Unraveling the invisible threat of microplastics to Lakshadweep Coral Atolls, Indian Ocean: Multifaceted ecological risk and pollution profiling

Microplastics (MPs) are widespread in oceans, posing growing threats to coral reefs critical for tropical and subtropical biodiversity. However, in situ studies on MPs pollution in coral reefs remain limited. This study investigates the prevalence, characteristics, and ecological risks of MPs across the Lakshadweep archipelago, India's only coral atolls. MPs concentrations in surface seawater ranged from 10.75 ± 6.18 to 211.5 ± 207.31 items m⁻³ , while sediments ranged from 54 ± 21.48 to124.25 ± 76.63 items kg⁻¹ . Most MPs were fragments and fibers, smaller than 1 mm, primarily white and blue, with polyethylene, polypropylene, and polyethylene terephthalate as dominant polymers. Risk profiling using the Pollution Load Index, Polymeric Risk Index, Potential Ecological Risk Index, and Environmental Status Index identified high MPs pollution risks. The Integrated Microplastic Risk Index (IMRI) provides a holistic evaluation by objectively weighting multidimensional pollution attributes of MPs, classifying most islands as high risk and indicating that Lakshadweep's coral ecosystems are highly exposed to MPs pollution, suggesting that IMRI may be more suitable for coral reef ecosystems. Furthermore, Monsoon-driven currents, wind, and seasonal dynamics influence MPs transport and accumulation, with the Laccadive High during the winter monsoon creating convergent circulation near Lakshadweep, leading to localized MPs accumulation. These findings highlight the urgent need for continued monitoring and mitigation of MPs pollution in the Lakshadweep Sea.