HR: 15:30h
AN: NB24B-01    [Abstracts]
TI: Nitrogen Retention in Three Streams in the Piedmont Region of North Carolina Using a ¹⁵N Tracer Addition
AU: * Rushforth, H M
EM: hmrushfo@uncg.edu
AF: Department of Biology, University of North Carolina-Greensboro, Greensboro, NC 27402 United States
AU: Hershey, A E
EM: aehershe@uncg.edu
AF: Department of Biology, University of North Carolina-Greensboro, Greensboro, NC 27402 United States
AB: Stream restoration is often done as a compensatory mitigation project, but it is unresolved as to what extent restoration helps restore natural nutrient cycling within streams. During the summer of 2004 we ran a stable isotope drip of ¹⁵ NH ₄Cl for 4 weeks in a forested pristine stream, an unrestored urban stream (but with a restored riparian zone), and a restored urban stream (restored channel and riparian zone). All three streams were located in the piedmont region of North Carolina. By collecting and analyzing samples along a 500m reach in each stream we were able to trace ¹⁵N uptake into the food web components. Preliminary results indicate that the restored stream was less retentive of ¹⁵N in periphyton and other food web components than the unrestored stream. Differences between these two urban streams likely reflect continued nitrogen loading rather than the instream conditions. The unrestored urban stream had consistently higher mean algal biomass than the other two streams. Grazers were consistently more enriched than periphyton in all streams. Hydropsychid caddisflies were isotopically similar to grazers in the forested and unrestored stream, but tracked seston in the restored stream indicating considerable variability in their trophic status.
DE: 1803 Anthropogenic effects
DE: 1860 Runoff and streamflow
DE: 4845 Nutrients and nutrient cycling
DE: 4870 Stable isotopes
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly