Interregional comparisons of sediment microbial respiration in streams

1. The rate of microbial respiration on fine-grained stream sediments was m easured at 371 first to fourth-order streams in the Central Appalachian reg ion (Maryland, Pennsylvania, Virginia, and West Virginia), Southern Rocky M ountains (Colorado), and California's Central Valley in 1994 and 1995. 2. Study streams were randomly selected from the United States Environmenta l Protection Agency's (USEPA) River Reach File (RF3) using the sample desig n developed by USEPA's Environmental Monitoring and Assessment Program (EMA P). 3. Respiration rate ranged from 0 to 0.621 g O-2 g(-1) AFDM h(-1) in Centra l Appalachian streams, 0-0.254 g O-2 g(-1) AFDM h(-1) in Rocky Mountain str eams, and 0-0.436 g O-2 g(-1) AFDM h(-1) in Central Valley streams. 4. Respiration was significantly lower in Southern Rocky Mountain streams a nd in cold water streams (< 15 degrees C) of the Central Appalachians. 5. Within a defined index period, respiration was not significantly differe nt between years, and was significantly correlated with stream temperature and chemistry (DOC, total N, total P, K, Cl, and alkalinity). 6. The uniformity of respiration estimates among the three study regions su ggests that sediment microbial respiration may be collected at any number o f scales above the site-level for reliable prediction of respiration patter ns at larger spatial scales.