Haustein, Mitchell Donald2011-04-282011-04-282010-11https://hdl.handle.net/11299/103264University of Minnesota M.S. thesis. December 2010. Major: Ecology, Evolution, and Behavior. Advisor: Dr. Robert W. Sterner. 1 computer file (PDF); viii, 68 pages.The rate of urbanization of land has increased dramatically over the past decades and is expected to continue increasing as global populations continue to rise. Modifications of land associated with urbanization undoubtedly affect the adjacent and surrounding ecosystems, and urban ecosystem science has become an increasingly popular area of research to assess and quantify the ramifications of such drastic changes. The prevalence of impervious surfaces, one of the most defining characteristics of urban areas, has fundamentally altered the hydrology of urban ecosystems through decreased infiltration of surface water and rerouted hydrological flow paths. As a result, aquatic ecosystems positioned within urbanized areas have been significantly influenced by increases in stormwater runoff associated with efficient drainage networks. The altered hydrology within these urban systems has been shown to consistently negatively impact overall stream health. In contrast, urban lakes have been much less studied, yet have clearly been impacted by urbanization. Shallow lakes within the Twin Cities Metropolitan Area, Minnesota were assessed in 2007 for phytoplankton nutrient limitation and in 2007-2009 for nutrient biogeochemistry. Phytoplankton exhibited either multiple or co-nutrient limitation by nitrogen, phosphorus, and silica in 12 of the 17 lakes sampled in 2007. Strong negative relationships were observed across a gradient of impervious surface percentage within surrounding lake buffers for both TDN and DOC in 2007 and 2008. However, this gradient of imperviousness ranged from an agriculturally dominated landscape to a highly urbanized landscape. Therefore, lakes assessed in 2009 included reference sites dominated by forested land cover; these displayed similar concentrations iii of TDN and DOC as urban lakes. Chemical characterization of the DOC across these lakes nevertheless suggests DOC within urban lakes is dominated by autochthonous sources, while DOC in forested and agricultural lakes is dominated by allochthonous sources. These results suggest that urbanization, characterized by impervious surface land cover, and agricultural land use affect nutrient biogeochemistry and DOC character within lakes.en-USUrbanization of landGlobal populationsUrban ecosystemUrban lakesEcology, Evolution, and BehaviorUrbanized landscapeThesis or Dissertation