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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Urban Ecology I
SPATIAL AND TEMPORAL VARIATION IN BENTHIC MACROINVERTEBRATE ASSEMBLAGES IN AN URBAN RIVER BASIN.
J.K. Jackson, D.A. Lieb, and B.W. Sweeney. Stroud Water Research Center, Avondale, PA 19311 USA
The Schuylkill River Basin (4950 km2) provides drinking water as well as recreational, agricultural, and industrial resources for 3 million people in the Philadelphia metropolitan area. We used 5 years (1996-2000) of macroinvertebrate data from 19 sites to assess water/habitat quality across the basin and to evaluate the utility of quantitative, family-level data produced by undergraduates/volunteers. These 19 sites were on major tributaries or branches, and their watersheds represented 57% of total basin area. Spatial and temporal patterns were examined using the Macroinvertebrate Aggregated Index for Streams (MAIS) as well as commonly used individual biometrics and density of individual macroinvertebrate families or groups of families. MAIS Scores averaged across all five years revealed four statistically distinct groups of sites, from clearly impaired to relatively unimpaired. The most impaired sites had 33-53% fewer taxa, including 62-83% fewer EPT taxa and 55-70% fewer pollution intolerant taxa relative to the least impaired sites. Annual variation was great enough to affect site assessments for individual years. Most sites where macroinvertebrate assemblages indicated low or very low water/habitat quality were in watersheds with significant urban or mining development. Biometrics did not differentiate between urban and mining sites, but density measures provided some separation.
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