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Environmental indicators of macroinvertebrate and fish assemblage integrity in urbanizing watersheds
Citation:
WALTERS, DAVID M., A. ROY, AND D. Leigh. Environmental indicators of macroinvertebrate and fish assemblage integrity in urbanizing watersheds. ECOLOGICAL INDICATORS. Elsevier Science Ltd, New York, NY, 9(6):1222-1233, (2009).
Impact/Purpose:
Our objectives were to identify the indicators of macroinvertebrate and fish integrity from a large set of best land cover geomorphology, and water quality variables, and to evaluate the potential for variables measured with minimal cost and effort to effectively preict biotic integrity. Macroinvertebrate descriptors were better predicted by land cover whereas fish descriptors were better predicted by geomorphology. Water quality variables demonstrated moderate levels of predictive power for biotic descriptors. Macroinvertebrate descriptors were best predicted by urban cover, conductivity, fines in riffles, and local relief. Fish descriptors were best predicted by embeddedness, turbidity, slope and forest cover. Comprehensive multiple linear regression models explained 63-81% fo the variation among descriptors, indicating strong relationships between landscape properties and biotic assemblages across our sites. Management and GIS models were weaker than comprehensive models, but were surprisingly robust, explaining 48-79% and 42-79%, respectively, of the variance among descriptors. Considering the relative strength of these models, we recommend a tiered approach to variable selection and model development depending upon management goals. GIS variables are simple and inexpensive to collect, and a GIS-based modeling approach would be appropriate for goals such as site-screening. As management goals become more complex, additional, easily-collected field variables should be included. Finally, labor-intensive variables could be added to meet complex management goals such as restoration of impaired streams or mechanistic studies of land use effect on stream ecosystems.
Description:
Urbanization compromises the biotic integrity and health of streams, and indicators of integrity loss are needed to improve assessment programs and identify mechanisms of urban effects. We investigated linkages between landscapes and assemblages in 31 wadeable Piedmont streams in the Etowah River basin in northern Georgia, USA.