Assessment of aquatic invertebrate communities of tributaries of the Buffalo River, Arkansas, and evaluation of indices of community integrity

The U.S. National Park Service developed an Index of Community Integrity (BRICI) for the Buffalo National River, Arkansas aquatic invertebrate community based on 10 individual metrics.  The BRICI has been successfully evaluated on mainstem segments of the river, but not on tributaries in the watershed.  The purpose of this study was to evaluate the BRICI on tributaries in the Buffalo River watershed, compare them to the Missouri Stream Community Index (SCI) that uses only four individual metrics, and determine which metric serves as the better predictor of community integrity in the watershed.  The BRICI and SCI were calculated from data collected from 29 tributaries located throughout the watershed during late-fall through winter, 1993 through 2007, using comparable semi-quantitative methods.  The BRICI was found to better represent the overall health of the invertebrate community in comparison with the more conservative SCI.  Results showed a downward trend of decreasing community integrity along the river from upper to lower reaches for both indices.  Based on significant correlations (α < 0.05), the BRICI appears to be more responsive to local and regional environmental factors of the complex Buffalo River watershed including land use, geology, riparian cover, substrate composition, vegetation, specific conductance, and nitrogen levels.