Acute toxicityand effect of Cd super(2+) on life table demography of Brachionus angularis and Keratella valga

The 24 h LC sub(50) values of Cd super(2+) to Brachionus angularis and Keratella valga at (25 plus or minus 1) degree C were determined by acute toxicity tests, and the effects of Cd super(2+) concentrations (7.0, 12.0, 20.4, 34.6, 58.8 and 100.0 mu g/L) on the life table demographic parameters including survivorship, fecundity, life expectancy at hatching, generation time, net reproductive rate, intrinsic rate of population increase and proportion of mictic offspring of B. angularis and K. valga both cultured at (25 plus or minus 1) degree C and with 1.0x10 super(6) cells/mL of Scenedesmus obliquus as the rotifers' food were studied by life table experiments. The results showed that the 24 h LC sub(50) values of Cd super(2+) to B. angularis and K. Valga were 95.5 and 231.9 mu g/L, respectively. Cd super(2+) concentration significantly affected the survivorships of B. angularis and K. valga (P