Wednesday, June 6, 2007 - 8:15 AM
184

Spatial Variation of Benthic Bioassessment Metric Scores in Virginia Piedmont Streams

Andrew L. Garey and Leonard L. Smock. Department of Biology, Virginia Commonwealth University, 1000 West Cary Street, Richmond, VA 23284-2012

Variation among benthic communities depends on the intensities and spatial scales of natural phenomena and anthropogenic disturbances within streams and their surrounding watersheds.  We conducted a study to determine the spatial variability of benthic macroinvertebrate bioassessment metrics within six 2nd- and 3rd-order study catchments in the Piedmont Physiographic Region of Virginia and to determine if relationships existed between metric variability and various environmental parameters.  We sampled benthic macroinvertebrates, conducted physical habitat assessments, and measured physicochemical water quality parameters at 7-16 sites within each catchment.  Land- cover within catchments was assessed using GIS data sets.  The metrics and scoring system used were those included in the Virginia Stream Condition Index for Non-wadeable Streams.  Urbanized catchments, with the most degraded benthic communities, exhibited lower metric variability than catchments dominated by agriculture and forests.  The effects of physical habitat quality and land-cover at the riparian scale were constrained by and secondary in importance to large-scale catchment land-cover.  Metrics were spatially autocorrelated in most study catchments.  The strength of this correlation depended on how between-site distances were measured.  The results of this study suggest that the precision of data collected as part of bioassessment programs varies depending on the extent of stream degradation. 

See more of Bioassessment II
See more of Contributed Sessions

See more of The NABS 55th Annual Meeting