Steroid Hormone Variation and Stress Responses in Short-finned Pilot Whales

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Nowacek, Douglas P

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Wisse, Jillian

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2023-06-08T18:19:48Z

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2023

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Ecology

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As humans continue to introduce stressors into the marine environment, we are obligated to understand how our behaviors impact wildlife. For many cetacean populations, anthropogenic noise poses a significant conservation threat, but the ability to monitor these animals is constrained by their often-remote habitats and limited time at the surface. Researchers have developed innovative solutions to overcome these challenges, including the development of techniques that enable physiological sampling with minimal disturbance. As frontiers, these methods require careful development and validation before they can be used reliably in experimental studies. In this dissertation, I employ one of these innovative techniques, measuring steroid hormones in remote blubber biopsy samples, in short-finned pilot whales (Globicephala macrorhynchus). As modulators of reproduction and stress, steroid hormones provide information that is advantageous for wildlife monitoring. Because a validated method for measuring these compounds in short-finned pilot whale blubber did not yet exist, I adapted a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to simultaneously quantify 11 steroid hormones of interest. Before proceeding with its application, I tested its analytical and biological validity with blubber from three stranded short-finned pilot whales. Next, I applied the validated LC-MS/MS method to an archive of blubber biopsies, collected from free-ranging short-finned pilot whales in the Western North Atlantic. Leveraging the comprehensive nature of LC-MS/MS profiling, I investigated relationships between hormones and characterized steroid hormone profiles across demographic groups and seasons. In the fourth chapter, I conducted an acoustic response study, using the previously established methods to collect and quantify steroid hormones after exposure to simulated mid-frequency active sonar (MFAS). I modeled the responses of cortisol and cortisone over time to gain insight into steroid perfusion rates in cetacean blubber and asked whether demography contributed to these responses. Together, my results demonstrate the reliability of blubber for measuring steroid hormones and reflecting relevant physiological states, like stress and pregnancy. While LC-MS/MS enables extensive steroid measurement, it struggled to detect some steroids of interest in this matrix. This dissertation shows the relevance of multi-steroid profiling and offers reference points for baseline steroid concentrations in analytes relevant to behavior, reproduction, and stress. The observation of post-exposure stress responses confirms a relationship between noise and physiology in short-finned pilot whales and illustrates the ability of blubber sampling to be applied in this context.

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https://hdl.handle.net/10161/27575

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Ecology

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Endocrinology

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Conservation biology

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androgens

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anthropogenic noise

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blubber

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glucocorticoids

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pilot whales

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steroid hormones

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Steroid Hormone Variation and Stress Responses in Short-finned Pilot Whales

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Dissertation

duke.embargo.months

12

duke.embargo.release

2024-05-24T00:00:00Z

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