Mary Freeman Byron J. Freeman Jane E. Argentina 2010 The aquatic macrophyte <i>Podostemum ceratophyllum</i> (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 <i>P. ceratophyllum</i> 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 <i>P. ceratophyllum</i> 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 (&ge;50%)<i>P. ceratophyllum</i> 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. <i>Podostemum ceratophyllum</i> 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 <i>P. ceratophyllum</i> 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. application/pdf en Humboldt Field Research Institute Predictors of occurrence of the aquatic macrophyte <i>Podostemum ceratophyllum</i> in a southern Appalachian River article