Satellite monitoring of ocean surface
chlorophyll a has shown that high concentrations of chlorophyll a had already
begun in late August in the case of the large toxic red tide of 2021. The genus
Karenia, due to its auxiliary pigment, has been reported to be
detectable based on satellite data for K. mikimotoi on the Seto Inland
Sea and the south coast of Ireland, and K. brevis on the west coast of
the Florida Peninsula. Based on the algorithm using these satellite data,
detection of Karenia spp. in the east Hokkaido area should be possible.
Control measures for red tide include the promotion of diatom (competing
organisms) germination by seabed cultivation, algal bed creation
(microbiological control), and the application of active clay (coagulation
removal). What is effective as a control measure for K. selliformis
awaits further research and evaluation. However, it is important to detect
water masses dominated by K. selliformis using an auxiliary dye
algorithm on satellite data and to apply some control measures prepared in
advance before the density becomes as high as a red tide.
