Guideline 15: Linkage to Management Action 



Ultimately, an indicator is useful only if it can provide information to support a management decision or to 

 quantify the success of past decisions. Policy makers and resource managers must be able to recognize 

 the implications of indicator results for stewardship, regulation, or research. An indicator with practical 

 application should display one or more of the following characteristics: responsiveness to a specific 

 stressor, linkage to policy indicators, utility in cost-benefit assessments, limitations and boundaries of 

 application, and public understanding and acceptance. Detailed consideration of an indicator's 

 management utility may lead to a re-examination of its conceptual relevance and to a refinement of the 

 original assessment question. 



Performance Objective 



1. Demonstrate how indicator values are to be interpreted and used to make management decisions 

 related to relative condition or risk. 



Data derived from this indicator have not been assembled for management use, but EMAP has advanced an 

 approach (e.g., Paulsen etal. 1991, U.S. EPA 1997) to present information regarding the status of resource 

 populations with respect to ecological condition (Fig. 4-10). Procedures are available (Diaz-Ramos et al. 

 1996) for developing cumulative distribution functions (cdfs) that show the proportion of a target resource 

 population (estimated as lengths of target stream resource) that is at or below any specific value of the 

 indicator (e.g., a threshold value for impaired condition). Additional information regarding uncertainty is 

 presented by computing confidence bounds about the cdf curve (e.g., Diaz-Ramos et al. 1996, Stewart- 

 Oaten 1996). In the example (Fig. 4-10), a threshold value of 50 (see Guideline 14, Table 4-20) is used to 

 distinguish impaired condition. Approximately 30 percent (with 95 percent confidence bounds of approximately 

 ±8 percent) of the target resource population has indicator values at or below the threshold value. 



Information regarding relative risks from different stressors can be obtained using a similar approach {i.e., 

 developing cdf curves and evaluating the proportion of the target resource population that is at or below some 

 threshold of impairment). Figure 4-1 1 presents an example showing the relative ranking of different stressors, 

 based on the 1993-1994 MAHA study. Introduced fish species (based on presence) and watershed-level 

 disturbances are the most regionally extensive stressors in the MAHA region, whereas acidic deposition, a 

 larger-scale stressor, has a much lower impact across the region than might be expected. Once a suitably 

 responsive indicator has been developed, association or contingency analysis of indicator values (or condition 

 classes) and regionally important stressor variables (or impact classes) can be used to identify potential 

 sources of impairment in condition. These analyses have not yet been conducted for the indicator, pending 

 further research to improve the responsiveness of the indicator. 



Summary 



Approaches developed for EMAP can be used to graphically present results relating the distribution of indicator 

 values (and corresponding condition classes) across a target resource population. Relative impact of various 

 stressors on resource populations can also be determined and presented graphically. The combination of 

 these two tools allows for the estimation of the status of resource populations with respect to ecological 

 condition, and provides some indication of potential causes of impaired condition. Results from this indicator 

 of biotic integrity can be used in the development of resource policy. 



4-40 



