Microplastic distribution and risk assessment in estuarine systems influenced by traditional villages and artisanal fishery activities

Microplastics (MPs) are widespread in oceans worldwide, posing a significant threat to aquatic ecosystems. The abundance of these particles in water is related to population density and urban development, functioning as a sink for MPs. However, the pollution levels due to the accumulation of MPs in the estuarine in Amazonian mangrove areas remain unknown. Here, we show that population density and fishing activities influence the distribution of MP pollution in these waters. We found the highest abundance of MPs in the inner (1.03 items/m³) and outer (0.82 items/m³) portions of the estuary, corresponding to the areas with the highest population density and fishing activity, respectively. The main morphological characteristics of MPs are fibers (89.8%), blue color (55.2%), and size of 1000-2000 μm (31.7%). The risk analysis showed a low level of danger, suggesting that the potential impact on the ecosystem is still small. Our results demonstrate that the presence of human populations and their fishing activities significantly influence the accumulation of MPs in the estuarine waters on the Amazon coast. Based on our findings, more sophisticated analysis using MPs' spatial distribution models can be associated with hydrodynamic processes, aiming to define pollution hotspots and support the mitigation of their emerging negative effects. In addition, monitoring and generating valuable information are the main targets for developing comprehensive strategies to preserve biodiversity and sustainability in the Amazon coastal zone.