[M-IS20] Ocean Plastics, an earth science perspective

[MIS20-08] TARA-JAMBIO Microplastic Mission : Distributions of microplastics in water surface and sediment of Japanese coastal waters

*Kugako Sugimoto¹, JAMBIO Consortium³, Tara Japan², Sylvain Agostini¹ (1.Shimoda Marine Research Center, University of Tsukuba, 2.Tara Océan Fondation, 3.Japanese Association for Marine Biology)

The Tara Océan Fondation is deidcated to the world’s ocean and collaborates with scientific partners to organise scientific expeditions, raise awareness and educate, mobilize policy makers at the highest level, and enable emerging and developing countries to access the latest knowledge about the ocean. From 2020, the fondation partnered with the JAMBIO, the network of japanese marine stations to start a joint mission on microplastic pollution in japanese coastal waters. Due to their small size, microplastics cannot be fully retrieved from the ocean once they enter it and may cause damage to marine ecosystems and the organisms that ingest them. However there is still an important lack in the knowledge on the quantity, the sources and fluxes of microplastic in the ocean. The mission has two aims: 1) to assess the microplastic pollution in surface waters and sediment of Japanese coasts, the fluxes of microplastics from rivers and bays, and the microbial communities on the plastic fragments, the “plastisphere”; 2) to raise awareness of plastic pollution, promote a reduction in the use of plastic and generally inform on the threats that the ocean is facing due to human activities. A first sampling and outreach mission was conducted at six marine stations in West Japan. Namely sampling were performed at the Ushimado Marine Institute (Okayama University), the Takehara station (Hiroshima University), the Oki Marine station (Shimane University), the Amakusa Marine Station (Kyushyu University) and the Sugashima Marine Biological Laboratory (Nagoya University). Surface water were sampled using a Neuston net and sediment using a Smith McIntyre Sediment Grab. Microplastics were (300 – 5000 µm) extracted using density separation following the degradation of organic materials by peroxide oxidation. For the plastisphere study, microplastic fragments were sampled under the microscope immediately after the sampling. Sampling was conducted in each station at a river mouth, within a bay and outside a bay, in order to assess the horizontal fluxes. Samples are now being analyzed but all surface waters visibly contained microplastic fragments. Outreach activities were also conducted at each location. Moreover a local artist also participated to the sampling and each artists produced a piece of art. Collaboration with artists has been an outreach approach used in all Tara expeditions and allow to reach a new public. The next sampling mission in East Japan is being organized for 2021.