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dc.contributor.authorLian, Marianne
dc.date.accessioned2021-10-21T23:53:46Z
dc.date.available2021-10-21T23:53:46Z
dc.date.issued2020-08
dc.identifier.urihttp://hdl.handle.net/11122/12309
dc.descriptionDissertation (Ph.D.) University of Alaska Fairbanks, 2020en_US
dc.description.abstractThis 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 during foraging. However, the relatively high [THg] found in some SSL cause concern for sequestration of Se due to its high binding affinity to Hg, and subsequently decreased antioxidant capacity (Se-dependent glutathione peroxidase (GPx)). I found a significant negative relationship between lipid peroxidation and [TSe], suggesting the potential for decreased antioxidant protection from Se. There were also significant associations between increased GPx activity and lipid peroxidation, possibly protecting pups with relatively high [THg] and low TSe:THg molar ratios. In Chapter 4 I repeatedly evaluated live-stranded HS pups admitted to The Marine Mammal Center, using weekly clinical and behavior assessments, which were analyzed for associations with [THg]. There was a significant association between [THg] in hair and/or blood and decreased response to tactile stimulation, less movement and longer stays in rehabilitation. These findings will help us better assess similar [THg] in hair and blood of SSL in Alaska that we currently study as well as other pinnipeds. In summary, this dissertation confirms the potential for adverse effects in two free-ranging species of pinnipeds exposed to MeHg⁺ in utero.en_US
dc.description.sponsorshipNOAA Award NA16NMF4390032, National Institute of General Medical Sciences of the National Institutes of Health Award Numbers UL1GM118991, TL4GM118992, or RL5GM118990, Ocean Peace Inc.en_US
dc.description.tableofcontentsChapter 1: Introduction -- 1.1 Mercury is a contaminant of global concern -- 1.2 Mercury concentrations in sentinel species -- 1.3 Steller sea lions, anesthesia and oxidative stress -- 1.4 Mercury and neurotoxicosis in harbor seals -- 1.5 A One Health perspective -- 1.6 References. Chapter 2: Field anesthesia of juvenile Steller sea lions (Eumetopias jubatus) using inhalation anesthesia -- 2.1 Abstract -- 2.2 Introduction -- 2.3 Methods -- 2.4 Results -- 2.5 Discussion -- 2.6 Conclusion -- 2.7 References -- 2.8 Figures -- 2.9 Tables. Chapter 3: Assessing oxidative stress in Steller sea lions (Eumetopias jubatus): Associations with mercury and selenium concentrations -- 3.1 Abstract -- 3.2 Introduction -- 3.3 Methods -- 3.4 Results -- 3.5 Discussion -- 3.6 Conclusion -- 3.7 References -- 3.8 Figures -- 3.9 Tables. Chapter 4: Assessment of clinical outcomes associated with mercury concentrations in harbor seal pups (Phoca vitulina richardii) in central California -- 4.1 Abstract -- 4.2 Introduction -- 4.3 Methods -- 4.4 Results -- 4.5 Discussion -- 4.6 Conclusion -- 4.7 References -- 4.8 Tables. Chapter 5: Conclusion -- 5.1 Overview -- 5.2 Lipid peroxidation associated with lower whole blood selenium -- 5.3 Mercury induced neurotoxicosis in harbor seal pups -- 5.4 Sex differences -- 5.5 Recommendations and conclusions -- 5.6 References -- Appendix.en_US
dc.language.isoen_USen_US
dc.subjectPinnipediaen_US
dc.subjectMercuryen_US
dc.subjectHeavy metal effecten_US
dc.subjectSteller's sea lionen_US
dc.subjectHarbor sealen_US
dc.subject.otherDoctor of Philosophy in Veterinary Biochemical Toxicology: Interdisciplinary Programen_US
dc.titleAssessing adverse effects of mercury in two pinniped speciesen_US
dc.typeDissertationen_US
dc.type.degreephden_US
dc.identifier.departmentDepartment of Chemistry and Biochemistryen_US
dc.contributor.chairO'Hara, Todd M.
dc.contributor.committeeRea, Lorrie D.
dc.contributor.committeeKuhn, Thomas B.
dc.contributor.committeeVan Wijngaarden, Edwin


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