Meta-analysis of the spatial distribution and composition of plastic macro-debris in Indonesia

Plastic pollution is recognised as a global environmental problem with Indonesia identified as a major contributing source. However, a comprehensive understanding of pollution patterns remains hindered by fragmented data and methodological inconsistencies across studies. This study synthesises data from 44 peer-reviewed publications, spanning 68 field locations and 328 individual study sites across 19 provinces, to map the spatial distribution and composition of plastic macro-debris in Indonesia. We identified plastic bags, plastic food packaging, and plastic bottles as the three most prevalent item types, occurring as top three ranked items in 65 %, 63 %, and 40 % of field locations, respectively. Items were recorded across seven different environment types: beach (n = 43 field locations); river (n = 16); mangroves (n = 3); seabed (n = 2); coral reef (n = 2); sea surface (n = 1) and inland areas (n = 1), with research effort concentrated in Java, accounting for 40 % of all field locations. Despite Indonesia's environmental and regional diversity, multivariate analysis revealed no significant differences in litter composition between environment types or provinces, indicating that common plastic items dominate pollution across Indonesia. These findings underscore the need for coordinated national action targeting high-prevalence items and highlight the value of widespread beach litter monitoring as a proxy for broader environmental pollution patterns.