Characterisation of Microplastics in an Isolated Mangrove Island Using Multiple Ecosystem Components Including Brachyuran Crabs
摘要
Mangroves serving as interfaces between land and sea, function as significant filtration and interception systems for environmental microplastics. The structural complexity of mangrove roots enhances their trapping potential, making them prospective sinks for plastics. Microplastics have a strong affinity for mangrove leaves due to their lipophilic surface, temporarily accumulating from both the air and water. Brachyuran crabs, the core processors of mangrove litter can ingest microplastics bound to leaves, potentially transferring them through the food chain to apex predators. Currently, studies from isolated mangrove islands are lacking. So, we conducted a holistic study examining microplastics within multiple ecosystem components of an isolated mangrove island including water, sediment, leaves, stilt root and fallen leaves of mangrove as well as body parts of three species of mangrove crabs. Scanning electron microscopy with energy-dispersive X-ray spectroscopy was carried out to detect the microplastics in roots and leaves. Microplastics were detected in water, sediment, fallen leaves and crabs. Abundance of microplastics in water and sediment was 5.42 ± 0.2 particles/L and 400 ± 86 particles/kg respectively, with the size range > 350 μm. Fallen leaves showed an abundance of 0.06 ± 0.05 particles/cm2. A higher abundance of microplastics was observed in the gastro-intestinal tract of mangrove crabs. Fibre was the dominant morphotype in all components, revealing trophic transfer from water and sediment to crabs via fallen leaves and direct ingestion. The findings indicate that even isolated mangrove islands serve as microplastic repositories, highlighting the pervasive nature of microplastics within the mangrove ecosystem, with implications for the mangrove food chain.