Semester of Graduation

Spring 2019

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Louisiana contains 40% of the nation’s coastal wetlands, but accounts for 80% of the nation’s coastal wetland loss. This loss is attributed to eustatic sea level rise (SLR), regional land subsidence, and sediment starvation. The relative SLR in coastal Louisiana (~13 mm yr-1) puts this area within the predicted level of SLR for most other coastlines in the next 65-85 years; and makes current coastal Louisiana an ideal proxy for studying the future impacts of SLR, wetland loss, and anthropogenic activities on coastal ecosystems worldwide.

There are approximately 1,500 oil spills reported for Louisiana every year and the largest oil spill, the BP Deepwater Horizon oil spill, greatly impacted the Louisiana coastline. In an effort to reduce the damage of oil slicks on the environment, the dispersant Corexit EC9500A was sprayed into the Gulf waters. In Chapter 2, we aim to understand how varying levels of Corexit exposure would initially impact the heterotrophic microbial activity of marsh soil and estuarine sediment in Barataria Basin. Results indicate that there was an increase in the microbial activity of both marsh soil and estuarine sediment at the lower levels of Corexit addition; which has implications for coastal wetland carbon cycling.

The 2017 Coastal Master Plan for Louisiana includes the Mid-Barataria Sediment Diversion which will bring a large influx of nitrate into Barataria Basin when it’s in operation. In Chapter 3, we aim to understand how the ecosystem will react to this diversion in the presence of high rates of wetland loss. An intact core incubation and a potential denitrification experiment were conducted for three bay zones (marsh, submerged peat fringe, and estuary sediment). Results indicate that even though the marsh is eroding, the ecosystem service of water quality improvement (denitrification) is not lost due to the presence of submerged peat soils which continue to support denitrification. The submerged peat and the estuarine sediment may significantly contribute to the nitrate removal from surface waters when the diversion is open. Findings from this study can inform modelers when assessing water quality impacts from river water introduction.

Committee Chair

White, John

Available for download on Tuesday, March 10, 2026

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