Semester of Graduation

Summer 2026

Degree

Master of Science (MS)

Department

Geology & Geophysics

Document Type

Thesis

Abstract

The role of substrate character and vegetation dynamics in the morphological evolution of marsh platforms is not well understood in the Balize Delta of the Mississippi River Delta complex, especially concerning the naturalized species Phragmites australis that is subject to dieback events. To properly calibrate Mississippi River Delta (MRD) evolution models, we need to improve our understanding of the variable and unique sedimentological and ecological feedbacks observed throughout this delicate environment. This understanding is crucial to: (1) limit coastal land loss, (2) restore and protect these highly productive ecosystems and their vital services, and (3) safeguard the region's main industries supporting local communities. This study examines the bulk density, organic content, grain size, and vertical accretion rates at the edges and interior of marsh platforms (~5 m and 15-25 m from the water-land interface of the channel, respectively) hosting Phragmites australis in the Lower Balize “Birdsfoot” Delta. There are substantial differences in the substrate character of the marshes, where the interior sites record significantly greater organic matter (p £ 0.05) and clay content (p £ 0.02) than the edge sites; however, no statistically significant difference was observed in the bulk density, mean grain size, or vertical accretion rates of the edge and interior of platforms (p > 0.05). Most Phragmites australis-dominated marshes in the Balize Delta are keeping pace with documented rates of relative sea level rise, as the 210Pb-VAR produced in this work range from 1.0 to 14.66 cm/yr, and estimates of relative sea level rise in the region range from 1.8-2.5 cm/yr (Fitzpatrick et al., 2021). These data provide insights into the substrate characteristics and eco-geomorphic dynamics of the freshwater, microtidal wetland marshes dominated by Phragmites australis in study sites throughout the Balize Delta.

Date

5-28-2026

Committee Chair

Wilson, Carol

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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Available for download on Thursday, August 31, 2028

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