The effect of the nutrients on the growth of planktonic diatom Skeletonema costatum (Grev.) Cleve

The study dealt with the influence of nutrients on the growth of Skeletonema costatum, which was collected from the Yatsushiro Sea, Dokai Bay and Hibiki Nada, in the laboratory cultures. The cultures in the standard artificial medium (ASP12) and its variations without each nutrient showed that the growth of the three types decreased with the lack of inorganic nitrogen, silicate, borate and vitamin B12, and the tendency of the growth of the three types caused the same results essentially. But, the relation between the growth of the three types and the concentrations of the nitrate nitrogen and silicate in particular, among the nutrients, was found to show a remarkable variations in each type. Therefore, it was considered that the three types of S. costatum were ecotypes adapted to the difference of water quality at the collecting stations, and this produced the same results as the influence of chlorinity in the previous paper.