The presence and status of harmful algal blooms (HABs) in Japan are reviewed, revealing a decrease in red tides; however, toxic blooms are found to be increasing in western Japan. Environmentally friendly control strategies against HABs are also compared with integrated agricultural pest management. Very high densities (10⁵–10⁸ CFU/g) of algicidal and growth-inhibiting bacteria were found in biofilm on seagrass and seaweed surfaces and in surrounding coastal seawater. The situation in freshwater ecosystems is similar to coastal seas for toxic cyanobacterium, Microcystis aeruginosa, and aquatic plants. These findings offer new insights into the ecology of influential bacteria and harmful algae, suggesting that protection and restoration of native seagrasses and seaweeds in coastal marine environments should be implemented to suppress HABs. Diatom blooms were successfully induced with bottom sediment perturbation to prevent the occurrence of harmful flagellates such as Chattonella spp. and Alexandrium catenella in the Seto Inland Sea; however, this method requires robust and reproducible verification. “Sato-Umi” is a helpful concept for HAB control in the sea and freshwater ecosystems when adequately managed by people (e.g., appropriate bottom perturbation; protection and restoration of seaweeds, seagrasses, and aquatic plants; application of polycultures of fish, seaweeds, etc.).

审查了日本有害藻华 (HAB) 的存在和状况，揭示了赤潮的减少；然而，日本西部发现有毒水华正在增加。还将针对 HAB 的环保控制策略与综合农业病虫害管理进行比较。 在海草和海藻表面的生物膜以及周围的沿海海水中发现了非常高密度 (10 ⁵ –10 ⁸ CFU/g) 的杀藻和抑制生长的细菌。淡水生态系统的情况类似于沿海海域的有毒蓝藻，铜绿微囊藻, 和水生植物。这些发现为对有影响的细菌和有害藻类的生态学提供了新的见解，表明应该保护和恢复沿海海洋环境中的天然海草和海藻以抑制 HAB。通过底部沉积物扰动成功诱导硅藻大量繁殖，以防止有害鞭毛虫如查通氏菌的发生。和濑户内海的链状亚历山大藻；然而，这种方法需要稳健且可重复的验证。“里海”是一个有用的概念，当人们进行充分管理时（例如，适当的海底扰动；保护和恢复海藻、海草和水生植物；应用鱼类、海藻等混养）。