Sex differences in the acute and long-term toxicity of copper, chromium and zinc to Daphnia magna

Abstract

The acute toxicity of 3 metal irons, copper (II) , chromium (IV) and zinc (II) and the long-term toxicity (21-day exposure) of copper were evaluated in both male and female Daphnia magna (Cladocera, Branchiopoda) to investigate sex differences. Prior to toxicity tests, environmental conditions, in which daphnids produced male neonates at a higher ratio and with predictable timing, were examined and a practical method to obtain males was determined. Male and female neonates were obtained from female parents exposed to a shorter photoperiod and reduced food supply, and were used for the acute and long-term toxicity tests. There was no significant difference between the male and female 48hr- EC₅₀ values in the acute toxicity test or mortality, fecundity or growth parameters in the long-term toxicity test. It is therefore considered that there is no large sex difference in the acute toxicity of copper, chromium, zinc and in the long-term toxicity of copper.