Lgrge scale red tides of Chattonella sp., which is smaller than Chattonella antiqua (HADA) ONO, took plave at the northern part of Kagoshima Bay in 1977 and at Suho Nada, which is located in the western part of the Seto Inland Sea, in 1979.
In order to clarify the mechanisms of the accumulation and movement of Chattonella sp. and of the occurrence and disappearance of these red tides, the relations between the accumulation and factors such as velocity and direction of tide and wind were examined.
The results suggested that the tidal current and wind acted togerher during the accumulation of Chattonella sp. in the Kagoshima Bay, whereas the tidal current mainly acted alone during the accumulation in the Suho Nada. The extraordinary high number (138, 000cells/ml) of the plankton which were found at the innermost part of Kagoshima Bay would be caused by the tidal current and wind acting together with very strong force.