Date of Award


Document Type

Open Access Thesis


Marine Science


College of Arts and Sciences

First Advisor

Lori Ziolkowski


Oil from the Deepwater Horizon (DwH) spill continues to be found on beaches five years post-spill. Understanding the role of microbes in removing DwH oil from sandy beaches is necessary to elucidate the fate of DwH oil in the coastal zone. Oiled sand patties and non-oiled sand were collected from affected beaches five years post- DwH. Biomarkers in oiled sand indicated that sand patties originated from the DwH spill, however the oil was heavily weathered and dominated by oxygenated hydrocarbons. Microbial communities, as measured by phospholipid fatty acids (PLFA), were present on oiled sand patties and distinct from microbes on non-oiled sand. Stable-carbon and radiocarbon measurements of PLFA show microbes on oiled sand patties were using different carbon sources than microbes on non-oiled sand. Radiocarbon measurements of bulk organic carbon and PLFA demonstrated that microbes on oiled sand patties were assimilating highly weathered DwH oil five years post-spill. These results are the first to show in situ biodegradation of highly weathered oil and have implications for removal of DwH oil continuing to wash ashore.