Prediction of fecundity in chronic toxicity tests on Daphnia magna

The present study deals with the analysis of fecundity in Daphnia magna in chronic toxicity tests. Regression models were used to assess the possibility of predicting fecundity values over the long term on the basis of growth values recorded early in the toxicity test. The results based on data from toxicity tests with pyridine, cadmium and chromium (the last at two different food levels), indicate that such predictions are practicable, since the relationship between growth and fecundity is strong and robust under the experimental conditions employed. Damaging effects of toxicants on fecundity over 21 d (the usual length of the Daphnia magna chronic toxicity tests) and/or longer, can be derived from body length recorded in shorter exposure to toxicants.