Concentration–response function of nitrite on survival, molting, and reproduction ofDaphnia similoides

We assessed the chronic toxicity of nitrite to Daphnia similoides and modeled the concentration–response function of nitrite on survival, molting, and reproduction. Survival time, number of molting, number of total offspring per female, number of broods per female, and number of offspring per brood decreased significantly with increasing NO2–N concentration during the 21-day experiment. The EC50s for number of total offspring per female, number of broods per female, and number of offspring per brood were 1.56, 3.99, and 1.71 mg L−1, respectively. A four-parameter logistic model was suitable for describing the concentration–response function and allows the estimation of reproduction indices of D. similoides at any given concentration of NO2–N.