Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Division of Plant and Soil Sciences
The demand for natural gas, and the need for efficient extraction, has led to the development of unconventional oil and natural gas (UOG) techniques. Due to the novelty of UOG, the potential impacts to freshwater ecosystems are not fully understood. We used a dual pronged approach to study the effects of UOG development on microbial biodiversity and function via a laboratory microcosm experiment and a survey study of streams with and without UOG development within their watersheds. The laboratory microcosm study simulated stream contamination with produced water, a byproduct of UOG operation, using sediment collected from one high water-quality stream and two low water-quality streams. For the survey study, biofilm and sediment samples were collected from streams experiencing varying levels of UOG development. In the microcosm study, microbial community composition differed significantly between streams, and produced water altered microbial function. Specifically, there was a negative effect on microbial aerobic and anaerobic CO2 production in the high water-quality stream sediment but a positive effect on this microbial activity in the lower water-quality stream sediments, suggesting habitat degradation alters the response of microbes to contaminants. Results from the stream survey study indicated UOG development alters aerobic and anaerobic CO2 production, microbial community composition, as well as stream water temperature and chemistry. Correlations among UOG associated land use, environmental, and microbial variables suggest increases in light availability and sediment delivery to streams, due to deforestation and land disturbance, impact stream microbial communities and their function. Consistent changes in the proportional abundance of bacterial families suggest microorganisms may be good indicators of the environmental changes associated with UOG development. The observed impacts of UOG development on microbial community composition and carbon cycling could have cascading effects on stream health and broader ecosystem function.
Michaels, Rachel, "Microbial responses to unconventional oil and gas development may alter ecosystem function in headwater streams" (2020). Graduate Theses, Dissertations, and Problem Reports. 7900.