Unravelling the pathway of macro and micro debris in the beach of uninhabited Semak Daun reef platform, Kepulauan Seribu

Abstract Marine debris is ubiquitous and possess threats to marine organism and ecosystem. Due to its small size, micro debris can be consumed by marine organism. Ingestion of micro debris including microplastic can be detrimental. We investigate the pathway of macro and micro debris in the beach of Semak Daun, an uninhabited island in the Kepulauan Seribu which is famous for tourism. Macro debris sampling was done in the intertidal and subtidal beach, covering both northern and southern part. Micro debris sampling was conducted in the northern part of intertidal beach, three replicate samples were gathered within a radius of 5 m. The most abundance macro debris in the study area were plastic cup and plastic wrap, most of them were found sinking in the seawater. Foam, potentially originated from camping mattress or footwear, composed as the most abundance micro debris. Beach sediment were seen filling the void on the foam surface, a feature that can facilitate density modification which generates foam to sink on the seafloor. Our finding implies that uninhabited island can be polluted by marine debris due to mismanaged waste from tourism. The fact that a large number of marine litters were found in subtidal beach should raise our concern, as hydrodynamic process potentially transported and accumulated them in lagoon or reef front. Further research is crucial to investigate the pathways of marine debris in the reef environment, the result is expected to provide knowledge on better waste management.