Variable Assemblage Responses to Multiple Disturbance Gradients: Case Studies in Oregon and Appalachia, USA
In the past 20 years, assessing biological condition through biological monitoring has assumed a more prominent position alongside chemical assessments of water quality. There has been a gradual evolution within federal and state water resource agencies to consider degradation to include physical habitat loss, adverse biological changes, and chemical alteration. As a result, much recent effort has been directed toward the development of multimetric indices of biotic integrity (IBIs) for various aquatic and riparian indicator taxa, particularly fish (Karr et al., 1986; Simon, 1999),
benthic macroinvertebrates (Kerans and Karr, 1994; Fore et al., 1996), algae (Hill et al., 2000; Fore, Chapter 22, this volume), and riparian birds and mammals (Brooks et al., 1991; O’Connell et al., 1998). Models predicting particular species from known environments compared against observed species also have been used for benthic macroinvertebrates (Wright, 1995; Norris and Hawkins, 2000).