天然海水中における付着珪藻10種の増殖速度

抄録

The cell division rates of ten species of attaching diatoms isolated from Ago Bay were measured on the bottom of the culture vessel with running nutrient-poor natural seawater under the illumination of 4000 lx with a dark/light cycle of 10/14 hours at ca. 19°C. The exchange rate of running seawater through the culture vesel affected the cell division rate of attaching diatom. At ca. 4-5 day^-1 of exchange rate of seawater, the cell division rates were as follows: Cymbella sp., 0.57 day^-1, Stauroneis sp., 0.49; Gyrosigma sp., 0.80; Navicula sp., 0.57; Nitzschia closterium, 1.60; Cocconeis scutellum, 0.86; Melosira sp., 0.27; Grammatophora marina, 0.46; Trigoium formosum, 0.29, and Gomphonema sp., 0.34. The cell division rates obtained in running nutrient-poor seawater corresponded to those in nutrient-enriched medium. The cell division rates of former six species which showed gliding movement and did not from their or colony, were larger than those of the latter four species which formed their chain or colony and adhered tightly to the substrate. This result may suggest that the latter type diatom competes with each other for light, nutrients, space and so on more severely than the former.