Multidimensional risk assessment of marine litter pollution in the ecologically fragile coral atolls of India.

Abstract

Marine litter (ML), predominantly plastic, threatens oceanic biodiversity and ecosystem functioning globally. However, limited knowledge exists about its impact on India's coastal areas, particularly the Lakshadweep Islands, the nation's sole coral atolls. Within this frame of reference, the present study comprehensively investigated the distribution, abundance, typology, and ecological risks associated with ML across 28 beaches and three lagoon reef stations on Kavaratti Island. A total of 32,710 litter items, divided into 11 categories, were found with an average litter density of 0.82 ± 0.80 items/m². Plastic litter emerged as the most prevalent category across the study area, constituting 63.7% of the total, and public littering was identified as the primary source (43%). Assessments of environmental quality and ecological risk, employing indices like the Clean Coast Index (CCI), Plastic Abundance Index (PAI), Hazardous Litter Index (HLI), Pollution Load Index (PLI), and Environmental Status Index (ESI), identified the Lakshadweep coastline as being at risk due to litter pollution and hazardous litter abundance. The mean concentration of trapped litter on the coral reef was estimated at 1.73 ± 0.46 items/m², with a PLI value of 53.4, indicating an alarming ecological risk and highly perilous condition for the lagoon reef ecosystem. Approximately 5.94% ± 0.18% of coral colonies, particularly of the Porites genus, were found in contact with ML, with a significant proportion displaying signs of disease and tissue loss (59.37%), and partial bleaching or pale (14.86%). The results highlight the growing threat of litter to beach and coral communities, emphasizing the urgent need for effective regional litter management, strengthened policies for banning and phasing out single-use plastics in Lakshadweep, and efficient transportation of non-biodegradable waste to authorized recyclers on the mainland.