Induction of cadmium tolerance in two clones of Daphnia magna straus.

1. The abilities of two different genotypes of Daphnia magna to develop cadmium resistance through physiological adaptation, after pre-exposure to sublethal concentrations of Cd, Zn and Cd/Zn mixtures, was investigated. 2. The induced elevation in cadmium tolerance was shown to be associated with an increase in the body concentration of metallothionein-like proteins. 3. The highly significant difference in acute responses to cadmium between the two clones reduced after pre-exposure. 4. Differences in cadmium tolerance were shown to be associated with differences in cadmium uptake.