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Influence of environmental factors on biotic responses to nutrient enrichment in agricultural streams

Journal of the American Water Resources Association

By:
, , and
DOI: 10.1111/j.1752-1688.2010.00430.x

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Abstract

The influence of environmental factors on biotic responses to nutrients was examined in three diverse agricultural regions of the United States. Seventy wadeable sites were selected along an agricultural land use gradient while minimizing natural variation within each region. Nutrients, habitat, algae, macroinvertebrates, and macrophyte cover were sampled during a single summer low-flow period in 2006 or 2007. Continuous stream stage and water temperature were collected at each site for 30 days prior to sampling. Wide ranges of concentrations were found for total nitrogen (TN) (0.07-9.61 mg/l) and total phosphorus (TP) (<0.004-0.361 mg/l), but biotic responses including periphytic and sestonic chlorophyll a (RCHL and SCHL, respectively), and percent of stream bed with aquatic macrophyte (AQM) growth were not strongly related to concentrations of TN or TP. Pearson's coefficient of determination (R2) for nutrients and biotic measures across all sites ranged from 0.08 to 0.32 and generally were not higher within each region. The biotic measures (RCHL, SCHL, and AQM) were combined in an index to evaluate eutrophic status across sites that could have different biotic responses to nutrient enrichment. Stepwise multiple regression identified TN, percent canopy, median riffle depth, and daily percent change in stage as significant factors for the eutrophic index (R2 = 0.50, p < 0.001). A TN threshold of 0.48 mg/l was identified where eutrophic index scores became less responsive to increasing TN concentrations, for all sites. Multiple plant growth indicators should be used when evaluating eutrophication, especially when streams contain an abundance of macrophytes.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Influence of environmental factors on biotic responses to nutrient enrichment in agricultural streams
Series title:
Journal of the American Water Resources Association
DOI:
10.1111/j.1752-1688.2010.00430.x
Volume
46
Issue:
3
Year Published:
2010
Language:
English
Publisher:
American Water Resources Association
Publisher location:
Middleburg, VA
Contributing office(s):
Idaho Water Science Center
Description:
16 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of the American Water Resources Association
First page:
498
Last page:
513
Country:
United States
State:
Arkansas;Idaho;Minnesota;Missouri;Nevada;Oklahoma;Wisconsin