Red tide and blue-green algae, which are caused by excessive growth of phytoplankton, have a great impact on fisheries, coastal environment and aquatic life. Various physical and chemical methods, such as clay spraying, deep aeration, and filtration,
have been used as countermeasures against red tide and blue-green algae. However, there is a need to develop better methods in terms of effectiveness, cost, and environmental impact.
It has been reported that algicidal bacteria have the ability to kill microalgae that cause red tides and blue-green algae, suggesting that they may be involved in promoting the disappearance of red
tides and blue-green algae and inhibiting their growth. In addition, algaecides are distributed in high density on the surface of seaweed and water plants, and it is possible that the decrease in water plants promotes the occurrence of red tide and
blue-green algae. Therefore, environmentally harmonized measures are expected to suppress the occurrence of red tide and blue-green algae by artificially creating seaweed beds.
Fig. Blue-green algae in Onuma, southern Hokkaido