[Effects of nutrients nitrogen and phosphorus on Heterosigma akashiwo growth]

The study showed that the relationships between the specific growth rate (up) of Heterosigma akashiwo and the concentrations of nutrients nitrogen and phosphorus in water body accorded with Monod equation. H. akashiwo started to grow when the concentration of NO3(-)-N was higher than 7.5 mg x L(-1), and the specific growth rate (micro) of the algae was proportional to the concentration of NO3(-)-N between 3.75 to approximately 75 mg x L(-1). The maximum growth rate of H. akashiwo (micro/m-n) was 0.3475 x d(-1), and the half saturated constant (Ks-n) was 18.91 mg x L(-1). The specific growth rate of the alga was proportional to the concentration of PO4-P between 0 to approximately 1.0 mg x L(-1).The maximum growth rate of H. akashiwo ( microm-p) was 0.3024 x d(-1), and Ks-n was 0.4086 mg x L(-1). The most suitable growth conditions for H. akashiwo were 37.5 to approximately 225.0 mg x L(-1) NO3(-)-N, 5.0 to approximately 50.0 mg x L(-1) PO4-P, and N/P 25.