**History and Current Status of Silica Deficiency in the Global Environment - 1999 to 2020s**

**History and Current Status of Silica Deficiency in the Global Environment - 1999 to 2020s**

In 1999, an international workshop held in Tokyo first extensively discussed the impact of silica deficiency in oceans on ecosystems. Silica is an essential element for the skeletal structure of diatoms, which account for about 40% of carbon circulation in oceans. However, it was noted that dam construction and changes in agricultural runoff have reduced the supply of silica. For example, after dam construction on the Yangtze River in China, silica supply decreased by more than 30%, leading to a decline in diatoms and an increase in harmful red tide plankton in the East China Sea and Yellow Sea.

To address this issue, France's EDF developed new water release technology during dam operations to maintain silica supply, and the University of Tokyo's Ocean Research Institute announced artificial silica supply technology to promote diatom growth. Additionally, researchers from various countries decided to establish a monitoring network to evaluate the long-term impacts of silica deficiency.

By the 2020s, this issue has worsened. Reduced silica supply from the Yangtze River has significantly affected fishery resources, and diatoms in the East China Sea have drastically decreased. As a result, harmful red tide plankton have increased, causing economic damage to fisheries and aquaculture. Meanwhile, Japan, France, and other countries have accelerated technological innovations to realize sustainable marine environments.

Currently, international research and collaboration are underway to mitigate the impacts of silica deficiency. Monitoring networks in the Asia-Pacific region are operational, collecting and analyzing data. These efforts represent a crucial step toward maintaining marine ecosystems and managing global environmental challenges.