Utility Indices  
   
Vulnerability Indices  
   
How to cite this document  
   
Authors  


UTILITY INDICES
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Components of Utility Indices:


1. Exposure Potential

A measure of the likelihood of an individual encountering a contaminant by oral, dermal, or inhalation routes of exposure.

Specific elements that may affect exposure may include dietary preference, habitat preference, longevity, foraging technique, and other behaviors that result in contact with the physical environment.

Elements for exposure potential will vary among Utility indices.

 

2. Geographic Occurrence

The range and seasonal occurrence within a particular study area.

Species that are considered more desirable for monitoring occur throughout a greater portion of the study area, spend a greater amount of their life cycle in the study area, and breed, rather than just winter, in the study area.

 

3. Ease of Collection

Ease of collection is determined by a species’ social structure, accessibility, ease of capture, abundance, and management status. The season during which the collection will occur may influence results (e.g., a population may be highly colonial during the breeding season, yet employ a looser social structure during winter months)

Accessibility is classified in relative terms, simply as “easy,” “moderate,” or difficult.” These loosely defined terms permit users to rate accessibility based on the specific circumstance, taking into account monetary, personnel, equipment, and other logistical constraints.

Abundance and management status includes restrictions on collection or disturbance based upon state or federal regulations protection measures or management protocols.

Species are considered easier to collect if they nest or roost colonially and breed in the study area, making collections of eggs or young for contaminant or biomarker analysis possible (persistent organic pollutants, mercury, and cholinesterase-inhibiting pesticides only).

 

4. Quantity Of Existing Exposure And Effects Data

The amount of information available for a species in regard to the particular contaminant or contaminant class. Data sources may include hypothesis-driven laboratory or field investigations, or other types of monitoring efforts. Species for which relatively greater amounts of data exist for the contaminant of concern are given more weight as sentinels. The existence of baseline data and historical precedent are considered advantageous for bioindicator species in that such data facilitates comparison to affected conditions.


5. Calculation of Utility Index Scores

The four components are summed, each carrying equal weight regardless of the number of elements:

Utility Index Score = (Exposure Potential) + (Geographic Occurrence) +
(Ease of Collection) + (Quantity of Existing Data)

Each component carries a value between 1 and 5 points. Elements within components are weighted equally (1-5 points), with the exception of “Dietary Preference” and “Foraging Technique” within the Exposure Potential component, which carry a maximum value of 10 points. These two elements are weighted more heavily as they generally represent the principal route of toxicant exposure for terrestrial vertebrates. The final Utility Index score ranges between 4 and 20

Roll over the Index Name with your mouse for specific point values of each element in the table below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Utility Index
Equation
 
  VULNERABILITY INDICES
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Components of Vulnerability Indices:


1. Exposure Potential

A measure of the likelihood of an individual encountering a contaminant by oral, dermal, or inhalation routes of exposure.

Specific elements that may affect exposure of both the individual and population may include: dietary preference, habitat preference, longevity, foraging technique, other behaviors that result in contact with the environment, amount of time spent on the study area, and distribution throughout the study area.

Elements of individual exposure potential (e.g., dietary and habitat preference, longevity, foraging technique) will vary among Vulnerability indices. Elements that affect the exposure of the population (i.e., time spent in study area, distribution throughout study area) will remain the same among Vulnerability Indices.


2. Sensitivity

An individual’s likelihood to sustain damage from exposure to a contaminant. Elements of sensitivity will differ among Vulnerability Indices based partially on the mechanism of action of the toxicant.


3. Resilience of a population

The ability to recover following a harmful exposure, based on: abundance within and outside the study area, reproductive potential, and age of individuals at first breeding.

 

4. Calculation of Vulnerability Index Scores

The three components are summed, giving more weight to the first component
o It is assumed that if a species is unlikely to be exposed, it is not highly vulnerable regardless of individual sensitivity or population resilience


Vulnerability Index Score = 2 (Exposure Potential) + (Sensitivity) + (Resilience of Population)

Elements within components are weighted equally (1-5 points), with the exception of “Dietary Preference” and “Foraging Technique” within the Exposure Potential component, which carry a maximum value of 10 points. These elements are weighted more heavily as they generally represent the principal route of toxicant exposure for terrestrial vertebrates. The Vulnerability Index yields a score between 4 and 20

Roll over the Index Name with your mouse for specific point values of each element in the table below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Vulnerabilty Index Equations

 

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  HOW TO CITE THIS DOCUMENT
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Please use the following citation when referring to this document:

Golden, N.H., B.A. Rattner, and J.B. Cohen. 2003. Ranking Terrestrial Vertebrate Species for Utility in Biomonitoring and Vulnerability to Environmental Contaminants. [Updated July 2003; cited *]. U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland. Available from: http://www.pwrc.usgs.gov/ceetv/

* enter the date you actually visited the website.

 
 
AUTHORS

USGS Patuxent Wildlife Research Center

Barnett A. Rattner
Nancy H. Golden

Jonathan B. Cohen

 

 

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