摘要:Marine debris pollution can threaten the sustainability of natural resources in coastal regions ecosystem. Marine debris is worldwide issue now and Indonesia considered as a second biggest polluter of plastic to the world ocean. Massive efforts have been applied to tackle marine debris, both by the central government and provincial level, to manage these problems and minimize the impact on the coastal ecosystem. Various types of marine debris threaten the mangrove and seagrass ecosystem by covering its roots and leaves, slowing down its growth rate, and even killing them. The aim of this research is to identify the composition of marine debris in estuary waters and mangrove ecosystem. The research activity was conducted in Muaragembong, Bekasi Regency, which is considered part of Jakarta Bay as the source of the marine debris site. The result showed that the marine debris composition during the east monsoon (July) was dominated by plastic with 71%, while during the transition east-to-west monsoon (November) ranged from 59% and equally distributed surrounding estuary waters and mangrove ecosystem. Fifteen types of macro plastic were found in waters in July, larger than those found in November (13 types). The predominant type of macro plastic is Styrofoam, followed by crackle plastic, sachets, and straws, most of which are single-use plastics that are transported to the estuary and then trapped in the mangrove ecosystem.