How do microplastics impact both aquatic life and human health in estuarine regions?

Microplastics are tiny plastic particles less than 5 mm in size that originate from the breakdown of larger plastics or are manufactured as microbeads. Estuarine regions, where rivers meet the sea, act as sinks for microplastics due to their unique hydrodynamics and proximity to human activities. These microplastics can have significant impacts on aquatic life and human health, especially through fisheries.

Pathways of Microplastics into Estuarine Fisheries:
• Runoff from urban areas, carrying plastic waste into rivers and eventually estuaries.
• Direct discharge of untreated or poorly treated sewage containing microbeads from personal care products.
• Degradation of larger plastic debris within the estuarine environment due to sunlight, waves, and microbial activity.
• Industrial effluents and stormwater drainage releasing microplastics into water bodies.
• Fishing activities themselves, such as lost or discarded fishing gear, contributing to microplastic pollution.

Impacts on Aquatic Life:
• Ingestion by aquatic organisms like fish, shellfish, and plankton, which mistake microplastics for food.
• Physical harm such as gut blockage, reduced feeding, and internal injuries in aquatic animals.
• Chemical contamination as microplastics can absorb and concentrate toxic pollutants like pesticides and heavy metals, which then enter the food web.
• Disruption of reproductive and growth processes in aquatic species due to exposure to harmful chemicals associated with microplastics.
• Bioaccumulation and biomagnification of microplastics and associated toxins up the food chain, affecting larger predators.

Impacts on Human Health:
• Humans consuming fish and shellfish from estuarine regions can ingest microplastics and associated toxins.
• Potential health risks include inflammation, disruption of endocrine functions, and exposure to carcinogenic substances.
• Microplastics may act as carriers for pathogens and harmful bacteria, increasing the risk of disease transmission through seafood.
• Long-term impacts on human health are still being studied, but there is growing concern about chronic exposure, especially in communities heavily reliant on estuarine fisheries.