抄録
The aquatic oligochaete, Aeolosoma hemprichi, was inoculated into two continuous culture media containing constant numbers of bacteria and bacteria and a protozoa, Cyclidium sp.. The oligochaete was established successfully, and its population density maintained a steady state in both cultures even though the maximum specific growth rate was considerably lower than the dilution rate of the culture media. In both cultures a large number or bacteria formed flocs. Many oligochaetes attached to the larger flocs. Since the larger flocs were rarely washed out, they prevented the oligochaete from being washed out from the culture vessels. The larger flocs were broken up by the shear stress of aeration as well as by the feeding action of the oligochaete. Thus due to the balance of formation and degradation, the floc mass maintained a steady state. We suggested that the establishment and the maintenance of a steady state in the population density of the oligochaete depended on the formation and maintenance of the bacterial flocs. Additionally, it was proved that the population density or the oligochaete increased when protozoa were present as the protozoa accelerated the enlargement of the flocs to which the oligochaete attached.
