Spatial Patterns of Marine Litter on a Remote South Atlantic Ocean Island: Setting Baselines for Monitoring

Abstract Marine plastic litter is a major environmental problem across all oceans, including remote regions. Here, we described the characteristics and spatial distribution of marine litter stranded on the beaches of Trindade Island, in the South Atlantic Ocean, 1200 km off the South American mainland, before the establishment of marine protected areas and the initiation of a long-term research program on the island. Seven beaches differing in exposure to wind and substrate were sampled. A total of 1317 litter items were recorded, with plastics as the main litter (81.9%), mostly hard plastic fragments. Although Lixo Beach had the smallest surveyed area (425 m 2 ), it exhibited the highest litter density (0.74 items/m 2 ) and highest litter-covered area (2.2% of the sampled beach area). Domestic and household purpose items composed the bulk of identifiable items (28.9%), followed by naval (22.5%) and fishery (17.7%) pieces. Litter distribution among beaches differed, with leeward beaches accumulating significantly more and larger litter items than windward beaches, revealing substantial local-scale variation patterns in debris retention. These beaches are characterized by coarse, large pebble substrates rather than sand. Our analysis of pollution indices demonstrated that the Clean Coast Index ( CCI ) and the Plastic Abundance Index ( PAI ) are strongly correlated and suitable for long-term monitoring. This study confirms that oceanic islands are prone to accumulating marine litter, while contrasting results from other studies on Trindade Island emphasize the need for simple yet standardized protocols to support long-term monitoring of plastic pollution in remote environments.