Chronic Effects of Cadmium and Zinc Mixtures on Flagfish (Jordanella floridae)

Flagfish were exposed to cadmium and zinc as individual metals and as mixtures (4.3-8.5 μg Cd/liter and 73.4-139 μg Zn/liter) through one complete life cycle in Lake Superior water (45 mg/liter total hardness). Cadmium and zinc did not act additively at sublethal concentrations when combined as mixtures; however, a joint action of the toxicants was indicated. Effects on survival showed that the toxicity of cadmium and zinc mixtures was little if any greater than the toxicity of zinc alone. Mechanisms of zinc toxicity in this test were similar to those in previous chronic tests of individual metals, indicating that the presence of cadmium did not influence the mode of action of zinc. Comparisons between metal residues in fish exposed to each individual metal or to the metal mixtures showed that the uptake of one metal was not influenced by the presence of the other.