Anthropogenic litter pollution in the mangrove blue carbon ecosystem: Unveiling the spatial distribution, composition, source delineation and mitigation measures along the Goa coast, India

• Coastal mangroves in Goa face alarming levels of anthropogenic litter pollution. • Plastic items were ubiquitous, accounting for 66 % of anthropogenic litter. • Plastic litter includes single-use plastic items and discarded fishing gear. • Land-based mismanaged solid waste and public littering were identified as primary sources of litter pollution. • Mitigation strategies emphasize science-informed policy formulation, community engagement, and education. Plastic litter pollution has emerged as a critical environmental issue globally, and coastal habitats are particularly vulnerable to its detrimental effects. The west coast of India, renowned for its rich biodiversity and vibrant ecosystems, is facing escalating challenges due to the increasing prevalence of mismanaged plastic litter in its coastal areas. However, the scale of plastic accumulation in the coastal environment in this region remains largely unknown due to limited research. This study aims to comprehensively assess the extent, sources, and impacts of plastic litter in coastal mangroves, an important blue carbon habitat, along the Goa coast, while also proposing effective mitigation strategies. Our findings reveal alarming levels of plastic litter in the study areas. The mean concentration of trapped litter was estimated at 5.14 ± 0.55 items/m² (ranged 3.3 - 12 items/m²). Overall, plastic was the most significant litter type, contributing to 66% of the total litter accumulation. Source identification analysis suggests that 89% of the litter in the mangrove originated from local land-based sources. Common plastic items identified include plastic fragments, single-use plastic items and fishing gear. Four indices—Clean Coast Index (CCI), General Index (GI), Hazardous Items Index (HLI), and Clean Environment Index (CEI)—were used to evaluate environmental and health risks. Mangrove pneumatophores and branches were observed to be impaired by entangled plastic. Additionally, trapped plastic may pose a serious risk to mangrove biodiversity, disrupt the ecological balance, and impact human health through the food chain. The study recommends sustainable mitigation strategies, including policy reforms, community engagement, and educational initiatives, to address plastic pollution in important blue-carbon ecosystems like mangroves. By adopting a multidisciplinary approach, present study contributes valuable insights and actionable recommendations to safeguard the coastal ecosystems, preserve biodiversity, and ensure sustainable development in the region.