抄録
The present report has been written in the hope to give a preliminary account on the hodrobiological feature of Uranouchi Bay. The data so far obtained shows that Uranouchi Eay behaves like a salt lake though it communieates with outer sea through a narrow and shallow canal The development of thermal and chemical stratifications in this bay are very prominent, the thermal stratification being direct from January to September, and indiroct from October to Febru ?? ry. The direct stratification of dissolved oxygen is set in April when the water temprature is 15.0°C. Such a stratification is kept so long as the upper layer shows low salinity as it makes the stratification stable. It is, however, often disturbed when the density of surface water rises due to the strong evaporation of summer days, which causes the vertical circulation of water.
The saturation percentage of oxygen ranged between 15.7% (August, 1944) and 160.6% (June 1943), the latter value probably being due to Chactoceros boreals which then vegetated. The bulk of the plankton is usu lly composed of Diatoms such as Chaetoceros Schuttii, Ch, decipiens, Ch. dydymus, Ch. diadema, Rhizosolenia hebetata, Rhizo, acuminata, Thatrix. Fraucnfddii, and Nitzschia seriata. The zooplankton which is usually of second importance in quantity, consisted of many Copepods, Euadne, Podon, Penilia, Ceratium fusus, and Noctilaca scintillans. Of zooplankton it was found that Creseis and Bolipnopsis appeared in great abundance during Summer and Autumn respectively.
