ECOSYSTEM STRUCTURE OF A BOILING SPRING WITH HIGH BACTERIAL PRODUCTION ON MT TATEYAMA, JAPAN

The ecosystem structure of a boiling hot spring with high bacterial pr oduction in the Jigokudani Valley of Mt. Tateyama, Japan, was studied. The spring is about 2 m diameter, and its bottom is rather flat and l ess than 50 cm deep. The spring has a partition shelf at about 20 cm d epth over the whole area. The spring water was thick, milky and turbid above the shelf because of a high concentration of the silica-sulfur particles, with a high density of chemosynthetic sulfur bacteria attac hed. Near the surface of the spring, the bacterioplankton had populati on densities in the order of 10(7) cells ml(-1). This spring has a uni que structure similar to a continuous culture system. The spring has a partitioning shelf at the intermediate depth, and the shelf vents hav e functions as a pumping regulator and agitator to supply the heated u nderground water from beneath the shelf. This space functions as a med ium reservoir. The geothermy supplies physical energy for the spring.