Journal of The School of Marine Science and Technology,Vol.4 No.3
Some of Observations of the Population Growth Mechanism in Early Stage of the Rotifer Brachionus plicatilis Culture
Toshio SAITO, Fumito OOMORI, and Shuugo WATABE
Abstract
Population growth pattern of the rotifer Brachionus plicatilis was studied by evaluating the lag phase in three
samples with varying density (0.6，3 and 6 ind ml-1) and each containing 5 ml of culture medium. The cultures
showed a shorter lag phase in the samples with higher density.This result suggests that the physiology and metabolic
activity of the rotifers were influenced by the density of the samples. Influence of output products (egestion and
excretion)of rotifers on population growth was further examined under the present investigation.For this purpose,
rotifers were cultured in filtered medium of different concentrations (25％, 50％, 75％ and 100％) along with a
standard (0％ filtered medium). After a fixed time lag, it was noticed that the number of rotifers in the filtered
medium was significantly higher (p＜0.05)than that of the standard.Such result clearly indicates inducing effect of
the output product on the exponential growth phase of the rotifer population.