Multi-regional synthesis of temporal trends in biotic assemblages in streams and rivers of the continental United States

Scientific Investigations Report 2013-5046

National Water-Quality Assessment (NAWQA) Program
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Biotic assemblages in aquatic ecosystems are excellent integrators and indicators of changing environmental conditions within a watershed. Therefore, temporal changes in abiotic environmental variables often can be inferred from temporal changes in biotic assemblages. Algae, macroinvertebrate, and fish assemblage data were collected from 91 sampling sites in 4 geographic regions (northeastern/north-central, southeastern, south-central, and western), collectively encompassing the continental United States, from 1993 to 2009 as part of the U.S. Geological Survey National Water-Quality Assessment Program. This report uses a multivariate approach to synthesize temporal trends in biotic assemblages and correlations with relevant abiotic parameters as a function of biotic assemblage, geographic region, and land use. Of the three groups of biota, algal assemblages had temporal trends at the greatest percentage of sites. Of the regions, a greater percentage of sites in the northeastern/north-central and western regions had temporal trends in biotic assemblages. In terms of land use, a greater percentage of watersheds draining agricultural, urban, and undeveloped areas had significant temporal changes in biota, as compared to watersheds with mixed use. Correlations between biotic assemblages and abiotic variables indicate that, in general, macroinvertebrate assemblages correlated with water quality and fish assemblages correlated with physical habitat. Taken together, results indicate that there are regional differences in how individual biotic assemblages (algae, macroinvertebrates, and fish) respond to different abiotic drivers of change.

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USGS Numbered Series
Multi-regional synthesis of temporal trends in biotic assemblages in streams and rivers of the continental United States
Series title:
Scientific Investigations Report
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Year Published:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Utah Water Science Center, National Water Quality Assessment Program
vi, 22 p.
United States
Other Geospatial:
Continental United States
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