Can polystyrene nanoplastics be hazardous to polychaetes?

, Silva Marta, Oliveira Miguel, Figueira Etelvina, Martins Manuel, Pires Adília.

Plastics are recognized as persistent pollutants in aquatic environments. Their increased production and environmental release raised concerns about their impact on marine life. Polystyrene (PS) is among one of the most frequently found in the environment since many single use products are made with this polymer. PS, like other polymers, under environmental conditions becomes brittle and breaks down into smaller particles, becoming more available to biota and thus threatening organisms in the water column and sediment, as they gradually sink to the sediments. Polychaetes are the most abundant group in marine ecosystems and create conditions for a more diverse fauna in sediments. As benthic organisms they are exposed to contaminants present in the sediment and as well as in the water. Thus, this study aimed to assess the effects of PS nanoplastics (PS NPs) on biochemical endpoints associated with oxidative status and damage, behavior and regenerative capacity of Hediste diversicolor. H. diversicolor specimens were collected at a reference site in the Aveiro lagoon (Portugal), and after depuration and acclimatization, they were exposed, for 28 days, to five different concentrations of 100 nm PS NPs (0.0; 0.005; 0.05; 0.5; 5.0; 50.0 mg/L). Results demonstrated the capacity of PS NPs to impact the activities of important antioxidant enzymes such as glutathione peroxidase (0.005 and 0.05 mg/L) and catalase (0.05 to 50 mg/L), and enzymes of phase II of biotransformation glutathione S-transferases (0.05 to 50 mg/L). The ability of these particles to induce oxidative damage was also observed. Protein oxidation occurred in organisms exposed at 0.05 to 50 mg/L. Effects were also reported at the individual level. Organisms took longer to bury (0.005 to 0.5 mg/L) and presented a decreased body regeneration (0.005 and 5 mg/L). Overall, the results highlight that PS NPs may have an impact on the population of polychaetes.

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