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Date Permissions Signed

3-27-2008

Date of Award

2008

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Rybczyk, John M.

Second Advisor

Shull, David, 1965-

Third Advisor

Wallin, David O.

Abstract

The dynamics that govern the elevation of a coastal wetland relative to sea level are complex, involving non-linear feedbacks among opposing processes. Changes in the balance between these processes can result in significant alterations to vegetation communities that are adapted to a specific range of water levels. Given that the accretion rate in Padilla Bay, Washington, is suspected to be considerably lower than historical levels and that eustatic sea level rise continues to accelerate, the long term sustainability of the Zostera marina (eelgrass) meadows in the bay may be at risk to eventual submergence. I extended an existing Relative Elevation Model that incorporates many of the non-linear feedbacks that govern estuarine sediment dynamics by adding a spatial component. I used the model to project changes in Padilla Bay bathymetry and Z. marina distribution and productivity over the next century given various sea level rise scenarios. Analysis of field data collected in Padilla Bay for calibration and validation of the model indicated a net accretion deficit of 0.463 ± 0.173 cm/yr. Model projections for 100 years showed an increase in depths within the bay over time under all scenarios. Total annual Z. marina productivity and spatial coverage was greater at the end of the simulations than at the initial state for most scenarios due to shoreward expansion. In the most extreme scenarios, it reached a peak between 2052 and 2077 and began to decline as it was pushed beyond the existing shoreline. These results suggest that Padilla Bay is not stable with respect to rising sea level. It is possible that the increase in Z. marina productivity may be beneficial to marine organisms in the near term, but the projections indicate that this is only a temporary state until a peak and subsequent decline in total Z. marina productivity is reached.

Type

Text

Publisher

Western Washington University

OCLC Number

233830947

Digital Format

application/pdf

Geographic Coverage

Padilla Bay (Wash.)

Genre/Form

Academic theses

Language

English

Rights

Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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