EFFECTS OF COPPER ON LIFE-HISTORY TRAITS OF DAPHNIA-PULEX AND BOSMINA-LONGIROSTRIS

Daphnia magna, and to a lesser extent D. pulex, are commonly used in standardised laboratory toxicity tests. Neither of these species is common in lakes inhabited by fish which is explained by strong predation pressure by fish. They also exhibit different life-history strategies compared to lake-inhabiting species like Bosmina. Daphnids produce many small (relative to adult size) juveniles whereas the opposite is true for Bosmina. The large neonate size allows an earlier maturation of Bosmina compared to Daphnia. In the present study the effects of copper (10-30 ppb) on life-history traits of D. pulex and B. longirostris were compared. The only significant copper effect on D. pulex was a minor delay of maturation. On the contrary, negative impacts of the same copper concentrations were found on the survival, growth, maturation age, and fecundity of B. longirostris. The population growth rate (r) of B. longirostris decreased with increasing copper concentration. The study showed that B. longirostris was about two times more sensitive to copper stress than D. pulex.