CS16 Harmful Algal Blooms
Date: Wednesday, June 12, 2002
Time: 2:45:00 PM
Location: Sidney
 
TomaruY, Japan Science and Technology Corporation, Hiroshima, Japan, tomaruy@affrc.go.jp
Nagasaki, K, , Fisheries and Environment of Inland Sea, Fisheries Research Agency, Hiroshima, Japan, nagasaki@affrc.go.jp
Tarutani, K, , FEIS, FRA, Hiroshima, Japan, tarutani@affrc.go.jp
Yamaguchi, M, , FEIS, FRA, Hiroshima, JAPAN, mineo@affrc.go.jp
 
COMPLEX RELATIONSHIP BETWEEN A LYTIC VIRUS (HAV) AND ALGAL HOST (HETEROSIGMA AKASHIWO) IN NATURE
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HaV is a dsDNA virus that is specifically infectious to the HAB-causing microalga, Heterosigma akashiwo (Raphidophyceae). Previous study found that the impact of HaV-infection on the population dynamics of H. akashiwo was both quantitative and qualitative. In the present study, we surveyed a H. akashiwo bloom in Hiroshima Bay over five weeks in early summer 2000, and cross-assayed the 65 axenic clones of HaV and 90 axenic host clones isolated during the survey. Based on the infection specificity and virus sensitivity patterns revealed by the cross-assay, HaV isolates and host isolates were divided into 7 and 3 types, respectively, by means of the neighbor-joining method. The results clearly show that different types of HaV and H. akashiwo coexist in the natural environment. Through the survey, the host type composition dynamically fluctuated, and each type of viruses showed different titer dynamics. Thus, we conclude that a complex relationship occurs between HaV and H. akashiwo, controlling their population dynamics. This study was supported by the Industrial Technology Research Grant Program in 01 from the NEDO of Japan.