THE EFFECTS OF PHYSICAL TREATMENT ON FRESHWATER RED TIDE FORMING DINOFLAGELLLATE (PERIDINIUM): EXPERIMENTAL STUDY

Abstract

We carried out experimental study investigating the effects of physical treatment on dinoflagellate (Peridinium bipes) in order to develop measure to prevent freshwater red tide in reservoirs. Surface water in the reservoir occurring freshwater red tide was sampled for the physical treatments. We found that physical treatment caused cessation of swimming of P. bipes and subsequently effects on water quality and plankton composition. Immediately after physical treatment, almost of all cells of P. bipes stopped swimming behavior. However, one day after treatment, about 70% of cells restarted swimming. This ratio maintained 12 day after the treatment. Settlement of stopping cells led decrease in concentration of Chla and SS. Considering these effects, we discussed mechanism of effects of physical treatment on Peridinium dynamics and counter measure preventing freshwater red tide.