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Predictors of occurrence of the aquatic macrophyte Podostemum ceratophyllum in a southern Appalachian River

Southeastern Naturalist

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Abstract

The aquatic macrophyte Podostemum ceratophyllum (Hornleaf Riverweed) commonly provides habitat for invertebrates and fishes in flowing-water portions of Piedmont and Appalachian streams in the eastern US. We quantified variation in percent cover by P. ceratophyllum in a 39-km reach of the Conasauga River, TN and GA, to test the hypothesis that cover decreased with increasing non-forest land use. We estimated percent P. ceratophyllum cover in quadrats (0.09 m2) placed at random coordinates within 20 randomly selected shoals. We then used hierarchical logistic regression, in an information-theoretic framework, to evaluate relative support for models incorporating alternative combinations of microhabitat and shoal-level variables to predict the occurrence of high (≥50%)P. ceratophyllum cover. As expected, bed sediment size and measures of light availability (location in the center of the channel, canopy cover) were included in best-supported models and had similar estimated-effect sizes across models. Podostemum ceratophyllum cover declined with increasing watershed size (included in 8 of 13 models in the confidence set of models); however, this decrease in cover was not well predicted by variation in land use. Focused monitoring of temporal and spatial trends in status of P. ceratophyllum are important due to its biotic importance in fast-flowing waters and its potential sensitivity to landscape-level changes, such as declines in forested land cover and homogenization of benthic habitats.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Predictors of occurrence of the aquatic macrophyte Podostemum ceratophyllum in a southern Appalachian River
Series title:
Southeastern Naturalist
Volume
9
Issue:
3
Year Published:
2010
Language:
English
Publisher:
Humboldt Field Research Institute
Publisher location:
Steuben, ME
Contributing office(s):
Patuxent Wildlife Research Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Southeastern Naturalist
First page:
465
Last page:
476
Number of Pages:
12
Country:
United States