ABSTRACT: Gymnodinium galatheanum Braarud shows optimum growth (0.57 d^-1) at 20 to 24*C and 24 o/oo S, within a temperature/salinity range of 7 to 24*C and 10 to 34 o/oo S, respectively. The growth rate is significantly affected by temperature and salinity, but no temperature-salinity interaction is found. No photoinhibition is found below 500 umol photons m^-2 s^-1. Optimum irradiance for growth is ~120 umol m^-2 s^-1, while the optimum for the growth-relevant chl a-normalized C fixation rate is >500 umol m^-2 s^-1. This difference in optimum irradiance for the growth and photosynthetic rate is related to a decrease in the cellular chl a/carbon ratio with increasing irradiance. Carbon, nitrogen and phosphorus contents per cell are significantly affected by temperature, salinity and irradiance. The high and low P/C and N/P ratios, respectively, for nutrient saturated cells indicate that G. galatheanum has a large storage capacity for phosphorus.

KEY WORDS: Gymnodinium galatheanum . Toxic dinoflagellate . Growth ecology . Chemical composition

Published in MEPS Vol. 136 (1996) on June 6
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996