Date of Award

Winter 2025

Project Type

Thesis

Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

David Burdick

Second Advisor

Richard Smith

Third Advisor

Christopher Peter

Abstract

Salt marshes are critical coastal wetlands that provide valuable ecosystem services including coastal erosion control, carbon sequestration, water quality improvement, fisheries habitats, and recreational and economic opportunities for coastal communities. To better understand salt marshes and the changes occurring within the systems due to environmental and human factors, monitoring of established sites is conducted to look at variables such as vegetation cover, elevation, fauna, and vertical accretion. Methodological differences amongst monitoring efforts can result in data that has differing implications when analyzed and interpreted, so documentation of protocols (and any deviance from them) is imperative when bringing together datasets. The National Marsh Synthesis Team project utilized salt marsh monitoring data sets collected at sentinel sites across twenty-two (22) of the National Estuarine Research Reserves (NERRs) to investigate the changes in vegetation in response to sea-level rise. Through the data cataloging and reconciliation process, differences in data collection methods for a variety of variables were identified, dictating what data could be synthesized across all the participating Reserves. The takeaways from the NaMaSTe project provided valuable insight that can be applied to existing salt marsh monitoring data sets and informed the protocol priorities that should be considered when establishing protocols for future monitoring efforts.Using monitoring protocols adapted from those used by the NERRs, the impacts of historic agricultural embankments on salt marsh vegetation and hydrology was investigated at four NERRs in New England including: Wells (Maine), Great Bay (New Hampshire), Waquoit Bay (Massachusetts), and Narragansett Bay (Rhode Island). The hydrology data collected from this study did not show the embanked areas to have prolonged hydroperiods and reduced tidal exchange. Vegetation data from all the sites showed a significant difference in cover between the embanked marsh areas and the reference marshes for five of the seven cover categories. Results from Wells (p=0.0012) and Narragansett Bay (p=0.002) showed that the presence of embankments had a substantial impact on the vegetation composition (as determined by multivariate community analysis), while at Great Bay and Waquoit Bay, significant differences were only observed with univariate analyses of specific cover categories.

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