Long-term Impacts of Changing Land-use Practices on Water Quality and Phytoplankton Assemblages in the Neuse Estuary Ecosystem, North Carolina

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dc.contributor.advisor Thomas Wentworth, Committee Member en_US
dc.contributor.advisor Cavell Brownie, Committee Member en_US
dc.contributor.advisor JoAnn Burkholder, Committee Chair en_US
dc.contributor.advisor Dave DeMaster, Committee Member en_US
dc.contributor.author Rothenberger, Megan Beth en_US
dc.date.accessioned 2010-04-02T18:55:52Z
dc.date.available 2010-04-02T18:55:52Z
dc.date.issued 2007-11-13 en_US
dc.identifier.other etd-07092007-095443 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/4547
dc.description.abstract The goal of this research was to build upon present understanding of the eutrophication process in the Neuse Estuary ecosystem by evaluating linkages among land use practices, nutrient concentrations and ratios, and phytoplankton assemblage composition. First, geographic Information Systems (GIS) analysis was used to characterize 26 sub-basins throughout the Neuse watershed for changes in land use over the past decade. GIS was also used in concert with multivariate statistics to synthesize and integrate ten years of land cover and water quality data into a conceptual model. Second, a continuous, decadal record of the phytoplankton in the mesohaline Neuse Estuary, in conjunction with synoptic measurement of environmental variables, provided a unique opportunity to evaluate responses of the phytoplankton assemblages to changing environmental conditions. Ordination techniques were used to investigate potential environmental predictors of phytoplankton community patterns through the process of eutrophication. Analyses indicated that over the past 10 years, total phosphorus concentrations were significantly higher during summer months in sub-watersheds with high densities of wastewater treatment plants (WWTPs) and confined swine feed operations. Nitrate concentrations were significantly higher during winter in sub-watersheds with high WWTP densities, and both inorganic and organic forms of nitrogen were significantly higher in sub-watersheds with greater agricultural land use. Ammonium concentrations were significantly higher after high-precipitation periods, but were not significantly correlated with the land-use parameters included in this study. In the Neuse Estuary, among several important findings, abundance of the potentially toxic, bloom-forming dinoflagellate Prorocentrum minimum was positively related to low water temperatures (winter⁄spring) and organic nitrogen and suspended solids concentrations. In addition, abundance of other potentially toxic flagellated algae such as the raphidophyte, Heterosigma akashiwo, has increased over the past decade, and H. akashiwo was found to be an "indicator species" for high ammonium concentrations (> 50 μg⁄L). Overall, the data indicate that wastewater discharges in the upper Neuse basin and intensive swine agriculture in the lower basin have been the highest contributors of nitrogen and phosphorus to receiving surface waters. In the estuary, increased nutrients, especially ammonium, are promoting increased abundance of several potentially toxic, bloom-forming phytoplankton species. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Neuse Estuary en_US
dc.subject longitudinal regression en_US
dc.subject Neuse River Basin en_US
dc.subject ordination en_US
dc.subject phytoplankton en_US
dc.subject land use en_US
dc.title Long-term Impacts of Changing Land-use Practices on Water Quality and Phytoplankton Assemblages in the Neuse Estuary Ecosystem, North Carolina en_US
dc.degree.name PhD en_US
dc.degree.level dissertation en_US
dc.degree.discipline Botany en_US

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