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Author ORCID Identifier

https://orcid.org/0000-0001-9864-424X

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Plant, Soil & Insect Sciences

Year Degree Awarded

2019

Month Degree Awarded

September

First Advisor

Baoshan Xing

Second Advisor

Michelle DaCosta

Third Advisor

Kevin McGarigal

Subject Categories

Life Sciences | Marine Biology

Abstract

A scientific basis for understanding the health of salt marsh vegetation, primarily Spartina alterniflora, in apposition to dredging of the tidal inlet to Ellisville Marsh in Plymouth, Massachusetts was determined. A three-hectare S. alterniflora loss, and coincident coastal bank erosion occurred; ostensibly due to inlet blockage from sand deposition, prolonged inundation, and meandering of inlet channel into coastal bank. This warranted dredging the tidal inlet, whereby tidal flushing would restore growth or discontinue die-off, and deter coastal bank erosion. A pre- and post dredge study was conducted assessing environmental factors related to plant productivity. Following dredging, an increase in tidal range (0.2 m, pS. alterniflora increased from pre-dredge conditions in both landscape and plot level assessments (pS. alterniflora and Spartina patens coverage decreased (pS. alterniflora stem density, above and below ground biomass decreased (pS. alterniflora height increased linearly with hydroperiod (p2= 0.12). Root alcohol dehydrogenase activity and redox were inversely correlated, and mean redox shifted from -100 mv to +100 mv (pHaliaspis spartinae, an insect pest, was found to be associated with hydroperiod. The Marsh Equilibrium Model (MEM v. 5.4) demonstrated vertical resilience, whereas the Unvegetated to Vegetated Index (UVVI) approach did not show horizontal resilience. Hydroperiod substitution for depth in the MEM yielded lower biomass estimates and less vertical resilience. A significant (p

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