The impact of nutrient loading on nitrogen removal and carbon dynamics in a juncus roemerianus and spartina alterniflora dominated salt marsh in the northern Gulf of Mexico

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dc.contributor Cherry, Julia A.
dc.contributor Mason, Olivia
dc.contributor.advisor Mortazavi, Behzad
dc.contributor.author Ledford, Taylor
dc.date.accessioned 2020-01-16T15:03:29Z
dc.date.available 2020-01-16T15:03:29Z
dc.date.issued 2019
dc.identifier.other u0015_0000001_0003371
dc.identifier.other Ledford_alatus_0004M_13920
dc.identifier.uri http://ir.ua.edu/handle/123456789/6428
dc.description Electronic Thesis or Dissertation
dc.description.abstract Increased anthropogenic nutrient loading of nitrogen (N) and phosphorus (P) to estuaries and bays can lead to eutrophication, anoxia or hypoxia, and/or loss of native or other important species. Coastal salt marshes help to counteract eutrophication by removing excess N through microbially-mediated denitrification. One important factor that regulates salt marsh N removal is vegetation type, which affects sediment N-removal capacity by modifying redox potential and altering the microbial community structure within sediments. Additionally, plant community structure can alter carbon (C) uptake via photosynthesis and C release via sediment oxidation and organic matter degradation. A 1-year field study was conducted in a salt marsh located on Dauphin Island, AL, where we increased N and P inputs by 20 g N m-2 yr-1/ 1.25 g P m-2 yr-1 (low fertilization) and 40 g N m-2 yr-1/2.5 g P m-2 yr-1 (high fertilization) in plots dominated by either Juncus roemerianus (black needlerush) or Spartina alterniflora (smooth cordgrass). Denitrification was 5X higher in unamended J. roemerianus plots versus S. alterniflora, but denitrification in S. alterniflora was more responsive to fertilization, increasing ten-fold while denitrification in J. roemerianus plots did not respond to fertilization. Gross primary productivity (GPP) was marginally higher (~5%) in control plots of J. roemerianus than in control S. alterniflora plots. High fertilization increased GPP by 27% in S. alterniflora plots, however, GPP did not respond to fertilization in J. roemerianus plots. Additionally, ERCO2 was similar across vegetation types in control plots, and did not respond to fertilization in either vegetation type. Net ecosystem exchange was similar in J. roemerianus and S. alterniflora control plots and did not change in response to N and P additions for either vegetation type. Our results illustrate that while both J. roemerianus and S. alterniflora marshes have the capacity to withstand nutrient loading in the Gulf of Mexico via N removal, S. alterniflora dominated marshes may have a greater capacity to mitigate N inputs. Additionally, in a world with higher nutrient inputs and despite higher GPP in S. alterniflora, both vegetation types will continue to sequester C at similar rates.
dc.format.extent 49 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Biogeochemistry
dc.title The impact of nutrient loading on nitrogen removal and carbon dynamics in a juncus roemerianus and spartina alterniflora dominated salt marsh in the northern Gulf of Mexico
dc.type thesis
dc.type text
etdms.degree.department University of Alabama. Department of Biological Sciences
etdms.degree.discipline Biological Sciences
etdms.degree.grantor The University of Alabama
etdms.degree.level master's
etdms.degree.name M.M.S.


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