Effects of temperature and nutrient depletion and reintroduction on growth of Stephanodiscus hantzschii (Bacillariophyceae): implications for the blooming mechanism

Stephanodiscus hamtzschii was isolated from the Flan River, Korea, where it blooms annually during winter. The physiological responses of the diatom to the limitation and then reintroduction of nutrients (silicon, phosphorus, and nitrogen) were determined over a temperature range of 5-20 degrees C using short-term batch culture methods. For the control group, the maximum growth of S. hantzschii was highest at 10 degrees C. The growth of S. hantzschii under phosphorus limitation did not differ from that of the control group, but the diatom had high requirements for nitrogen and silicon for growth. After the reintroduction of nutrients, the maximum growth rate was highest for diatoms to which silicon had been reintroduced and second highest after the reintroduction of nitrogen. The results suggest that silicon is more important than other potentially limiting factors.