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THE RESPONSE OF BIOLOGICAL, CHEMICAL, AND HABITAT METRICS TO WATERSHED URBANIZATION IN NEW ENGLAND WADABLE STREAMS
27th Annual Meeting of the New England Association of Environmental Biologists (NEAEB), 2003
James Coles, Thomas Cuffney, Gerard McMahon, Karen Beaulieu, Laura Hayes, Keith Robinson, and Jeffrey Deacon
U.S. Geological Survey, 361 Commerce Way, Pembroke, NH 03275
Responses of biological communities (invertebrates, fish, and algae), physical habitat, and water chemistry to urbanization were compared among 30 streams within 75 miles of Boston, Massachusetts, during August 2000. Sampling sites were chosen to represent a gradient of urbanization, while minimizing natural variability among drainage basins. The study was designed to represent the effects of drainage basin urbanization occurring over time by using spatial differences as surrogates for temporal changes. The degree of urbanization for each drainage basin was characterized with a standardized urban index (0 – 100, lowest to highest) derived from 24 land cover, infrastructure, and socioeconomic variables. Urban index values were compared with biological, chemical, and habitat data by means of multivariate and multimetric analyses to determine how the data responded to changes in urbanization. Although the multivariate ordinations revealed strong responses between each of the biological, chemical, and habitat datasets and urbanization, only the results of selected metrics that were strongly responsive to urbanization are presented here. Metrics that were most generally responsive to the urban index for each data set included: EPT taxa and non-insect taxa for invertebrates; cyprinid taxa for fish; diatom taxa for algae; alkalinity, conductivity, and nitrogen for chemistry; and water depth and temperature for physical habitat. The slope of the responses often were higher between the urban index values from 0 to 35, suggesting that aquatic health may change the most between low to moderate levels of urbanization, and that there is comparatively little change from moderate to high levels of urbanization.
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