Effect of linear alkylbenzene sulfonate on population growth of Daphnia galeata: A life table evaluation

The chronic effect of linear alkylbenzene sulfonate (LAS(12)) on a daphnid species (Daphnia galeata) was examined by the life table experiment. The es timated responses in the intrinsic rate of population growth r were analyze d with two alternate concentration-response functions, i.e., the power func tion and the quadratic function. Based on the best-fit power function model with biases corrected by the jackknife procedure, the population-level EC5 0, which is defined as the concentration of chemicals that reduces the popu lation growth rate (the intrinsic rate of natural increase) by 50%, was est imated as 2.5 mg/L. The 48-h acute immobility test yielded EC50 of 4.6 mg/L . The population-level effect of LAS(12) on this test species is considerab ly more sensitive than the acute lethal effects to neonates. (C) 2001 by Jo hn Wiley & Sons, Inc.