**Global Environmental Issues Related to Silica Deficiency - Tokyo - 1999-2020s**.

**Global Environmental Issues Related to Silica Deficiency - Tokyo - 1999-2020s**.

The impact of silica (silicon) deficiency in the ocean on ecosystems was discussed at an international workshop held in Tokyo in 1999. Silica is essential for the formation of diatom skeletons, and diatoms are responsible for about 40% of the ocean carbon cycle. However, silica supply in the Yangtze River in China decreased by more than 30% after the construction of the Three Gorges Dam, and diatoms declined significantly in the East China Sea and Yellow Sea. As a result, harmful red tide plankton increased, with noticeable adverse effects on fishery resources and the fishing industry.

To address this problem, EDF of France developed a new discharge technology to maintain silica supply during dam operations. In the 2020s, an international monitoring network will be established in the Asia-Pacific region, and data collection is underway to assess the long-term effects of silica deficiency. These efforts are considered an important step toward sustainable fisheries and marine ecosystem conservation, as well as global environmental management.