Copper exposure and the degeneration of olfactory receptors in rainbow trout (Oncorhynchus mykiss)

Abstract

Sublethal concentrations of copper in water cause the degeneration of olfactory receptors in rainbow trout (Oncorhynchus mykiss). Receptor cell loss has been correlated to the loss of olfaction in fish and may cause difficulties in olfactory mediated behaviors such as migration. This study investigated the effects of three levels of copper (100, 75 and 50 mg L^?1) on the olfactory epithelium of rainbow trout. Twenty fish randomly allocated between three exposure groups and one control were exposed for 24 hours under static renewal conditions. Light and scanning electron microscopic observations of olfactory tissue were taken to determine the extent of degeneration of receptors. In addition, levels of copper and zinc in the brain tissues were analyzed to determine if the olfactory route was a significant route of copper exposure and transfer to fish brain tissue. Results indicate that degeneration of receptors is related to the concentration of copper. Levels of copper in brain were found to be below detection of the instrument. Levels of zinc were extremely variable ranging from 52 to 132 ng zinc g^?1 brain tissue.