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Marine debris (MD) is a global issue that remains unresolved in Indonesia where the accumulation of this kind of pollution poses a significant threat to the marine ecosystem and health of the ocean. Understanding the sources and locations of stranded debris is crucial in identifying the required regulations and mitigation strategies. This study used the hypothetical sources to identify the stranded debris along the coastline of Selayar Island and its surrounding seas. Using a combination of simulation and in-situ sampling methods, the simulation considered 13 hypothetical sources based on external factors such as river locations and surface ocean currents. This simulation result was then validated the simulation against beach litter observations and interview results with people. The results successfully mapped the sources and stranded MD in Selayar Island, indicating that the majority of MD originates from the island itself and the surrounding areas, influenced by oceanographic factors. The most frequently encountered locations of stranded MD are in the western coastal region including tourism areas and coastal ecosystem. Due to the oceanographic conditions, the stranded debris has varied quantities over the months, and higher in December represent the northwest monsoon (NWM) season, exceeding levels observed during the southeast monsoon (SEM). The study also identified that the main sources of debris are from Selayar Island and rivers from surrounding islands. This study also confirmed that oceanographic conditions such as surface ocean currents and wind pattern influenced the spreading of MD in Selayar Island. Due to the different ocean characteristics in different regions, a more detailed understanding and stranded of marine debris source which might provide more information for the explanation of the mechanism of marine debris pathways in Archipelagic Countries., (© 2024. The Author(s).)

Even though Pacific - Indian Ocean exchange [Indonesian Throughflow (ITF)] has been measured for the last three decades, the measurements of microplastic in the region is very limited. This study was the initial investigation of the vertical distribution of microplastic in the deep-sea areas across the ITF Pathway. Niskin water samples were utilized to obtain the samples from a water column in a range of 5 to 2450 m. A total of 924 microplastic particles with an average abundance of 1.062 ± 0.646. n/L were found in the water column. Our findings indicate that water temperature and water density are the most significant factors correlated to the microplastic concentration. This study will be the first report discussing the distribution of microplastics in the deep-sea water column that could be highly significant in determining the fate and transport of microplastic within Indonesian waters that exits into the Indian Ocean., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Anisakis spp. (Nematoda: Anisakidae) parasitize a wide range of marine animals, mammals serving as the definitive host and different fish species as intermediate or paratenic hosts. In this study, 18 fish species were investigated for Anisakis infection. Katsuwonus pelamis, Euthynnus affinis, Caranx sp., and Auxis thazard were infected with high prevalence of Anisakis type I, while Cephalopholis cyanostigma and Rastrelliger kanagurta revealed low prevalence. The mean intensity of Anisakis larvae in K. pelamis and A. thazard was 49.7 and 5.6, respectively. A total of 73 Anisakis type I larvae collected from K. pelamis and A. thazard were all identified as Anisakis typica by PCR-RFLP analysis. Five specimens of Anisakis from K. pelamis and 15 specimens from A. thazard were sequenced using ITS1-5.8S-ITS2 region and 6 specimens from A. thazard and 4 specimens from K. pelamis were sequenced in mtDNA cox2 region. Alignments of the samples in the ITS region showed 2 patterns of nucleotides. The first pattern (genotype) of Anisakis from A. thazard had 100% similarity with adult A. typica from dolphins from USA, whereas the second genotype from A. thazard and K. pelamis had 4 base pairs different in ITS1 region with adult A. typica from USA. In the mtDNA cox2 regions, Anisakis type I specimens from A. thazard and K. pelamis showed similarity range from 94% to 99% with A. typica AB517571/DQ116427. The difference of 4 bp nucleotides in ITS1 regions and divergence into 2 subgroups in mtDNA cox2 indicating the existence of A. typica sibling species in the Makassar Strait.