Test procedures for measuring the (sub)chronic effects of chemicals on the freshwater cyclopoid Eucyclops serrulatus

The purpose of this study has been to describe test procedures for measuring the (sub)chronic effects of chemicals on the freshwater cyclopoid Eucyclops serrulatus. To this end we have adapted the setting of the standard full life-cycle protocol of the marine harpacticoid A. tenuiremis to E. serrulatus. We have tested the effects of 4 different diets, two temperatures and two rearing volumes on the survival, development, reproduction and population growth rates of this species. Our results have highlighted that full life-cycle tests can be run using 2 mL-glass vials, a diet consisting of a mixture of living cells of Chlorella sorokiniana and Scenedesmus quadricauda, at either 25 °C (test duration: 42 days) or 18 °C (test duration: 51 days). However, the best performance in terms of survival, development, reproducibility and population growth rates with this species was obtained at 18 °C, albeit with significantly longer test duration. Subchronic tests in 2 mL-glass vials with the mixture microalgal diet at both temperatures are available options if considered appropriate for the objectives of a given study. In particular, developmental tests from nauplius to copepodid may profitably be performed in about 11 days at 18 °C and in 6 days at 25 °C. Under the same test conditions, subchronic tests from copepodid to adult may be run in 19 days at 18 °C and in 16 days at 25 °C.