Institute of Ecosystem Studies

2007 BES Annual Meeting Presentation and Poster Abstracts

Relative importance of carbon sources for denitrification in hyporheic zones as a potential indicator of stream restoration success in piedmont streams of the Baltimore LTER
Newcomer, Tamara
Co-Authors: Tamara Newcomer* and Sujay Kaushal, PhD.
Abstract: Though stream restoration represents a multibillion dollar industry in the United States, little is known regarding how ecosystem function in restored streams compares with forested (reference) and urbanized (degraded) conditions. We hypothesized firstly that denitrification potential would vary in forested, degraded, and restored streams with C sources and secondly, that restored streams would exhibit the largest potential because of their high nutrient inputs coupled with increased stream bank connectivity. We examined hyporheic zone denitification potentials associated with various local organic carbon sources in 2 forested, 2 suburban-degraded, and 2 suburban-restored streams in the Baltimore LTER and a suburban stream in Rhode Island. Hyporheic sediment samples were incubated with different carbon treatments (base flow, storm flow, leaves, grass, and algae). Denitrification enzyme activity assays were measured following 3-day incubations with the C sources and KNO3. Denitrification potential in forested streams responded more strongly to C from leaves whereas denitrification potentials in degraded streams responded more strongly to grass. In contrast to what we expected, the denitrification response observed from hyporheic sediments in restored streams more closely resembled that of the forested sites; this suggests microbial communities may adapt to C sources from tree vegetation as opposed to lawns and microbial community functional response changes with stream type. We hypothesize that a streamís denitrification potential could be used as a bioindicator of health and as a metric for stream restoration success.