Comparative sensitivity and mechanisms of action of endemic fish species to environmental endocrine disruptors

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Aquatic systems are under threat from contaminants, as well as from increasing temperature and decreasing levels of oxygen (hypoxia) from global climate change and release of municipal and industrial effluents. Coastal and inland fish are exposed to contaminants from increasing urbanization and industrialization. Endocrine disruptors are environmental chemicals that affect fish by altering the normal functioning of their hormone systems which control reproduction, offspring development and growth. My proposal seeks to improve understanding of why some fish are more sensitive to environmental endocrine disruptors, and how changes in environmental conditions (e.g., temperature and hypoxia) affect the interaction of the contaminants within the fish. We will undertake studies on two Canadian fish species, the estuarine mummichog (Fundulus heteroclitus) of the east coast and the freshwater fathead minnow (Pimephales promelas) of the central region. Both species are somewhat resilient to environmental changes in temperature and dissolved oxygen, making them good model species. We will focus on the effects of synthetic estrogens which enter our waterways via sewage (from women taking birth control pills) and synthetic androgens from agricultural operations (from meat production). We hope to determine the relative sensitivity to endocrine disruptors of these important species in terms of their gonadal and offspring development in increasingly vulnerable environments. Of particular interest are the physiological processes by which the fish metabolize and clear (remove) the contaminants, respond via differences in receptor affinity to the contaminants in different tissues, and the resilience of their critical gonadal maturation process to exposure to external endocrine disruptors. Overall, studies in my laboratory seek to understand the mechanisms by which endocrine disruptors affect endocrine status, the factors affecting such, and the consequences of this impaired endocrine status on reproduction, growth and development in fish. By better understanding mechanisms of action in different species, we will be better able to make predictions of how to improve aquatic systems management to protect fish health.