Comparison of Community Metabolism in two Streams With Different Landuse

Gross primary production (GPP) and community respiration (CR) were measured in a forested (Panther Creek) and an agricultural stream (Ledbetter Creek) using the single-station, open-system method. Reaeration coefficients were estimated using the energy-dissipation model. Both GPP and CR were consistently higher in the forested stream than the agricultural stream. P/R ratio ranged from 0.09 to 0.23 showing the heterotrophic nature in both streams. In Panther Creek, mean daily GPP (1.58 gO2/m2) and CR (15.82 gO2/m2) were significantly higher during fall than summer (GPP=1.17 gO2, CR=5.02 gO2/m2). However, the seasonal differences in daily GPP (0.45 gO2 in summer and 0.33 gO2/m2 in fall) and CR (2.39 gO2 in summer and 3.53 gO2/m2 in fall) were not significant in Ledbetter Creek. Higher GPP and CR in the forested stream can be attributed to more stable hydrology and sediment composition compare to the agricultural stream that is subject to frequent spates and sediment movements. The higher metabolic activities observed in Panther Creek during fall compare to summer is a result of combined effect of higher light intensity reaching to benthic community and increased organic matter post litterfall.