Collaborative Research: A Stoichiometric Approach to Coupled N and P Cycling in Headwater Streams

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Nutrient cycling along the length of streams is often studied to understand the net uptake of nitrogen (N) or phosphorus (P) in these waters. Most studies have addressed the cycling of N or P independently. In this study, investigators will develop techniques to address the coupled cycling of N and P in streams. Standard protocols for such experiments involve experimental elevation of nutrient abundance, creating an unwanted 'fertilization effect'. In this research project, the investigators will use stable isotopes to ensure measures of gross (i.e., non-fertilized) elemental uptake and show how coupled uptake is tied to the elemental composition of stream algal and bacterial layers. This is a pilot study to test the feasibility of this approach. Streams may be important sites of N uptake on the landscape in the face of increased N deposition from human activities. Biological processes affecting N retention are simultaneously influenced by the cycling of other elements. This work will contribute to understanding how natural processes provide self-purification in streams and how N and P interact as potentially limiting nutrients to dictate water quality. The work will involve training post-doctoral, graduate, and undergraduate participants and public outreach.