Doctor of Philosophy (PhD)
School of Renewable Natural Resources
On April 20th, 2010, the Deepwater Horizon oil rig blew out in the worst accidental marine oil spill in history and led to the severe oiling of the Northern Gulf of Mexico. The extensive shoreline oiling meant that terrestrial wildlife likely experienced both acute and chronic exposure to oil, as well as the enduring effects of habitat degradation and disturbance. The first major goal of this dissertation was to assess the long-term effects of the oil spill on the saltmarsh ecosystem through two terrestrial vertebrate species — the Seaside Sparrow (Ammospiza martima) and the marsh rice rat (Oryzomys palustris) — both of which have characteristics that make them valuable biological indicators, including the fact that the rice rat is the reservoir host of a zoonotic and pathogenic hantavirus: Bayou orthohantavirus (BAYV). This provided me with an opportunity to explore the role of a major anthropogenic disturbance in a zoonotic disease system, a subject of intensified interest during the current era of accelerated disease emergence. In Chapter 2, I used hepatic genetic markers in conjunction with measurements of toxins in sediment samples to determine that Seaside Sparrows were exposed to oil in the environment, this exposure continued for several years, and that storms can play a role in the long-term dynamics of oil exposure in wildlife. Next, using environmental, demographic, and genomic datasets, I determined that habitat and sex were the primary drivers of BAYV prevalence in rice rats, regardless of oiling history (Chapter 3), and that no population genetic bottleneck occurred in rice rats following the spill at our sampling sites (Chapter 4). In the 4th and 5th chapters, I use genomic and transcriptomic data collected from differentially infected rice rats to address questions regarding hantavirus susceptibility and the non-pathogenic tolerance of infection in the reservoir host. I identify three genes with variants related to infection status (Chapter 4) and characterize distinct transcriptomic profiles among differentially infected rice rats (Chapter 5), providing a better mechanistic understanding for how BAYV infections are persistently tolerated in their natural host.
Perez-Umphrey, Anna Alexis, "Long-term Effects of the 2010 Deepwater Horizon Oil Spill on Two Terrestrial Vertebrate Species and the Immunogenetics of a Hantavirus Host" (2021). LSU Doctoral Dissertations. 5654.
Available for download on Monday, August 21, 2028