Effects of temperature and organic and inorganic nutrients on the growth of Chattonella marina (Raphidophyceae) from the Daya Bay, South China Sea

The effects of temperature and different forms of nutrients on Chattonella marina growth have been investigated in strains isolated from the Daya Bay, the South China Sea. The strain of C. marina preferred high temperatures, with an optimal temperature of 25°C, and 18°C was the minimum for its survival. Higher cell number and growth rate were obtained in high nitrogen and phosphorus concentrations (500 μg/L, 74 μg/L) than under nutrient limitation. Nitrogen influenced the growth most, as the specific growth rate and maximum cell density were lower in nitrogenlimited cultures than noted under phosphorus limitation or under limitation from both. C. marina was capable of using many kinds of organic nitrogen sources including L-serine (L-Ser), glycine (Gly), alanine (Ala), L-threonine (L-Thr), glutamic acid (Glu) and urea, but could not utilize uric acid. Various forms of organic phosphorus compound such as glucose-6-phosphate (G6P), sodium glycerophosphate (GYP), adenosine triphosphate (ATP), adenosine monophosphate (AMP), cytidine monophosphate (CMP), guanosine monophosphate (GMP), uridine monophosphate (UMP), 4-nitrophenylphosphate (NPP) and triethyl phosphate (TEP) supported the growth as well. Algal cells had the ability to sustain growth under nitrogen- and/or phosphorus-free conditions particularly under phosphorus depleted condition. These results led to the hypothesis that high loading of nitrogen has played an important role in frequent C. marina blooms in the past decade, and its capability for utilization of diverse forms of organic nutrients and growth in low nutrient conditions make this species a likely recurrent dominant in the Daya Bay phytoplankton assemblages, visible as more frequent blooms.