Seagrass Carbon Standing Stock in the Northern Gulf of Mexico: The Role of Seagrass Beds in Mississippi as Potential Blue Carbon Sinks

Author

Devan HildebrandFollow

Date of Award

12-2025

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Dr. Zachary Darnell

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dr. Kelly Darnell

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Dr. Melissa M. Baustian

Abstract

Organic carbon stored in marine ecosystems is known as blue carbon. Seagrass beds have the ability to contribute to global blue carbon standing stocks through the uptake and sequestration of carbon from the water column. Through coastal management and conservation best practices, blue carbon habitats have the potential to help mitigate the effects of climate change. Although widely studied, knowledge gaps exist on the sediment carbon standing stock of seagrasses. I aim to better understand how persistent seagrass meadows surrounding barrier islands in the northcentral Gulf of Mexico contribute to long-term blue carbon standing stocks. Subaqueous sediment cores were collected to 1-m depth in seagrass meadows and bare sediment habitats surrounding Cat Island, Mississippi to characterize the carbon storage capacity of these habitats. Sediment cores were analyzed for grain size, bulk density, total organic carbon, organic matter, and total seagrass biomass. While both seagrass and bare sediment habitats contained stored carbon, the sediment cores associated with seagrass had a significantly higher sediment percent C_org content (mean 0.214 ± 0.031%) than cores collected from bare sediment habitats (mean 0.102 ± 0.007%). The sediment C_org standing stocks at 30 cm (seagrass 7.22 Mg C_org ha^-1; bare sediment 4.35 Mg C_org ha^-1) depths and 100 cm (seagrass 42.6 Mg C_org ha^-1 ; bare sediment 21.0 Mg C_org ha^-1) depths for seagrass and bare sediment were not significantly different and tended to be an order of magnitude less than global values. These findings align with prior studies and support the idea that seagrass beds can create and maintain substantial blue carbon standing stocks. This is the first known quantification of sediment carbon sequestration potential of subtidal habitats surrounding the Mississippi barrier islands.

Copyright

Devan N. Hildebrand, 2025

Recommended Citation

Hildebrand, Devan, "Seagrass Carbon Standing Stock in the Northern Gulf of Mexico: The Role of Seagrass Beds in Mississippi as Potential Blue Carbon Sinks" (2025). Master's Theses. 1161.
https://aquila.usm.edu/masters_theses/1161