Metal-Specific Targeting of Olfactory Sensory Neuron Type: Implications for Risk Assessment

Olfaction mediates essential behaviours in fish such as foraging, predator avoidance, and reproductive behaviours. The olfactory epithelium (OE) binds to odourants in the water and transmits information to the brain for processing. The OE contains three olfactory sensory neuron (OSN) types; ciliated, microvillous, and crypt cells. By using electro-olfactography to measure olfactory acuity to cues that induce responses specific to one class of OSN, the targeted effects of toxicants can be studied. We exposed fathead minnows (Pimephales promelas) to either copper or nickel over a range of ecologically-relevant concentrations for 48 h. Exposure to copper at the highest concentration (20 μg/L) resulted in general olfactory impairment; however, exposure to low copper concentrations (5 and 10 μg/L) resulted in impairment specific to ciliated cells. Exposure to 25, 100, or 500 μg/L nickel resulted in impairment of microvillous but not ciliated cells. Comparison of these results to the effect of impairment on antipredator and feeding behaviours will give insight into what behaviours each OSN class mediates. This study is the first to show that copper and nickel target specific OSN classes known to mediate specific behaviours. This result can be used in ecological risk assessments to better predict sublethal effects of metals.