Chapter Four 



Application of the Indicator Evaluation Guidelines to a 



Multimetric Indicator of Ecological Condition 



Based on Stream Fish Assemblages 



Frank H. McCormick, U.S. EPA, National Exposure Research Laboratory, 



Ecological Exposure Research Division, Cincinnati, OH 



David V. Peck, U.S. EPA, National Health and Environmental Effects 



Research Laboratory, Western Ecology Division, Corvallis, OR 



In this chapter, we employ the guidelines presented in Chapter 1 to evaluate a connplex {i.e., multiple 

 components) indicator of ecological condition based on stream fish assemblages. This indicator is being 

 modified and developed for implementation in a specific monitoring effort (the Mid-Atlantic Highlands 

 Assessment, described below) designed to address specific regional-scale assessment questions. 



This chapter does not provide complete documentation of the Indicator or the process of its 

 development. Our primary intent is to provide examples of the type of information that is appropriate to 

 address each evaluation guideline for the indicator. In some cases, examples are presented based on 

 hypothetical or simulated data, and in some cases, not all available information pertinent to a comprehensive 

 evaluation is provided. More complete documentation of the development and evaluation of the suitability of 

 this indicator exists or will be forthcoming in various scientific journals. 



The indicator is a composite index, and its development is based on the multimetric Index of Biotic Integrity 

 (IB!) originally developed byKarr(Karr1981, Karrefa/. 1986). The IBI was developed to assess the condition 

 of water bodies by direct evaluation of biological attributes (Karr 1981, Karr and Dudley 1981, Karr 1991). 

 Multimetric indicators such as the IBI are based on the premise that biological data represent a means to 

 integrate various structural and functional attributes of an ecosystem and provide an overall assessment of 

 ecosystem condition (Fausch et al. 1990, Karr 1991, Karr and Chu 1997). Biological and socioeconomic 

 characteristics of stream fish assemblages, including the capability to integrate the effects of a variety of 

 stressors across different time scales and levels of ecological organization, and the importance and familiarity 

 of fishes to the general public, make them conducive to the development of an indicator of ecological condition 

 (Table 4-1). 



Some important features of the indicator are presented in Table 4-2. The development of the indicator is 

 based on accepted ecological and mathematical principles. Various critical structural and functional attributes 

 of the biotic components of an ecosystem (e.g., taxonomic richness, trophic structure) believed to respond 

 predictably to increasing intensities of human disturbance are represented by different metrics (Karr 1986, 

 Karr 1 991 , Barbour et al. 1 995). Metrics are derived from species composition and relative abundance data 

 of a particular ecological assemblage or community (stream fish in this example) collected at individual 

 sampling sites. A final suite of metrics is selected for use in developing the indicator, based on responsiveness 



4-1 



