HR: 1340h
AN: B43C-0291    [Abstracts]
TI: Validation and Regional Application of Three Biologically Based Urbanization Models in the South Atlantic Gulf and Tennessee River Basins
AU: * Cuffney, T F
EM: tcuffney@usgs.gov
AF: U.S. Geological Survey, 3916 Sunset Ridge Road, Raleigh, NC 27607 United States
AU: Giddings, E M
EM: giddings@usgs.gov
AF: U.S. Geological Survey, 3916 Sunset Ridge Road, Raleigh, NC 27607 United States
AU: Gregory, M B
EM: bgregory@usgs.gov
AF: U.S. Geological Survey, Peachtree Business Center, Suite 130 3039 Amwiler, Atlanta, GA 30360 United States
AB: Investigations are underway as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program to determine the effects of urbanization on streams across the United States. These studies will help to determine how biological, chemical, and physical characteristics of streams change along gradients of urban intensity defined by a multimetric urban-intensity index (UII). Biological-response models were derived by using ordination analysis to determine the ecological distances among sites along the dominant environmental gradient, as defined by the benthic macroinvertebrate assemblages, and then relating these distances (ordination site scores) to the UII using linear regression. Response models were derived for three urban areas in the Southeast: Birmingham, AL (BIR); Atlanta, GA (ATL); and the urban corridor along I-40 in NC (RAL: Raleigh Greensboro Winston-Salem) based on richest habitat (RTH), qualitative multihabitat (QMH), or the combination of RTH and QMH (QQ) invertebrate samples. The BIR study was conducted in the Ridge and Valley ecoregion using coarse-grained riffles as the RTH habitat. The RAL study was conducted in the Piedmont ecoregion with coarse-grained riffles as the RTH habitat. The ATL study also was conducted in the Piedmont, but woody snags were the RTH habitat in these sandy-bottom streams. The best and most consistent models for all three areas were obtained from the QQ (RTH + QMH) samples, which are the most complete qualitative representation of the invertebrate assemblage at each study site. Models derived from single-habitat quantitative (RTH) samples did not perform as well as those based on qualitative multihabitat samples (QMH and QQ). In ATL, the UII explained 31% of the invertebrate response based on RTH samples from woody snags versus 69% based on the QQ samples. In all, the urban response-model was able to explain 69% (ATL), 78% (RAL), and 83% (BIR) of the variation in the biological responses based on the QQ samples. The response models for ATL, BIR, and RAL were applied to 294 sites in the South Atlantic gulf and Tennessee River basins. These sites were sampled as part of the NAWQA Program over the past decade using standardized sample collection, processing, and analysis techniques. The applicability of each model was assessed based on the deviation of the derived site score from the original response model and the deviation of the UII estimated by the response model from the UII derived from census, land-use, and infrastructure data. In general, the `best' response model was the one derived from sites that had similar natural environmental characteristics (e.g., basin size and ecoregion) to the site that was being modeled. Sites with widely different natural environmental characteristics tended to have fewer taxa in common with the underlying response model and deviated more from expected results. For example, the three response models were all developed from small basins and performed poorly when applied to large rivers. There was, however, a surprising amount of correspondence among the three models derived from QQ samples. The RAL data were adequately represented by the BIR and ATL models. The ATL model was well represented by the RAL model, but not by the BIR model. The general applicability of these biological-based models of urbanization to small streams throughout the South Atlantic gulf and Tennessee River basins indicates that a general model of urban effects can be developed for this area.
UR: http://nc.water.usgs.gov/albe/
DE: 0410 Biodiversity
DE: 0466 Modeling
DE: 0478 Pollution: urban, regional and global (0345, 4251)
DE: 0493 Urban systems
DE: 0496 Water quality
SC: Biogeosciences [B]
MN: Fall Meeting 2005