EFFECTS OF TEMPERATURE AND SALINITY ON THE GROWTH OF THE RED-TIDE-FLAGELLATES HETEROCAPSA-CIRCULARISQUAMA (DINOPHYCEAE) AND CHATTONELLA-VERRUCULOSA (RAPHIDOPHYCEAE)

Growth responses of the red tide flagellates, Heterocapsa circularisqu ama (Dinophyceae) and Chattonella verruculosa (Raphidophyceae), were e xamined with 36 different combinations of temperature (5-30 degrees C) and salinity (10-35 PSU). Heterocapsa circularisquama did not grow at or below a temperature of 10 degrees C. The maximum growth rate of H. circularisquama (1.3 divisions day(-1)) was obtained with a combinatio n of 30 degrees C and 30 PSU. In contrast, C.verruculosa did not grow at 10 PSU and at temperatures of 25 degrees C or more. The maximum gro wth rate of C.verruculosa (1.74 divisions day(-1)) was obtained with a combination of 15 degrees C and 25 PSU. A significant temperature-sal inity interaction on growth was found by factorial analysis. Based on the physiological characteristics obtained in the present study, these novel flagellates have a potential for future outbreaks of red tides in previously unaffected waters.