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Comparative assessment of size-structured plastic hazards in water, sediment, and edible molluscs from the mangrove ecosystem of southern Kerala, India: Dietary risk and management

Marine Pollution Bulletin 2026
Athira Satheesh, Giya Sara Anil, G. Vineetha, Shahin Shajahan, Shameena Majeed, L. Bindu

Summary

Researchers studying a mangrove forest in India found high levels of tiny plastic particles in the mud, water, and in edible shellfish (like oysters) that people commonly eat from the area. The plastic tends to build up in the sediment first, then gets picked up by shellfish, meaning people who eat these mollusks could be exposed to plastic particles through their diet—though this study didn't directly test health effects, it highlights the need for better pollution control and food safety guidelines in these coastal areas.

Study Type Environmental

Mangrove ecosystems, renowned as coastal protectors, also serve as major sinks of plastic debris. The study assessed size-partitioned plastic pollution in water, sediment, and two edible mollusc species, Telescopium telescopium and Crassostrea madrasensis, from the Ayiramthengu Mangrove Forest (AMF), an ecologically significant environmental hotspot along the southwest coast of India. The distinct habitats, contrasting feeding strategies, and prominence of these edible molluscs in local diets highlight their ecological and dietary significance, making them suitable sentinel species for cross-matrix microplastic (MP) assessment. MP contamination assessed following the NOAA protocols in AMF revealed a high abundance of macro-, meso-, and microplastics in the sediments of Site 1. All analyses were performed using procedural blanks and rigorous contamination controls. The evident spatial variations observed in MP distribution resulted from differences in anthropogenic activities and hydrodynamic transport. Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS) were the major MP contaminants. The pronounced spatial variation in MP distribution, as reflected by the particle abundance, indicated that mangrove sediments act as the primary reservoir, retaining more particles than the surrounding water, thereby enhancing their bioavailability to molluscs and dietary exposure. However, direct implications of MP on human health were not evaluated in this study. The high Polymer Hazard Index and Pollution Load Index of each site indicate the intensity of MP pollution in AMF. Overall, the results of the study provide season-specific patterns and baseline information for future monitoring and management of plastic pollution, prioritizing targeted debris removal and restoration along with implementation of proper dietary guidelines.

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