Microplastic occurrence in the diet of green sea turtles (Chelonia mydas) from the coastal region of São Paulo, Brazil

Microplastics (MPs) represent the main vector of pollution in the marine environment. Originating from the slow degradation process of plastics into smaller particles, MPs vary in size between 1 and 5 mm. Their ability to adsorb and transport contaminants, disperse invasive organisms, and be accidentally ingested by marine animals makes these particles an increasing threat to the health of coastal ecosystems and the conservation of marine life. Ingestion of microplastics leads to digestive tract blockage, physiological alterations, changes in feeding behavior, or even total debilitation of the animal. This study analysed and quantified the presence, typology, and colour of microplastics in the gastrointestinal contents of 218 green sea turtle (Chelonia mydas) samples from the Central-South and Northern coasts of São Paulo. Microplastics with an average size between 3 and 4 mm, mostly secondary type and predominantly of white colour were detected in 45.9% of the analyzed samples. Proportionally, microplastics were found in 75% of samples from the Central-South Coast, compared to 35% from the Northern Coast study region. This difference in occurrence is attributed to the higher anthropogenic impact from nearby port and industrial activities. This study enhances our understanding of plastic ingestion by marine fauna. It highlights the urgent need to implement strategies to prevent, reduce, and mitigate plastic pollution and its detrimental effects on the coastal environment.