Microplastic Pollution in Sri Lankan Mangrove- Associated Ecosystems: Occurrence, Ecological Implications, and Research Gaps (2015-2025)

Abstract

Mangrove-associated coastal wetlands are increasingly recognised internationally as sites of microplastic accumulation, yet the extent to which this has been documented for Sri Lanka has not been established. This review synthesises literature published between 2015 and 2025 on the occurrence, characteristics, distribution, methodologies, and ecological implications of microplastics in Sri Lankan mangrove-associated ecosystems, distinguishing mangrove-specific studies (sampling within a mangrove stand) from mangrove- associated studies (sampling in nearby lagoons, estuaries, or coastal habitats). Literature was identified through accessible search platforms, institutional repositories, and publicly available peer-reviewed publications; because subscription databases were not directly queried, the review is a structured literature review rather than a full systematic PRISMA review, and its coverage should not be read as exhaustive. Only three mangrove-specific studies were found, concentrated in Negombo Lagoon and five southern sites, while nine mangrove-associated studies document microplastics in nearby lagoons, water, sediment, and biota; four further coastal studies are retained only as national context. Fibers and fragments dominate reported particle shapes, and no Sri Lankan study has sampled biota within a mangrove stand or measured physical or chemical effects beyond ingestion. The most pressing gaps relate to geographical coverage, standardised reporting units, and field-based evidence of ecological effect. Overall, the evidence demonstrates documented contamination and, in lagoon biota, documented ingestion, but not demonstrated ecological damage within Sri Lankan mangroves; closing this gap requires standardised, geographically distributed sampling conducted directly within mangrove stands.