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Author ORCID Identifier

https://orcid.org/0000-0002-8337-9428

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Geosciences

Year Degree Awarded

2023

Month Degree Awarded

February

First Advisor

Jonathan D. Woodruff

Second Advisor

Brian C. Yellen

Third Advisor

Timothy L. Cook

Fourth Advisor

Don J. DeGroot

Subject Categories

Climate | Earth Sciences | Environmental Indicators and Impact Assessment | Environmental Sciences | Forest Biology | Geology | Geomorphology | Marine Biology | Other Oceanography and Atmospheric Sciences and Meteorology | Sedimentology | Soil Science | Stratigraphy

Abstract

Tidal wetlands are vital for buffering coastal settings from the threats of accelerated sea level rise and storms. Understanding the factors that are most influential for the maintenance and recovery of tidal wetlands after extreme events compounded by future accelerated sea level rise is of the utmost importance, yet this knowledge is not well established. Two tidal wetland schemas investigated in this dissertation are mangrove systems in Vieques, Puerto Rico (including robust lagoonal-mangrove forest systems and fringing mangrove forests), and salt marshes in New England. While the climatic forcings, vegetation type, and locations are vastly different for these two tidal wetlands, there is considerable overlap in the stressors and factors needed for resilience. Chapter 1 provides background information on tidal wetlands, and the stressors impacting them.

Chapters 2 and 3 examine hurricane impacts and recovery for mangrove forests in Puerto Rico. The recovery potential of mangroves influences the long-term buffering capacity of these unique coastal forest systems in terms of wave attenuation, wind breaking, and sediment overwash deposition. Different mangroves, however, respond differently to hurricanes based on the direction and intensity of impact during the storm, and the indirect impacts that occur after the storm has passed. Fringing mangroves on exposed coasts, such as those examined in chapter 2 at Laguna Playa Grande on the south side of Vieques, are more impacted by direct damages. In more protected regions that have a more robust forest with a variety of mangrove species, impacts are more indirect as a result of a delayed mortality from damage occurred during the event and reduced resilience to environmental stressors following the event. In addition to the damages from hurricanes, human disturbance to mangrove forests plays a major role in the system’s ability to recover, leaving coastlines more vulnerable to damages and storm-induced deposition during the recovery phase following the event.

Chapter 4 presents a method for assessing the sourcing, timing, and mechanism of clastic sediment to New England marshes using a new cost-effective sediment trap design. In addition to the sediment trap methodology, we also present a regional assessment for the sourcing and timing of delivery for representative salt marsh in the region through analysis of instrumental data from turbidity sensors and water level loggers, as well as accumulation of clastic sediments on the marsh surface through sediment traps to assess the seasonal delivery of inorganic sediment to salt marshes. Three representative marshes were chosen to cover the wide variety of salt marsh systems in the region from the microtidal marshes south of Cape Cod, MA (Westport) to the mesotidal marshes in Maine (Sprague and Wells). Due to oceanographic, geologic, and environmental differences in marsh systems throughout the region, a heterogeneity in sourcing and timing of sediment supply is observed. This study provides valuable regional context for the spatial and temporal differences of inorganic sediment sourcing and delivery to New England salt marshes.

DOI

https://doi.org/10.7275/33207234

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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