Chronic effects of p-nonylphenol on survival and reproduction of Daphnia galeata:: Multigenerational life table experiment

The chronic effect of p-nonylphenol on survival and reproduction for two generations of the freshwater cladoceran Daphnia galeata was examined by life table experiments. The effects on survival and reproduction were used as the intrinsic rate of natural increase, r, with the Euler-Lotka equation and were analyzed with a simple mathematical model (a power function). The population-level EC50, the concentration of a substance that reduces the intrinsic rate of natural increase by 50%, was estimated as 65.2 mug/L for the first generation and 81.5 mug/L for the second generation. No transgenerational effect that reinforces adverse responses in the offspring generation has been detected. From a 48-h immobility test an acute LC50 was estimated to be 60.8 mug/L. The acute LC50 is a good indicator of the chronic population-level effects of this chemical to this species. (C) 2002 Wiley Periodicals, Inc.