and 900 particles per g of wet tissue. Size the mean values were 1.02 mm (main river), 0.81 mm (lagoon), and 0.64 mm (tributary). The presence of microplastics (polyester and polypropylene) was confirmed; however, cellulose-based fibers accounted for 90.7% of all identified synthetic microparticles. Ingestion rates did not differ significantly among environments, despite noticeable water-quality and hydrodynamics differences, suggesting that factors beyond local pollution levels may influence ingestion patterns. The filter-feeding bivalve Corbicula fluminea showed the highest ingestion values. Results provide the first evidence of synthetic microparticles ingestion by benthic macroinvertebrates in the Tietê River basin and establish an important baseline for future biomonitoring and risk assessment in Neotropical freshwater ecosystems.
Magro et al. (Mon,) studied this question.