Oceanic microplastics in Japan: A brief review on research protocol and present pollution

Microplastics (MPs) are considered a global threat due to their adverse effects on biota. Although there have been many studies of MPs in the environment and experimental studies of their effects on living organisms, insufficient data is available to assess their pollution. Therefore, we have compiled a research protocol for MP and the current status of their pollution in Japan. This review reports MPs in three locations as sea surface water, seafloor sediments, and coastal sediments. Because mesh size of the nets and location of stations relate to the result, this review highlights the importance of survey designs. Shapes, colors, lengths (size), and polymer type of MPs are related to their distribution and abundance and reveal the origination of MPs, so this review recommends reporting baseline data. Eventually, this review organized future issues. • The status of microplastic (MP) pollution in Japan was reviewed. • More local and strategic surveys of MPs are required in Japan. • Baseline data is required for future studies to continue to monitor MP pollution.