Permalink : http://hdl.handle.net/2115/52983

KEYWORDS : Red tide;Chattonella;Bacteria;Population dynamics;Harima-Nada;Seto Inland Sea

The noxious raphidophytes Chattonella spp. and the total numbers of marine bacteria were investigated in Harima-Nada, the Seto Inland Sea, Japan, during the summer of 1989. A red tide of Chattonella occurred in this summer (August). Observed densities of the total number of bacteria (0.50×106～4.16×106 cells mL-1) revealed values observed in common coastal waters in Japan in enbayments of such as the Seto Inland Sea. A peak of Chattonella red tide (about 1,000 cells mL-1) was observed on August 7 and the cells almost disappeared within 1 week, and the total number of bacteria showed the maximum value of 4.16× 106 cells mL-1 at the 10 m depth on August 14. It was suggested that cells of Chattonella red tide were killed by algicidal bacteria after the population peak of Chattonella and resultant organic matters were utilized by heterotrophic bacteria that accompanied the maximum value of bacterial cell density. It is considered that microbial loop worked after the decay of Chattonella red tide via algicidal bacteria, total heterotrophic bacteria and heterotrophic nanofl agellates, etc.