Concentration gradient of plastic debris larger than 500 μm detected across the Southwest Indian ocean

items/km²). The majority of plastic debris consisted of hard fragments, primarily polyethylene (45.7%) and polypropylene (26.7%). Our findings provide new insights into microplastic concentrations in offshore regions, highlight the significant degradation of plastic debris, and emphasize the need for further research to identify and map the Indian Ocean's garbage patch along these latitudes. Keys words: Indian Ocean, Marine litter, Visual survey, Manta trawling, Microplastics.