Tuesday, June 5, 2007
559

Small changes in a hostile environment: A GIS based approach to predicting macroinvertebrate community response to suburban development levels in Austin, Texas

Andrew York Clamann and Mateo Scoggins. Watershed Protection and Development Review Department, City of Austin, 505 Barton Springs Road, ERM, 11th floor, Austin, TX 78704

The City of Austin collected over 468,000 benthic macroinvertebrates at 293 sites in its stream monitoring efforts from 1993-2007, a period of unprecedented population growth.  This large data set provides an excellent opportunity for comprehensive analysis of spatial and temporal trends in organismal distribution on a relatively small spatial scale.  Although changes in benthic communities are clearly demonstrated in urban areas, it is difficult to substantiate degradation of biotic integrity in areas with less than 15% impervious cover, due to high natural variability in hydrology and geomorphology in Central Texas streams.  Extensive water chemistry and GIS databases were used as explanatory variables for distribution of relatively intolerant taxa along spatial and temporal development scales.  Resulting indicator taxa and community associations appear to be more sensitive predictors of low or early levels of degradation than the multi-metric index approach that is currently being used by the City of Austin.  As the suburban fringe of cities continues to expand, this fine grain, GIS approach may provide a quantitative assessment tool for resource managers at the local scale to detect subtle impacts on benthic communities.

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