An evaluation of the sensitivity of a macroinvertebrate biomonitoring study in headwater streams of New River Gorge National River

I examined the sensitivity of 16 biological metric scores derived from bent hic macroinvertebrate assemblages of small streams in New River Gorge Natio nal River. A stream presumed to have its macroinvertebrate assemblage struc ture impaired by an abandoned landfill (Rush Run) was used to represent the "impacted" condition. It's fauna were collected from two longitudinally di stinct loci and compared to two sets of reference streams because upper and lower elevation streams exhibited marked difference in benthic community s tructure. Thus, a site on upper Rush Run was contrasted to five other "uppe r" reference streams and a site on lower Rush Run was compared to five "low er" reference streams with a one sample t-test. Most of the selected metric s highlighted the impairment of lower rush run, relative to lower streams. Whereas only Ephemeroptera-Plecoptera-Trichoptera richness and three varian ts of the biotic index described impairment of upper Rush Run. Subsequent p ower analysis indicated that both upper and lower reference streams had sim ilar statistical sensitivity, but that environmental sensitivity was greatl y reduced at upper elevations streams. This was probably due to harsher env ironment of upper streams (intermittent flow, reduced buffering capacity).