Doctor of Philosophy (PhD)
On April 20, 2010, the Deepwater Horizon oil spill released an estimated 779 million liters of Macondo-252 crude oil into the Gulf of Mexico, making it the largest marine oil spill in history. Over a thousand kilometers of marshland that many species of fish use as a spawning grounds and nurseries was oiled, exposing breeding adult fish and their offspring to oil. My dissertation investigates the impacts of the Deepwater Horizon oil spill and associated remediation efforts on the reproduction and ontogeny of a sentinel ecotoxicological species, the Gulf killifish (Fundulus grandis). Concerns were raised regarding use of freshwater diversion release and application of chemical dispersants for coastal remediation efforts as the effects of their concurrent use on coastal ecosystems had not been investigated. My research found that chemical dispersants become toxic to Gulf killifish during normally benign acute osmotic challenges through disruption of osmoregulatory physiology. Toxicity increases throughout ontogeny, concomitant with development of the gill as an osmoregulatory organ. Next, a novel high throughput methodology was developed to investigate the interaction of crude oil droplets with Gulf killifish embryos and found that binding characteristics of oil droplets to chorions differ based on if they were physically or chemically dispersed, and on chorionic morphology. Assessing binding characteristics of oil droplets to chorions is important in understanding the toxicity of crude oil as toxic components may be transmitted to embryos through direct adsorption of droplets. Lastly, intergenerational effects of oil exposure were investigated through exposure of adult Gulf killifish and their offspring to oil. Oil exposure reduced the reproductive capacity of adult fish and sensitized offspring to additional oil toxicity during embryogenesis. Population level differences were also observed as a population of killifish collected three years following Deepwater Horizon oiling of their habitat possessed increased oil sensitivity compared to a reference population, suggesting that oil spills continue to impact fish well beyond initial oiling. Overall, these results provide a comprehensive characterization of the damage imposed by the Deepwater Horizon oil spill and provides insight into mechanisms of toxicity that should be considered for future spills.
Brown, Charles Alexander, "Impacts of the Deepwater Horizon Oil Spill on Reproduction and Ontogeny of Gulf Killifish (Fundulus grandis)" (2020). LSU Doctoral Dissertations. 5141.