The Henderson Island microcosm: plastic pollution accumulation in the South Pacific

Plastic pollution poses a significant global challenge, with remote islands serving as indicators of broader oceanic plastic trends due to their isolation from direct anthropogenic sources. This study examines plastic accumulation on two islands in the remote Pitcairn Island group: Henderson Island and Oeno Atoll. By analyzing longitudinal data collected over a decade, the research highlights trends in litter accumulation, composition, and potential sources. Henderson Island, previously identified as a pollution sink, showed a marked decrease in annual accumulation rates after a 2019 cleanup, from 284.75 g/m² (2015-2019) to 16.8 g/m² (2019-2024). Despite this reduction, a high litter density (53 items/m²) persists, primarily composed of maritime-origin debris. This study demonstrates that remote islands can be useful for monitoring oceanic plastic dynamics, while emphasizing challenges posed by methodological variation and seasonality. Recommendations include supporting community-led monitoring and management, increasing sample sizes, and enhancing regulation of maritime pollution.