GROWTH-POTENTIAL OF GYMNODINIUM-MIKIMOTOI IN GOKASHO BAY

Algal growth potential (AGP) of Gymnodinium mikimotoi was examined at a sampling station situated in Gokasho Bay during a red tide period fr om 1991 to 1994. In the year 1991, 1992 and 1994 when the bloom of G. mikimotoi occurred, the high AGP of seawater at the depth of 1.0 m abo ve bottom (B-1 m) was observed at the order of 10(3) cells/ml before t he peak of the algae. But the AGP did not increase during the period f rom June to August in 1993, the year of no development of G. mikimotoi . These results indicate the possibility of predicting red tide by AGP of seawater at the depth of B-1 m. The growth limiting nutrients in G okasho Bay were also studied using AGP assay. The growth yield of G. m ikimotoi was enhanced by the addition of phosphorus to filtered seawat er prior to development of the algae. When the bloom of G. mikimotoi o ccurred, the lack of phosphorus was not found. Therefore, it was sugge sted that the nutrient factor which control development of G. mikimoto i red tide was phosphorus.