Ingestão e efeitos morfofisiológicos dos microplásticos em espécies de peixes da Amazônia Central

Abstract

The Amazon basin is home to the world’s largest diversity of freshwater fish, with approximately 3,000 known species. However, this diversity is severely threatened by pollution, which has altered and impacted the aquatic environment. A recognized anthropogenic impact, and a threat to aquatic biota, is pollution by plastic objects. Due to improper disposal, large quantities of plastics are transported into aquatic ecosystems. In the aquatic environment, plastics undergo weathering and fragment into small particles known as microplastics. In general, freshwater environments have received less attention in relation pollution by microplastics than the marine environment. Microplastics are available for ingestion by a wide range of aquatic organisms, and can cause severe morphological and physiological damage including oxidative stress. Given the harmful effects of microplastics, this study aimed to identify their ingestion by fish species with different dietary habits collected near Manaus, and to evaluate, under laboratory conditions, the effects of microplastic intake on intestinal histology and antioxidant enzymes in Colossoma macropomum (tambaqui). It was found that 61.3% of the individuals analyzed ingested microplastics. Our results also show that the ingestion of microplastics is similar for all dietary habits, regardless of the biometric parameters presented and the location in which these individuals were captured. The morphology and antioxidant enzymes of the intestine were investigated in individuals of Colossoma macropomum under acute exposure (24 h) of microplastics of the polyethylene (PE) type, and only reversible damages in intestinal morphology were evidenced. As for physiology, we found that exposure up to 24 h was not able to induce oxidative stress in the tissue. Further studies should examine organisms from areas considered preserved and subchronic and chronic exposure to microplastics to evaluate the long-term morphophysiological effects.