Fundamental Studies on Physiology of Rotifer for its Mass Culture-IV

Nutritional Effect of Yeast on Population Growth of Rotifer

Abstract

The nutritional effect of caked yeast still living and of dried marine yeast on the rotifer, Brachionus plicatilis, was examined.
Experiments were performed by culturing many individuals in many test tubes, each containing two individuals in the experimental medium. From daily counts of eggs laid and surviving individuals, time intervals from hatching to 50% survival and to peak of fecundity, net reproduction rate, intrinsic rate of population increase and mean generation time were estimated.
The results obtained are summarized as follows.
1. Caked yeast still living, Rhodotorula sp. has less nutritional effect on the rotifer than that of the marine Chlorella. However, it seems to be somewhat effective as food for the rotifer.
2. Dried marine yeast itself has little nutritional effect on the rotifer. However, aerobical decomposition can increase the nutritional effect to some extent.
3. The marine yeast added to a diluted Chlorella suspension was very effective as supplementary food for the rotifer. Hence, yeast may be used most effectively as a sup-plementary food in the culture medium when sufficient phytoplankton can not be supplied to the rotifer.