CAREER: Potential for the Recovery of Biogeochemical Function in Degraded Stream Ecosystems

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A growing body of research demonstrates the important effect undisturbed stream ecosystems have in altering the form, timing and magnitude of watershed nitrogen (N) losses. It is less clear whether, and to what extent, this capacity is reduced during watershed degradation. Emily Bernhardt is examining whether and how critical biogeochemical functions (the removal of reactive nitrogen and community metabolism) are affected in urban streams, and whether these streams have the capacity to recover those functions through 1) longitudinal transport through unmodified landscapes (natural recovery) or 2) extensive channel reconfiguration restoration efforts (manmade solutions). Bernhardt will experimentally test whether removal rates of nitrogen are strongly carbon limited in urban streams. This is likely because the organic matter necessary to fuel microbial activity is lost in frequent stormflow events typical of urban watersheds.Ultimately this research will increase our mechanistic understanding of stream nitrogen cycling, and will provide much needed information for guiding water resources management. The field sites used and the data generated from them will be used for introducing state managers, regional restoration practitioners, and environmental professional school students to aquatic ecosystem research. Bernhardt will also use this research as a platform for classes in aquatic ecology at a NC science magnet highschool and for Duke undergraduate students.