PROBLEM TO BE SOLVED: To provide a method for inhibiting increase of harmful algae causing red tides utilizing wave length in specific area. SOLUTION: The method for inhibiting increase in harmful algae causing red tides comprises a method for selectively regulating increase in algae, wherein light having wave length in a specific range effective on selection is irradiated with light intensity effective on selection. Light source comprises LED having 550-670 nm, preferably 590 nm, at its peak. The method enables inhibition of increase in H. circularisquama, K. mikimotoi while maintaining increase in S. costatum. The method is effective on culture of usable microorganisms such as chlorella, prevention of harmful red tides, cultivation of oysters or pearls, and improvement in water system environment. COPYRIGHT: (C)2007,JPO&INPIT
