Effects of nitrogen and phosphorus sources on the utilization and growth kinetics of the harmful dinoflagellate Cochlodinium polykrikoides isolated from Yatsushiro Sea, Japan

The effects of various inorganic and organic nitrogen (N) and phosphorus (P) sources on the utilization and growth kinetics of the harmful dinoflagellate Cochlodinium polykrikoides Margalef, which was isolated from the Yatsushiro Sea of Japan, were experimentally investigated. C. polykrikoides was able to grow actively with inorganic nitrogen compounds and to grow at a slower rate on organic nitrogen compounds, urea and amino acid glycine, as N-sources. On the other hand, this organism was able to effectively utilize a variety of both inorganic and organic phosphorus compounds as P sources. Specific maximum growth rate (μ′_m) and minimum cell quota (Q₀), which were obtained by semi-continuous growth experiments, were 0.48 day^-1 and 5.25 pmol cell^-1 under N-limited steady-state conditions, and 0.54 day^-1 and 0.37pmol cell^-1 under P-limited steady-state conditions. Based on the physiological characteristics obtained in the present study, C. polykrikoides may have advantages for species competition.