A domestic research team investigated deep-sea organisms and, for the first time in the world, identified that more microplastics settle in the Indian Ocean than in the Pacific. Microplastics are fragments of 5㎜ or less that result when large plastic waste entering the ocean breaks apart due to sunlight and waves. The team analyzed that heavy inflows of plastic trash from South Asia and East Africa, which are undergoing rapid industrialization, are polluting the Indian Ocean.

A team led by Drs. Kim Se-ju and Jeong Jin-yeong at the Korea Research Institute of Bioscience and Biotechnology, together with a team from the Korea Institute of Ocean Science and Technology, analyzed the characteristics of microplastics inside marine organisms collected near ‘hydrothermal vents’ in the North Fiji Basin of the Pacific and along the Central Indian Ridge, and released the results on the 9th. The findings were published in the international journal ‘Water Research’. This is the first study in the world to compare patterns of deep-sea microplastic contamination between different oceans.

A hydrothermal vent is a place where deep-sea seawater that has seeped into cracks in the crust is heated by hot magma and gushes out. The venting seawater contains large amounts of chemical substances necessary for ecosystem formation. For this reason, a variety of organisms live around hydrothermal vents even without sunlight.

The team collected and analyzed a total of 12 specimens of deep-sea snails and mussels that live near hydrothermal vents at depths greater than 2000ｍ on the seafloor of the Pacific and Indian Oceans. Microplastics were found in 92% of the collected organisms.

Notably, microplastic contamination was more severe in the Indian Ocean than in the Pacific. According to the team, organisms collected in the Indian Ocean had up to 14.7 times higher concentrations of microplastics per body weight than those from the Pacific.

The team analyzed, “The inflow of plastic waste from South Asia and East Africa (near the Indian Ocean), where rapid industrialization is underway, appears to be the cause.” In fact, large amounts of the plastic ‘acrylonitrile’, which is widely emitted from fiber and resin industrial zones in South Asia, including India, were detected in organisms collected from the deep sea of the Indian Ocean.

The team also found that the locations where microplastics are detected differ according to internal anatomy. In snails, they were found mainly in the digestive system, whereas in mussels they were detected throughout the body. Snails have anatomical features that prevent substances entering the intestine from spreading to other parts such as muscle. Mussels do not. They feed by ‘filter feeding’, circulating seawater along with food throughout the body.

Dr. Kim Se-ju stated, “This study shows that pollution from plastics has spread even to areas near hydrothermal vents,” adding, “It is expected to serve as basic data for establishing future deep-sea environmental monitoring and public health policies.”