The effect of food concentration on population fluctuation and productivity of Asplanchna brightwelli

The influences of food concentration on populat ion fluctuation and production of cannibalism, Asplanchna brightwelli were studied. It was found that, in the cumulative culture , the population dynamic of A. brightwelli fed on Paramecium of concentrat ions ranging from 100 to 400cell#mL- 1 displayed typical 0s0 curves in the course of the experiment , and the relationship between the population persistence production and standing crop were conic function. With reference to food density experiments, there were the highest value of maximum sustained yield( MSY) , capacity ( K) , average production or intrinsic rates of increase of population under 300 Paramecium#mL - 1 in the whole diet concentration, which were 6. 4indiv#mL - 1#d - 1 ( 355mg#L - 1 ) , 13. 7ind# L- 1( 760. 6mg#L- 1) , 55 mg#L- 1 and 1. 4496( d- 1) respectively. In the range of 100- 300cell#mL- 1, the MSY, critical standing crops and the time arrival to MSY or K increased with increment of diet concentration, whereas the above ment ioned indexes decreased in 400cell#mL- 1 of food density. Fed on Paramecium, the value of food rat ion of rotifers changed 146% ~ 707% of body weight , with average 390%; food coeff icient was 19. 8 - 91. 7.