Effect of culture conditions and mother's age on the sensitivity of Daphnia magna Straus 1820 (Cladocera) neonates to hexavalent chromium.

Daphnia magna is a freshwater cladoceran used worldwide as test organism in aquatic toxicity assays. In Mexico there is a test protocol for this species; nevertheless, some aspects of the controlled neonate production, as well as the possible consequences of the reproducers' culture conditions on the response of neonates to the toxic substance, are not completely known. In the present study, we evaluated the effect of temperature and photoperiod on the acute toxicity of CrVI in D.