EFFECTS OF PHYSIOLOGICAL FACTORS ON MORPHOLOGY AND MOTILITY OF CHATTONELLA-ANTIQUA (RAPHIDOPHYCEAE)

The effects of temperature, salinity and light intensity on morphology and motility of Chattonella antiqua were investigated. The m orphology (shape) and motility of cells were strongly affected by varied temperatures. At 20-25 degrees C more than 90% cells in logarithmic phase were spindle shaped, whereas all the cells became spherical at 10 and 30 degrees C within 4 and 6 days, respectively. The best motility was found at 25 degrees C. Motility at 20 degrees C was as good as at 25 degrees C in logarithmic phase, but was poor in stationary phase. The number of spindle and motile cells was highest at 25-35 parts per thousand and was less at lower salinities. Light intensity did not influence morphology under the range of light intensities tested (20- 180 mu E m(-2) s(-1)). Good motility was observed at 60-180 mu E m(-2) s(-1). A comparable growth study of two strains of C. antiqua (YT84 and KA78) was also carried out. Both strains gave similar results, but strain YT84 showed slightly faster growth than KA78. Optimal growth of both strains occurred under a narrow range of temperatures (20-25 degrees C) and broad ranges of salinities (25-40 parts per thousand) and light intensities (60-180 mu E m(-2) s(-1)). Growth did not occur at temperatures below 15 degrees C or above 30 degrees C.