Evaluating Biotic Functional Lift Provided by Physical Habitat Rehabilitation in Urban Streams of the Ridge and Valley Physiographic Province of Tennessee

The business of stream restoration is a billion dollar industry today. Funds are used to correct anthropogenic damage to hydrologic and geomorphic functionality and to allow natural processes to return. Unfortunately, ecological improvement from stream restoration projects, particularly in urban watersheds, have had mixed results. Several reasons exist for limited improvements include: 1) inadequate ecological design criteria based on re-colonization potential and habitat requirements as determined by functional traits expression of 2) insufficient pre- and post-monitoring methods, 3) the biological assemblage chosen for the bioassessment is not sensitive to the restoration actions, and 4) lack of a watershed-scale stressor analysis and adequate project scoping and prioritization. The purpose of this study was to: 1) determine if stream habitat restoration has had an effect on the biotic integrity of fish and benthic macroinvertebrate assemblages in urban streams within the Ridge and Valley Physiographic Province of east Tennessee, and 2) evaluate the effect of stream restoration on the biotic lift in functional traits expressed by fish and benthic macroinvertebrate assemblages. Twelve sites were selected, whereby three were considered physically restored for at least seven years, three were impaired reaches from varied levels of urbanization, and three streams were considered ecoregion reference streams to serve as a baseline for healthy benthic integrity. Invertebrates were collected bimonthly along with water quality and habitat quality data, and fishes were sampled semi-annually. To assess ecosystem health, index of biotic integrity (IBI) metrics and scores were calculated for each sample for fish and benthic macroinvertebrates, respectively, following Tennessee Valley Authority (TVA) and Tennessee Department of Environment and Conservation (TDEC) protocols. Results indicated that restored stream reaches showed improvement over impaired stream reaches, but did not score as high as ecoregion reference streams. Restored streams were observed with higher IBI scores on average than impaired streams for both fish and insect IBI metrics, in addition to improved habitat quality index scores. More research is still needed to properly understand urban stream ecosystems and the effects of stream restoration on the aquatic world.