Effects of environmental and experimental design factors on culturing and toxicity testing ofCeriodaphnia dubia

Abstract

The U S. Environmental Protection Agency (EPA) has developed a 7-d toxicity test to evaluate effects of effluents on Ceriodaphnia dubia survival and reproduction. This study evaluated effects of laboratory culture and test procedures on Ceriodaphnia dubia survival and reproduction Parameters such as temperature, food concentration, beaker size, solution-renewal frequency, light quality, illumination, photoperiod, water type, and test organism age were evaluated to determine how these culture and test parameters affected individual culturing success and acceptability and reproducibility of toxicity test results. Test parameters proposed by the EPA were evaluated under controlled laboratory conditions by varying levels of individual environmental or experimental design parameters to determine an acceptable range of responses for survival and reproduction, both with and without a reference toxicant For those parameters not specified by the EPA (e.g, water hardness, light quality), commonly used ranges for those parameters were evaluated. Results provided a decision matrix of acceptable ranges for individual environmental and experimental design parameters that were used to optimize the test parameters for conducting 7-d effluent tests with Ceriodaphnia dubia Overall, of the studied test parameters, renewal frequency and photopenod were the primary factors affecting culture and toxicity test success In this study, the EPA restriction on Ceriodaphnia dubia age at test initiation was not critical, as long as all organisms were <24 h old and randomly distributed among the test concentrations