ABSTRACT: The effect of temperature on the algicidal activity and stability of HaV (Heterosigma akashiwo virus), which infects the harmful bloom causing alga, H. akashiwo (Raphidophyceae), was determined by growing H. akashiwo culture inoculated with HaV under various conditions. Temperature and growth stage of the host culture are considered to be important factors determining the algicidal activity of HaV. The optimum temperature for the algicidal activity of HaV ranged from 20 to 25°C. Comparing the viral susceptibility of H. akashiwo strains and the algicidal activity of the HaV clones at different temperatures, both were suggested to be phenotypically diverse. Effect of temperature on the stability of HaV was also evaluated. HaV showed a relatively rapid decrease in infectious titer even when preserved at 5°C in the dark. The data is discussed in relation to the behavior of HaV in natural environments and the disintegration mechanism of H. akashiwo red tide.

KEY WORDS: HaV · Heterosigma akashiwo · Raphidophyceae · Harmful algal bloom · Red tide · Virus · Algicidal activity · Infectivity · Susceptibility · Temperature

Published in AME Vol. 15, No. 3 (1998) on August 31
ISSN: 0948-3055. Copyright © Inter-Research, Oldendorf/Luhe, 1998