Figure 4-3. Range of ecological condition (as expressed by biotic integrity) over which 

 individual metrics comprising the indicator are expected to respond 

 [Modified from Karr and Angemeier (1986) and Karr (1991)]. 



Summary 



Conceptual linkages between air, land and stream stressors of stream ecosystems with riparian, water column 

 and benthic receptors are presented. Principal stressor types include chemical, biological, hydrologic and 

 physical habitat alterations. Two different approaches were used to demonstrate conceptual linkages between 

 principal stressors believed to cause impairment with respect to the societal value of interest (biological 

 integrity), ecosystem responses to these stressors, and the indicator (or its components). 



4-11 



