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Date Permissions Signed

11-14-2016

Date of Award

Fall 2016

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Shull, David

Second Advisor

Yang, Sylvia

Third Advisor

Love, Brooke

Abstract

Sulfide toxicity is implicated in seagrass declines worldwide. Studies examining the relationship between seagrass presence and sulfide concentrations have yielded conflicting results. Interpretation of the seagrass-sulfide relationship is complicated due to the opposing effects of the root system which can increase sulfide oxidation and the burial of organic matter from the plant itself which can increase sulfide production. To quantify the impact of eelgrass leaf detritus and the Zostera marina rhizosphere on pore-water sulfide concentrations, field samples of pore-water sulfide were collected in areas with and without eelgrass. To decouple the effects of live versus dead eelgrass tissue, laboratory studies were conducted over 4 weeks using 10 aquaria with or without eelgrass shoots and 0-8 pieces of Z. marina detritus located at 4 cm and 11 cm depth. Diffusive Gradients in Thin-Films (DGTs) were used to obtain 2D visualizations of sulfide concentrations within the sediment in relation to location of eelgrass detritus and the rhizosphere. In the field study, the presence of leaf detritus accounted for higher than average sulfide concentrations in the sediment. In the laboratory study, the presence of live eelgrass shoots resulted in higher overall sulfide concentrations compared to aquaria without eelgrass. Sulfide concentrations increased with higher mass of added detritus compared to locations where no detritus was added. Sediment within the rhizosphere exhibited reduced sulfide concentrations compared sediment outside the rhizosphere. It is likely that seagrasses are simultaneously increasing and decreasing sulfide concentrations depending on the location analyzed relative to the rhizosphere or buried eelgrass detritus.

Type

Text

Publisher

Western Washington University

OCLC Number

964450267

Digital Format

application/pdf

Genre/Form

Academic theses

Language

English

Language Code

eng

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.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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