Assessing adverse effects of mercury in two pinniped species

• Main Author: Lian, Marianne
• Other Authors: O'Hara, Todd M., Rea, Lorrie D., Kuhn, Thomas B., Van Wijngaarden, Edwin
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2020
• Subjects: Pinnipedia; Mercury; Heavy metal effect; Steller's sea lion; Harbor seal; Doctor of Philosophy in Veterinary Biochemical Toxicology: Interdisciplinary Program; Fairbanks; Pacific; harbor seal; Phoca vitulina; Alaska
• Online Access: http://hdl.handle.net/11122/12309

Dissertation (Ph.D.) University of Alaska Fairbanks, 2020 This dissertation studies measures of adverse effects in free-ranging pinnipeds associated with relatively high total mercury ([THg]) or monomethylmercury ([MeHg+]) concentrations, relatively low total selenium ([TSe]) concentrations and/or low TSe:THg molar ratios. Both the Steller sea lion (SSL, Eumetopias jubatus) and Pacific harbor seal (HS, Phoca vitulina richardii) inhabit coasts of the North Pacific, and are considered important sentinel species for One Health (environmental, animal and human health). Relatively high [THg] is reported for some animals in both species, causing concern for adverse effects especially in the developing fetus. Maternal piscivorous diet can expose the fetus to MeHg⁺ at a vulnerable developmental stage, with potential for adverse effects on several organ systems. This dissertation focused on two of these: nervous system development and function and oxidant/antioxidant homeostasis. In Chapter 2 I outlined capture and field anesthesia of free-ranging SSL. I found faster induction times for sevoflurane over isoflurane, with a significant interaction for anesthetist. Difference among the two agents is most likely attributed to the different chemical properties for these gases (blood solubility), whereas personal experience/comfort level most likely explains the differences between the human operators. Severe hypothermia was also documented, associated with the time of year, sex and duration of anesthetic event. There was an overall low mortality rate, and the protocols were effective for relatively safe field anesthesia of a large mammal. Chapter 3 assessed oxidant/antioxidant status and associations with [THg], [MeHg⁺], [TSe] and TSe:THg molar ratio in anesthetized free-ranging SSL pups. The anesthesia protocols described in Chapter 2 were used as a physiological stressor for measuring oxidative stress in SSL. Pinnipeds as diving mammals are naturally adapted with high antioxidant activity to survive long breath-holds ...