Swash zone sentinels: Unravelling microplastic pollution in selected beaches along the Southwest Coast of Peninsular India using the sand crab, Emerita emeritus

Microplastic pollution has emerged as a significant environmental concern within marine ecosystems globally. Sand crab, Emerita, valued as a food source in various parts of the world, can serve as an indicator of pollution in beach ecosystems. Present study assessed microplastic (MP) pollution across six beaches of Kerala, south west coast of India, by analysing MP in water, sediment, and ingestion by Emerita emeritus. The study evidenced prominent spatial variation in microplastic distribution among the six beaches. High MP concentration was observed in beaches of the south notable for their intense tourism and fishing activities. Microplastic concentration were remarkably high in water compared to the sediment and Emerita. Black MP (38.7 %) were the most prevalent, followed by colorless (37.6 %). Polyethylene (PE) accounted for the majority of MP types (42 %), followed by polypropylene (PP, 39 %) and polystyrene (PS, 19 %). Surface characterization of microplastics extracted from the gut of Emerita using SEM/EDX analysis identified the presence of toxic elements Hg (2.63 wt%) and Al (0.52 wt%) with Ca (11.75 wt%) exhibiting the highest elemental concentration followed by C and O. Presence of adsorbed metals indicates probable bioaccumulation, biomagnification and resultant health hazards to nearshore fishes, birds, and humans upon consumption of Emerita.