**History and Status of Global Environmental Issues Related to Silica Deficiency - 1999-2020s**.

**History and Status of Global Environmental Issues Related to Silica Deficiency - 1999-2020s**.

In 1999, the impact of silica deficiency in the ocean on ecosystems was first discussed on a large scale at an international workshop held in Tokyo, Japan. Silica is an essential element in the formation of diatom skeletons, and diatoms are responsible for about 40% of the ocean carbon cycle. However, it was noted that silica supply is decreasing due to river dam construction and changes in agricultural drainage. For example, silica supply in the Yangtze River in China has decreased by more than 30% after the construction of dams, and diatom decline and red tide plankton increase have been observed in the East China Sea and Yellow Sea.

To address this problem, EDF of France has developed a new release technology for dam operations, and the Ocean Research Institute of the University of Tokyo in Japan has announced an artificial supply technology to help diatom growth. In addition, a decision was made to establish a monitoring network of researchers from various countries, and a project to assess the effects of silica deficiency over the long term has been initiated.

In the 2020s, the problem became even more acute. Declining silica supply in the Yangtze River has had a major impact on fishery resources, and diatoms have been significantly reduced in the East China Sea. This has led to an increase in harmful red tide plankton, which has manifested itself as an economic blow to the fishing and fisheries industry. Meanwhile, countries including Japan and France are accelerating technological innovations to achieve a sustainable marine environment.

International research and cooperation is currently underway to mitigate the effects of the silica deficit. Monitoring networks are up and running in the Asia-Pacific region, and data collection and analysis are underway. These efforts are important steps toward maintaining marine ecosystems and managing the environment on a global scale.