Meeting Abstract
Polar bears rely on sea ice for reproductive behaviors and food, and progressive sea ice decline has had severe impacts on the health and reproductive success of polar bears. This environmental stressor may be causing physiological changes that can be measured via endocrine function: cortisol is an energy mobilizing hormone and indicative of stress, and testosterone (males), and estradiol and progesterone (females) can be used to measure reproductive function. While fecal and serum samples have previously been used, hair may be a useful alternative, being less invasive to obtain, and theoretically providing a long-term average of the previous year’s hair growth, thus being unaffected by capture stress. Hair and serum samples were collected from free-ranging polar bears, validated, and analyzed for stress and reproductive hormones via radioimmunoassay. We found that hair and serum estradiol concentrations were positively related, as were hair progesterone and estradiol, progesterone and cortisol, and testosterone and cortisol. These results suggest that hair may be a good predictor of serum estradiol concentrations, and that there are significant interactions among stress and reproductive functions that are measurable in hair. Hair might therefore be a useful tool for understanding the effects of sea ice decline on reproductive function and the role of stress in these changes, thereby playing a critical role in conservation efforts for the species.
