Marine plastic litter in mangrove forests: insights from the endangered ecosystems of the Maldives

Mangrove ecosystems are among the most biologically, ecologically, and economically important coastal environments, offering critical services such as shoreline protection, biodiversity support, carbon sequestration, and fisheries enhancement. Their complex root structures and dense vegetation make them natural traps for marine debris, particularly plastics, with studies showing that plastic accumulation in mangrove forests can be up to four times higher than on sandy beaches. Nevertheless, mangroves remain understudied in the context of macroplastic pollution, with less than 5% of research on marine debris focusing on these habitats. In the Maldives, a Small Island Developing State, plastic pollution is an escalating concern due to a challenging waste management system. In 2020 alone, an estimated 1.6 kilotons of plastic waste entered the marine environment, largely due to landfill leakage, inadequate infrastructure on inhabited islands, and maritime activities. Although mangroves are present on 108 islands, no previous study has documented plastic accumulation in these ecosystems. During three MaRHE Center expeditions in 2024, as part of a national-level survey of Maldivian mangroves, we assessed 28 islands across ten atolls and recorded macroplastic debris in four mangrove forests (14% of sites). The most common items, single-use PET bottles, were found entangled in stands of Ceriops tagal, Bruguiera cylindrica, Rhizophora mucronata, and Pemphis acidula. Accumulations were typically observed in low-lying, wave-exposed embayments with dense vegetation and shallow depressions, suggesting that geomorphology and forest structure are key drivers of debris retention. Plastic waste may obstruct roots, hinder seedling development, and compromise overall forest health. These findings represent the first documented evidence of macroplastic pollution in Maldivian mangroves. Given their recent classification as critically endangered by the IUCN, this underscores the urgent need for targeted conservation measures, improved waste management, and integration of mangrove protection into national marine pollution strategies.