Date of Award

Summer 8-2022

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Dr. Wei Wu

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dr. Patrick Biber

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Dr. Kevin Dillon

Committee Member 3 School

Ocean Science and Engineering

Abstract

Coastal marshes are one of the most productive and intensively used ecosystems in the world. However, they are under threat due to natural and anthropogenic stressors, such as sea level rise (SLR). SLR can cause marshes to drown, converting them to open water. Marshes can respond to SLR through landward migration when suitable habitat is available. My research focuses on the landward migration pattern and mechanisms. I evaluated the historical land cover changes at the Grand Bay National Estuarine Research Reserve and the Pascagoula River delta over two-time intervals since 1955 and focused on the forest-marsh dynamics. I found that while there were areas of forest transitioning to marsh and the rates of these transitions increased from the first-time interval to the second, gains in marsh area cannot keep up with the amount of marsh lost to forest or water. I then used a mechanistic model to predict soil porewater salinity under different SLR scenarios and found that the maximum salinity band will move up the elevation gradient as sea level increases. This supports landward migration as salinity stress will continue to move up in elevation potentially freeing spaces for marshes to migrate into. Using Bayesian multi-level models, I found that fire management likely helps facilitate landward migration of coastal marshes by increasing productivity of salt marsh and understory vegetation in ecotone and upland forests as well as decreasing tree height growth through increased salinity stress. My findings provide insights as to how marshes respond to SLR and fire management.

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