Although toxic chemicals can cause dramatic fish kills, the large majority of exposures in aquatic habitats are sublethal. Environmental health research is therefore focused on how contaminants affect the physiology of fish and other species, including the normal function of the nervous, immune, endocrine, and reproductive systems. These changes are then linked to the survival and reproductive success of individuals, the growth and productivity of populations, and interactions among species within a community.
The neurotoxicity of copper, a common water pollutant, is a case example. As recent research by the Ecotoxicology Program has shown, copper is directly toxic to the salmon olfactory system at very low exposure concentrations. Unable to smell, copper-exposed juvenile salmon become unresponsive to chemical signals in their environment, including cues indicating the close proximity of a predator. When they fail to take evasive action, they are much more likely to be captured and killed by predators than are their counterparts with a working sense of smell. These nuanced but consequential effects on salmon sensory biology and behavior emphasize the importance of "eco" in ecotoxicology.
NOAA Coastal Services Center, National Coastal Storms Program
University of Washington, School of Aquatic and Fisheries Sciences
Oregon State University, Department of Environmental and Molecular Toxicology
McIntyre, J.K., Baldwin, D.H., Beauchamp, D.A., and Scholz, N.L. 2012. Low-level copper exposures increase the visibility and vulnerability of juvenile coho salmon to cutthroat trout predators. Ecological Applications, 22:1460-1471.
Tilton, F.A, Tilton, S.C., Beyer, R.P., Bammler, T.K., Beyer, R.P., Stapleton, P.L., Scholz, N.L., and Gallagher, E.P. 2011. Transcriptional impact of organophosphate and metal mixtures on olfaction: Copper dominates the chlorpyrifos-induced response in adult zebrafish. Aquatic Toxicology, 102:205-215.
Baldwin, D.H., Tatara, C.P., and Scholz, N.L. 2011. Copper-induced olfactory toxicity in salmon and steelhead: extrapolation across species and rearing environments. Aquatic Toxicology, 101:295-297
Tierney, K.B., Baldwin, D.H., Hara, T.J., Ross, P.S., Scholz, N.L., and Kennedy, C.J. 2010. Olfactory toxicity in fishes. Aquatic Toxicology, 96:2-26.
Linbo, T.L., Baldwin, D.H., McIntyre, J.K., and Scholz, N.L. 2009. Effects of water hardness, alkalinity, and dissolved organic carbon on the toxicity of copper to the lateral line of developing fish. Environmental Toxicology and Chemistry, 28:1455-1461.
McIntyre, J.K., Baldwin, D.H., Meador, J.P., and Scholz, N.L. 2008. Chemosensory deprivation in juvenile coho salmon exposed to dissolved copper under varying water chemistry conditions. Environmental Science and Technology, 42:1352-1358
Hecht, S.A., Baldwin, D.H., Mebane, C.A., Hawkes, T., Gross, S.J., and Scholz, N.L. 2007. An overview of sensory effects on juvenile salmonids exposed to dissolved copper: Applying a benchmark concentration approach to evaluate sublethal neurobehavioral toxicity. NOAA Technical Memorandum NMFS-NWFSC-83, 39 p.
Sandahl, J.F., Baldwin, D.H., Jenkins, J.J., and Scholz, N.L. 2007. A sensory system at the interface between urban stormwater runoff and salmon survival. Environmental Science and Technology, 41:2998-3004.
Linbo, T.L., Stehr, C.M., Incardona, J.P., and Scholz, N.L. 2006. Dissolved copper triggers cell death in the peripheral mechanosensory system of larval fish. Environmental Toxicology and Chemistry, 25:597-603.
Baldwin, D.H. and Scholz, N.L. 2005. The electro-olfactogram: an in vivo measure of peripheral olfactory function and sublethal neurotoxicity in fish. In: Techniques in Aquatic Toxicology, Volume 2. GK Ostrander (ed.), CRC Press, Inc. Boca Raton, FL. pp. 257-276.
Baldwin, D.H., Sandahl, J.F., Labenia, J.S., and Scholz, N.L. 2003. Sublethal effects of copper on coho salmon: impacts on non-overlapping receptor populations in the peripheral olfactory nervous system. Environmental Toxicology and Chemistry, 22:2266-2274.