珪藻Ｃｙｌｉｎｄｒｏｔｈｅｃａ ｃｌｏｓｔｅｒｉｕｍ（ＥＨＲＥＮＢＥＲＧ）Ｒｅｉｍａｎｎ ｅｔ Ｌｅｗｉｎの増殖に及ぼす環境諸要因の影響

Abstract

The study was undertaken in order to elucidate a variety of factors affecting the propagation of Cylindrotheca closterium found on the nori nets. The following results were obtained: 1) The species showed a tendency to increase with the fall of temperature in the monthly changes of cell numbers. 2) The range of the optimal temperature for good growth was 10-25°C. 3) The optimal pH was 7.3 to 9.0 at 10°C and 7.0 to 9.0 at 15°C and 20°C. 4) The optimal light intensity was above 2, 000 1x at 10°C, 3, 000 1x at 15°C and 2, 000 1x at 20°C. 5) The species grew optimally under the value of chlorinity, 14.6 to 22.0‰ at 10°C, 13.5 to 22.0‰ at 15°C and 11.0 to 22.0‰ at 20°C. 6) The effect of each nutrient on the propagation, inorganic nitrogen, silicate and borate were necessary for the propagation, and especially the first and third compounds were essential. 7) The amino acids released from the nori fronds were utilized for the propagation as the nitrogen source for lack of inorganic nitrogen. 8) The general consideration could be made on the propagation factors in the nori cultivation ground. The species grew actively by mainly utilizing inorganic nitrogen at the beginning of cultivation and grew continuously by utilizing the amino acids released from the nori fronds after the middle period.