A Spatial and Multivariate Approach to Examining Effects of Urbanization on Nitrogen Sources, Organic Matter Inputs, and Trophic Structure in Streams of Cobb and Paulding Counties, Georgia.
Date of Award
Master of Science in Integrative Biology (MSIB)
First Committee Member
Second Committee Member
Urbanization and land use changes have a negative effect on streams often causing numerous physical changes in stream morphology, a change in nutrient concentrations, and altered ecosystems contributing to a loss of habitat, decreased biodiversity, and loss of stability for ecosystem function (Walsh et al., 2005; Meyer et al., 2005; Cardinale and Palmer, 2012). The use of stable isotope analysis for monitoring could be valuable because it accounts for temporal integration from anthropogenic wastewater inputs, characterized by a shift in the abundance of 15N. This project had three main objectives: (1) to examine how nitrogen and carbon sources are altered with the use of spatial trends of δ15N values in streams with varying levels of urbanization; (2) to examine how the effects of urbanization, altered nitrogen and organic matter inputs play a role in trophic structure within aquatic ecosystems by examining isotopic food webs; and (3) to see if these variables could be utilized for spatial predictability of urban impacts on streams. We found support for the notion that high levels of developed land use and agricultural land use correspond with an increase in the ẟ15N values of macroinvertebrates. Our food webs and ẟ15N values suggested that certain organisms changed their role in the food web consistent with a shift in the food web towards omnivory. Use of impervious surface area, land cover land use and ẟ15N to monitor water quality could provide an early indicator for stream degradation.
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