Date of Award

Spring 2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Frank P. Day, Jr.

Committee Member

Kneeland Nesius

Committee Member

G. Richard Whittecar

Call Number for Print

Special Collections LD4331.B46 S3435 2015

Abstract

Some coastal ecosystems sequester substantially more carbon (blue carbon) than land locked systems due to high net primary production and deposition associated with oceanic influences. Most blue carbon research has focused on mangroves, seagrass beds, and salt marshes. Studies on blue carbon potential of coastal freshwater marshes are less common. Barrier islands frequently flood, with seawater reaching interior ecosystems. I examined brackish/freshwater marshes on Virginia barrier islands for possible roles as blue carbon systems. I studied four interior marshes on Hog Island, which varied in proximity to a direct overwash path and protection by a trail berm that divides northern from southern sites. In order to compare carbon storage rates in these systems to the literature, maximum carbon available for storage at the end of each growing season, or sequestration potential (g C m-2 yr-1), was assessed. Sequestration potential includes production, decay, and deposition, but not other processes that affect carbon storage, like nonbiological oxidation and export. Belowground Net Primary Production (BNPP) was lower for sites directly in the overwash path (40.31g C m-2 yr-1) than for sites not in the path (63.39g C m-2 yr-1). BNPP was greater for sites unprotected by the berm (57.11g C m-2 yr-1) than for protected sites (46.59g C m-2 yr-1). Decay rates for sites not in the overwash path (k = 0.00249 day-1) were greater than for sites in the path (k = 0.00129 day-1). Sediment deposition was greater for sites unprotected by the trail berm than for protected sites. These sites were less productive belowground than salt marshes, and root decay rates were higher than in mid-Atlantic salt marshes, which also had a greater rate of sediment deposition than Hog Island marshes. During this study there were no major overwash events; this lack of overwashes indicates that typical Hog Island sediment deposition rates should be higher than those measured during this study (8.38-26.37 g C m-2 yr-1). The calculated rates of carbon sequestration potential (116.6-233.4 g C m-2 yr-1) indicated that these sites do not store as much carbon as salt marshes (218 ± 24 g C m-2 yr-1), but appear comparable to seagrass beds (138 ± 38 g C m-2 yr-1), and therefore have some blue carbon potential.

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DOI

10.25777/cqfw-hq52

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