Primary purpose
To assess the biological integrity of a habitat using samples of living organisms and to evaluate the consequences of human actions on biological systems. Developed for use in managing aquatic resources (e.g., to establish use designations for water bodies, biological water quality standards, or goals for restoration).
Expertise needed
Biologists trained and experienced with biota being assessed (e.g., invertebrates, fish).
Applicable habitat types
Variety of habitats including streams, lakes, and wetlands.
Category assessed
Biological condition.
Procedure
The user(s) classifies environments to define homogeneous sets within or across ecoregions (e.g., streams, lakes, or wetlands; large or small streams). The "set" to be studied is identified (e.g., 2nd- to 4th order streams in southwestern Oregon). Attributes (metrics) are selected that provide reliable and relevant signals about the biological effects of human activities. For example, graphing existing data may show that the number of invertebrate taxa in streams is a reliable indicator of grazing intensity within a watershed. Sampling protocols and designs are developed that ensure that those metrics are measured accurately and precisely. Data is collected from each site and analyzed to determine the reference standard for each metric. The range of metric values are changed to converted metric scores of 1, 3, or 5. An index of biological integrity (IBI) is then calculated for each site.
Key Terminology
Attribute: measurable component of a biological system.
Biological integrity: the ability to support and maintain a balanced, integrated, adaptive biological system having the full range of elements (genes, species, and assemblages) and processes (mutation, demography, biotic interactions, nutrient and energy dynamics, and metapopulation processes) expected in a region’s natural habitat.
Converted metric score: score assigned to quantitative ranges for each metric depending upon the level of human activity. A site receives a score of 5 if the metric value lies at or near the value expected at a site minimally altered by humans, 3 if moderately degraded, or 1 if severely degraded.
Ecological indicators: diagnostic metrics through which biological integrity can be assessed. Ideally, these indicators must be sensitive to a range of stresses, able to distinguish stress-induced variation from natural variation, relevant to societal concerns, and easy to measure and interpret.
I
ndex of biological integrity (IBI): a multimetric index indicating the ability of a habitat to support and maintain a balanced, integrated, adaptive biological system having the full range of elements expected in a region’s natural habitat (IBI = sum of converted metric scores).
Metric: attribute empirically shown to change in value along a gradient of human influence.
Reference condition or baseline condition: the condition at a site with a biota that is the product of evolutionary and biogeographic processes in the relative absence of the effects of modern human activity. The IBI measures the biological well-being of sites against a regional reference condition.
Reference standard: the range of values measured for each metric at sites with the least amount of human activity (e.g., reference condition).
Contact person
James Karr, University of Washington, 151 Mechanical Engineering Building, Box 352200, Seattle, WA 98195-2200
phone: (206) 685-4784; fax: (206) 543-2025; e-mail: jrkarr@u.washington.edu
Doreen Vetter, US Environmental Protection Agency, Wetlands Division (4502F), 1200 Pennsylvania Ave., NW, Washington, D.C. 20460
Phone: (202) 250-1906; fax: (202) 260-8000; e-mail: vetter.doreen@epa.gov
Output
Measure of biological integrity of a site relative to the biological integrity of reference conditions sites from the same geographic region.
Estimated time to assess 1 acre site
Total 8 hours per site (if models are available)
8 hours per site: Conduct fieldwork (4 hours) and lab work (4 hours). Compare site to reference standard for each metric (during step 3).
Total 328 hours (if models must be developed)
320 hours [months of work]: Prepare for assessment (step 1), select measurable attributes (step 2), develop sampling protocols and designs (step 3), and devise analytical procedures (step 4).
8 hours per site: Conduct fieldwork (4 hours) and lab work (4 hours). Compare site to reference standard for each metric (during step 3).
Comparison of habitat types
Can directly compare similar habitats (same classification) within the same geographic region. Cannot directly compare different habitats (i.e., as defined by classification) or similar habitats from different regions.
Use as guide to design
IBI should not be used as a guide to design, but may be useful in guiding site selection. IBI uses samples of living organisms to assess biological integrity. It does not address or provide information on habitat structure or other elements important to design. IBI could be used to select restoration/creation sites. A high index near a potential site would indicate that the area is subject to minimal human influence and therefore has a good potential for successful creation. A low index at an existing site could indicate that it has good potential as a restoration site. Alternatively, a low index might suggest that an area is unsuitable for creation due to the level of human impact.
Related procedures
NEFWIBP (Hicks 1997) is directly related to, and may be considered a subset of IBI.
Extent of use/field testing
So far, IBI is in development for wetlands and has not been applied in a regulatory context. Several states are developing IBIs for their wetlands and are working directly through a the Biological Assessment of Wetlands Workgroup (BAWWG) which is coordinated by USEPA. Further description of the BAWWG, the development of IBIs in wetlands, and comparison between IBI and the HGM Approach are provided by Danielson (1998). IBI or conceptually similar approaches has been used to assess integrity of lotic fish in more than 20 states of the US and in various countries. Similar protocols (some using aquatic invertebrates or birds) have been developed for reservoirs, lakes, estuaries, wetlands, and riparian corridors (see references in Angermeier and Karr 1994; Karr and Chu 1998). IBI has been used as a conceptual framework for fish, aquatic and terrestrial invertebrates, birds, plants, algae, and others.
Proposed future revisions
Application of IBI for use in wetlands is under development in a number of states including Minnesota, Ohio, and North Dakota (Danielson 1998).
Key References
Karr, J.R. 1981. Assessment of biotic integrity using fish communities. Fisheries 6(6): 21-27.
Karr, J.R. and E.W. Chu. 1998. Restoring Life in Running Waters: Better Biological Monitoring. Island Press, Covelo, CA. 200 pp.
Karr, J.R. 1998 (In press). Rivers as sentinels: using the biology of rivers to guide landscape management. In R.J. Naiman and R.E. Bilby (eds). River Ecology and Management: Lessons from the Pacific Coastal Region, Springer-Verlag, NY.
Danielson, T.J. 1998. Wetland Bioassessment Fact Sheets. EPA 843-F-001. U.S. Environmental Protection Agency. Office of Wetlands, Oceans, and Watersheds, Wetlands Division, Washington, D.C. 22 pp.
Angermeier, P.L., and J.R. Karr. 1994. Biological integrity versus biological diversity as policy directives: Protecting biotic resources. BioScience 44(10):690-697.
Fore, L.S. and J.R. Karr. 1996. Assessing invertebrate responses to human activities: evaluating alternative approaches. J.N. Am. Benthol. Soc. 15(2):212-231.
Additional reference
Karr, J.R. and E.W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively. EPA 235-R97-001. University of Washington, Seattle, WA.