Degree

Doctor of Philosophy (PhD)

Department

Oceanography and Coastal Sciences

Document Type

Dissertation

Abstract

Coastal wetland ecosystems are inherently interdisciplinary; in these spaces, the physical forces of wind and water meet to interact with stabilizing and fortifying vegetation and biota, as well as mud. The combination of these factors build and sustain wetland ecosystems and without the complex feedbacks, they would cease to exist. In this dissertation, I present three studies that focus on ecogeomorphic interactions within coastal wetlands on a range of scales, from microscopic to the entire landscape and highlight the importance of these interactions when predicting future coastal change. The first study examined how biofilms, matrixes of photosynthetic diatoms and their sticky secretions, stabilize sediments under increased nutrient loads. Using laboratory experiments, I found that biostabilization occurs under any nutrient conditions, and that eutrophication could cause faster rates of stabilization. Secondly, I conducted a field and modeling study that explored how water level and plant roots interact to affect marsh edge erosion variability. Depending on the water level, waves can impact the root zone where marsh soils are stronger or they can impact below the roots where the soil is more erodible. This leads to spatially-variable erosion rates, where north-facing shores erode twice as fast as south-facing shores. Lastly, I develop a model motivated by field measurements of soil strength to incorporate the role of landscape-scale salinity zonations in marsh erodibility. In this study I show that different salinity zones within an estuary result in different soil and vegetation properties, necessitating an adjustment to marsh edge retreat models to adequately represent erosion on a basin scale. Understanding these biogeomorphic interactions is critical, not only for improving the scientific knowledge on marsh processes, but also for coastal restoration and protection projects.

Date

2-28-2020

Committee Chair

Mariotti, Giulio

Available for download on Thursday, February 25, 2021

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