Sublethal effects of cadmium on auditory structure and function in fathead minnows (Pimephales promelas)

Aquatic ecosystems are threatened by environmental contaminants, and many heavy metals can influence both the structure and function of sense organs in fishes. The use of these senses is vital to the survival and reproductive success of fish and therefore affects the health of the ecosystem as a whole. The current study examines the effects of cadmium on auditory structure and function in the fathead minnow (Pimephales promelas). In the laboratory, fish were exposed for 96 h to a range of cadmium concentrations and both hearing sensitivity and hair cell morphology were quantified. While hair cell numbers were unaffected, cadmium caused an increase in auditory threshold, with a critical range for toxic effects of cadmium estimated at 2.1-2.9 µg L(-1). Cadmium exposure also caused a decrease in response latency at higher cadmium concentrations. The current study demonstrates the sublethal effects of cadmium on fish sensory function while also pointing to the need for more careful interpretation of cadmium impacts on aquatic populations.