Date of Award





Earth and Space Science - Environmental Science Track


Earth & Space Science

First Advisor

James A. Gore


One bioassessment tool available to resource managers to indicate NPS impairment of wadeable streams and rivers are multi-metric invertebrate indices. Such indices are assembled from metrics in broad categories that represent different aspects of community structure and function (e.g. richness, composition, tolerance/intolerance, feeding group, and habit). Indices must incorporate suites of metrics that are ecologically relevant, quantifiable, non-redundant, and that best individually discriminate between reference sites and impaired sites. More than 240 wadeable streams in Georgia were sampled during the September thru February index period using RBP protocols during three successive sample seasons (1999-2003). Ecoregional reference (minimally impaired) sites, as well as a gradient of impaired sites, were chosen based on GIS analysis of catchment land use/land cover and riparian and instream physical habitat. Data were analyzed and values calculated for 59 candidate metrics. Individual metrics were evaluated both statistically and graphically for the ability to differentiate between reference and impaired sites. The best metrics were then combined into ecoregional specific discriminating invertebrate indices or reference conditions that classify test streams as biologically comparable to either the reference or impaired group of streams.