Abstract
Chronic effect of sulfuric acid on survival and reproduction of a freshwater cladoceran Daphnia galeata was estimated with the semi-static method. In order to estimate the population-level effect, adverse responses of survival and reproduction were converted to reductions of the intrinsic rate of naltural increase r with the Euler-Lotka equation. The population-level ECSO, which is defined as the sulfuric acid concentration that reduces r by 50 percent, was estimated as 11.4 mg/L or pH 5.0. The population growth rate exhibited gradual impairments at considerably larger pH than that inducing acule lethal effect to Daphnia.
