FEEDING RATE OF BRACHIONUS-PLICATILIS MULLER,O.F. ON 2 TYPES OF FOOD DEPENDING ON AMBIENT-TEMPERATURE AND SALINITY

Feeding rates of Brachionus plicatilis were studied for two types of f ood - algae Monochrysis lutheri acid baker's yeast Saccharomyces cerev isae. The main regularities of changes in filtration rate and ration w ere studied in small culture volumes (1 mi) for adult amictic females depending on food concentration (1, 2, 4, 8 and 16 . 10(6) cells . ml( -1)), ambient temperature (16 and 26 degrees C), and salinity (5, 10, 15, 20, 25 and 30 ppt). B. plicatilis ration did not depend on the sal inity, but was largely determined by temperature and food concentratio n. It was found that at 16 and 26 degrees C the dependence of the inge stion rate (ration) on food concentration differed greatly. A hypothes is was suggested to explain this phenomenon. A critical concentration of both types of food at which the increase in the rotifer ration ceas ed is 4 . 10(6) cells . ml(-1). This is the minimum ''background'' foo d concentration for B. plicatilis mass cultivation. The average ration s measured at the concentration of M. lutheri and S. cerevisae of 4 . 10(6) cells . ml(-1) where 1.3 +/- 0.1 and 4.8 +/- 1.3 mu g dry weight . . ind(-1) . day(-1) at 26 degrees C and 0.54 +/- 0.1 and 1.9 mu g d. w. . ind(-1) . day(-1) at 16 degrees C, respectively. The rations obt ained in the laboratory were corrected for the conditions of rotifer c ommercial production in the open field in summer time. The correct val ues were 0.86 and 0.72 mu g d. w. . ind(-1) . day(-1) for algae and ye ast, respectively.