Noninvasive biomarkers of compromised health from contaminant exposure in wildlife

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This proposal addresses a vital gap in knowledge about the relationship between exposure to environmental contaminants and biological indicators of stress in animals exposed to these pollutants. Our findings will support the foundation for rational scientific recommendations that can be understood by the general public, and which can inform regulatory policy. Environmental pollution is associated with a range of chronic diseases in humans, domestic animals, and wildlife. Using naturally exposed, native wildlife, supported by laboratory studies on experimental animals, I will study toxicological impacts of exposure to contaminants. We, as researchers and ecotoxicologists have often had negative effects on wildlife in our effort to improve their well being, ironically using lethal sampling to study impacts from contaminant exposure, adding substantially to the unacceptability of invasive research on wild species. Recently, toxicologists have recognized that we can learn much more by studying live animals, than we can by measuring pollutant residues in their tissues. My research program has focused on developing and validating biochemical responses in key species of wildlife to detect early contaminant related changes in body functions. These responses to contaminants, referred to as biomarkers, include immunological and hormonal responses, measures of oxidative stress, and antioxidant stores which protect again these damaging free radicals, or oxidative stress. Chronic stress will also compromise health and decrease disease resistance in affected animals through subtle, long-term costs. Stress in vertebrates is expressed through production of glucocorticoid (steroid) hormones such as cortisol, and has been measured in birds, fish, and mammals. Biological samples reflect these hormones levels integrated over minutes (blood and saliva), hours (urine & feces), or weeks to months (hair, feathers). In this proposal, I examine a suite of biomarkers in wild birds and mammals, as much as possible using minimally invasive techniques, to detect health effects in wildlife from contaminated sites. The assumption of most ecotoxicologists is that contaminant exposure imposes chronic stress. However, no studies have examined the relationship between contaminants, chronic stress, and biomarkers of pollutant exposure. I will investigate two major gaps in terrestrial ecotoxicology; 1) if and how we can use glucocorticoid (stress) hormones from hair or feathers as a non-invasive means of measuring chronic stress in animals exposed to contaminants. 2) which are the most consistent, reliable, sensitive, and preferably non-lethal biomarkers of toxicity across vertebrate species. This work will ultimately produce recommendations regarding which combination of the above biomarker responses, including chronic stress, are most predictive of pollution-driven risks to wildlife.