Baltimore Ecosystem Study Institute of Ecosystem Studies

2015 BES Annual Meeting Presentation and Poster Abstracts



 
Assessing stream rehabilitation effects on metabolism and nitrogen dynamics of urban streams
 
Reisinger, Alexander
Co-Authors: Thomas R. Doody, Emma J. Rosi-Marshall, Sujay S. Kaushal, and Peter M. Groffman

 
Abstract: Many cities are undertaking hydrogeomorphic stream restoration in an effort to rehabilitate degraded stream ecosystems, but the effect of these restorations on nitrogen (N) dynamics and metabolism of urban streams is unclear. Nitrogen uptake is driven by gross primary production (GPP) and ecosystem respiration (ER) with a stream. Both energy and N dynamics in streams are often assumed to be degraded in urban streams, and urban streams are sources of N pollution to sensitive coastal ecosystems. To improve our understanding of urban stream N and energy dynamics, and the effect geomorphic stream restoration has on streams, we measured N uptake in six Baltimore County and City streams, ranging from an un-restored concrete channel to a stream restored ~20 years ago during Summer 2015. We have also continuously monitored dissolved oxygen in each stream beginning in late Spring 2015, allowing us to model daily GPP and ER. We found that N uptake length ranged from 84-610 m, with the shortest uptake length occurring in a newly restored stream, and the longest uptake length in an un-restored concreted channel. We also found site- specific differences in GPP and ER, allowing us to estimate annual N removal across these six streams. We will continue monitoring stream metabolism and will measure N uptake seasonally in these streams, and an additional six streams in 2016. Ultimately, we will link the ecological outcomes of restorations with socio-economic impacts to find sweet-spots for stream restorations across an urban landscape.