Georgia Water Science Center
This report is available online in pdf format (2 Mb): USGS SIR 2008-5046
Daniel L. Calhoun, M. Brian Gregory, and Holly S. Weyers
U.S. Geological Survey Scientific Investigations Report 2008-5046, 33 pages (Published May 2008)
Benthic algal and invertebrate communities in two
Coastal Plain regions of the Eastern United States—the
Delmarva Peninsula (27 sites) and Georgia Upper Coastal
Plain (29 sites)—were assessed to determine if aspects of
agricultural land use and nutrient conditions (dissolved and
whole-water nitrogen and phosphorus) could be linked to
biological community compositions. Extensive effort was made to compile
land-use data describing the basin and riparian conditions at
multiple scales to determine if scale played a role in these
relations. Large differences in nutrient condition were found
between the two study areas, wherein on average, the Delmarva
sites had three times the total phosphorus and total
nitrogen as did the sites in the Georgia Upper Coastal Plain.
A statistical approach was undertaken that included multivariate
correlations between Bray-Curtis similarity matrices of
the biological communities and Euclidean similarity matrices
of instream nutrients and land-use categories. Invertebrate
assemblage composition was most associated with land use
near the sampled reach, and algal diatom assemblage composition
was most associated with land use farther from the
streams and into the watersheds. Link tree analyses were
conducted to isolate portions of nonmetric multidimensional
scaling ordinations of community compositions that could
be explained by break points in abiotic datasets. Invertebrate
communities were better defined by factors such as agricultural
land use near streams and geographic position. Algal
communities were better defined by agricultural land use at
the basin scale and instream nutrient chemistry. Algal autecological
indices were more correlated with gradients of nutrient
condition than were typically employed invertebrate metrics
and may hold more promise in indicating nutrient impairment
in these regions. Nutrient conditions in the respective study
areas are compared to draft nutrient criteria established by the
U.S. Environmental Protection Agency. Substantial reductions
in some nutrients would be required to meet proposed reference
conditions on the Delmarva Peninsula.
Abstract
Introduction
Purpose and Scope
Study Areas
Acknowledgments
Site Selections
Data Collection and Processing
Habitat
Water Chemistry
Benthic Algae
Invertebrates
Basin and Riparian Land-Use Analysis
Statistical Analyses
Stream Habitat, Nutrients, and Community Composition in Agricultural Streams
Habitat
Nutrients
Nutrient Loadings
Invertebrate and Algal Communities
Linking Environmental Variables to Biological Communities
Summary and Conclusions
References
Appendix A. Variables determined by LINKTREE Procedures, Algal and Invertebrate Indices, and Abiotic Variables for the Delmarva Peninsula Study as Illustrated in Figures 3 and 5
Appendix B. Variables determined by LINKTREE Procedures, Algal and Invertebrate Indices, and Abiotic Variables for the Georgia Upper Coastal Plain Study as Illustrated in Figures 4 and 6
This report is available online in pdf format (2 Mb): USGS SIR 2008-5046
To view the PDF document, you need the Adobe Acrobat® Reader installed on your computer. (A free copy of the Acrobat® Reader may be downloaded from Adobe Systems Incorporated.)
Suggested citation:
Calhoun, D.L., Gregory, M.B., and Wyers, H.S., 2008, Algal and invertebrate community composition along agricultural gradients—A comparative study from two regions of the Eastern United States: U.S. Geological Survey Scientific Investigations Report 2008–5046, 33 p., also available online at http://pubs.usgs.gov/sir/2008/5046
Recent USGS publications for Georgia or Georgia Water-Resources Information
For more information, please contact webmaster-ga@usgs.gov.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/sir/2008/5046/index.html
Page Contact Information: Publications Team
Page Last Modified: Thursday, 10-Jan-2013 18:45:07 EST
