赤潮鞭毛藻に関する研究-II

五ケ所湾に出現したHeterosigma inlandicaについて

抄録

To find the reason for outbreak of red tide, physiological characteristics of causative planktons have been studied. Present paper deals with Heterosigma inlandica n. sp. which caused red tide in Gokasho bay, Shima peninsula, 1966.
Heterosigma inlandica was obtained in axenic culture by micropipette washings. The organism is wide range euryhaline. The optimal pH range was 8.5 to 9.0, the growth decreased with changing of pH. In the axenic culture, H. inlandica needs vitamin B₁₂ for growth. The addition of other vitamins does not increase growth further. The pattern of specificity is similar to that of Ochromonas malhamensis. All the analogues containing henzimidazole can replace B₁₂•H. inlandica prefers NO₃ as nitrogen source. Urea and NH₄ in low concentration, glutamine are good N sources. Uric acid, asparagine and arginine are also utilized but growth is less abundant. Inorganic and organic phosphates are utilized. Three purines (xanthine, hypoxanthine and guanine), and three pyrimidines (uracil, cytosine and thymine) increase growth in the presence of vitamin B₁₂. From these results, the primary cause of the great increase of H. inlandica was discussed.