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Glossary of Wetland Bioassessment Terms

United States Environmental Protection Agency
Office of Water
Office of Wetland, Oceans and Watersheds (4502-F)
July 1998

Wetland Bioassessment Fact Sheet 10

ambient monitoring
Monitoring within natural systems (e.g., lakes, rivers, estuaries, wetlands) to determine existing conditions.
An association of interacting populations of organisms in a given waterbody. Examples of assemblages used for biological assessments include : algae, amphibians, birds, fish, herps (reptiles and amphibians), macroinvertebrates (insects, crayfish, clams, snails, etc.), and vascular plants.
A measurable component of a biological system. (Karr, J.R., and E.W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively. EPA 235-R97-001. University of Washington, Seattle)
biological assessment (bioassessment)
Using biomonitoring data of samples of living organisms to evaluate the condition or health of a place (e.g., a stream, wetland, or woodlot).
biological criteria (biocriteria)
Numerical values or narrative expressions that describe the condition of aquatic, biological assemblages of reference sites of a given aquatic life use designation.
biological integrity
"...the ability of an aquatic ecosystem to support and maintain a balanced, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of natural habitats within a region." (Karr, J. R. and D. R. Dudley. 1981. Ecological perspective on water quality goals. Environmental Management 5:55-68)
biological monitoring (biomonitoring)
Sampling the biota of a place (e.g., a stream, a woodlot, or a wetland)
The plants and animals living in a habitat.
composition (structure)
The composition of the taxanomic grouping such as fish, algae, or macroinvertebrates relating primarily to the kinds and number of organisms in the group.
All the groups of organisms living together in the same area, usually interacting or depending on each other for existence.
criteria (singular criterion)
Statements of the conditions presumed to support or protect the designated use or uses of a waterbody. Criteria may be narrative or numeric.
designated Use
Classification designated in water quality standards for each waterbody or segment that defines the optimal purpose for that waterbody. Examples - drinking water use and aquatic life use.
Microscopic algae with cell walls made of silicon and of two separating halves.
A combination of the number of taxa (see taxa richness) and the relative abundance of those taxa. A variety of diversity indexes have been developed to calculate diversity.
ecological assessment
A detailed and comprehensive evaluation of the status of a water resource system designed to detect degradation and if possible, to identify causes of that degradation.
ecological integrity
The condition of an unimpaired ecosystem as measured by combined chemical, physical (including physical habitat), and biological attributes.
Regions defined by similarity of climate, landform, soil, potential natural vegetation, hydrology, and other ecologically relevant variables.
A role that wetlands serve, which is of value to society or environment.
functional group
A means of classifying organisms, often based on their method of feeding (e.g., shredder, scraper, filterer, predator), type of food (e.g., fruit, seeds, nectar, insects), or habits (e.g., burrower, climber, clinger).
The sum of the physical, chemical, and biological environment occupied by individuals of a particular species, population, or community.
Reptiles and amphibians.
hydrogeomorphic (HGM)
Classification: A wetland classification system based on the position of a wetland in the landscape (geomorphic setting), dominant sources of water, and the flow and fluctuation of water once in the wetland. Hydrogeomorphic classes include riverine, depressional, slope, mineral soil flats, organic soil flats, estuarine fringe, and lacustrine fringe.
hydrogeomorphic (HGM) approach
A functional assessment method which compares a wetland's condition to similar wetland types (as defined by HGM classification) that are relatively unaltered. HGM functions normally fall into one of three major categories: (1) hydrologic (e.g., storage of surface water), (2) biogeochemical (e.g., removal of elements and compounds), and (3) habitat (e.g., maintenance of plant and animal communities).
The science of dealing with the properties, distribution, and circulation of water both on the surface and under the earth.
A change in the chemical, physical (including habitat), or biological quality or condition of a waterbody caused by external forces.
A detrimental effect on the biological integrity of a waterbody caused by an impact that prevents attainment of the designated use.
index (plural indexes or indices)
An integrative expression of site condition across multiple metrics. An index of biological integrity is often composed of at least 7 metric. (Karr, J.R., and E.W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively. EPA 235-R97-001. University of Washington, Seattle)
Index of Biological Integrity (IBI)
An integrative expression of the biological condition that is composed of multiple metrics. Similar to the Dow Jones Industrial index used for expressing the condition of the economy.
Animals without backbones that can be seen with the naked eye (caught with a 1 mm2 mesh net). Includes insects, crayfish, snails, mussels, clams, fairy shrimp, etc.
An attribute with empirical change in value along a gradient of human influence. (Karr, J.R., and E.W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively. EPA 235-R97-001. University of Washington, Seattle)
The Clean Water Act (§502.19) defines pollution as "the [hu]man-made or [hu]man-induced alteration of chemical, physical, biological, and radiological integrity of water."
reference condition
Set of selected measurements or conditions of minimally impaired waterbodies characteristic of a waterbody type in a region.
reference site
A minimally impaired site that is representative of the expected ecological conditions and integrity of other sites of the same type and region.
taxa (singular taxon)
A grouping of organisms given a formal taxonomic name such as species, genus, family, etc.
taxa richness
The number of distinct species or taxa that are found in an assemblage, community, or sample.
water quality standard
A legally established state regulation consisting of three parts: (1) designated uses, (2) criteria, and (3) antidegradation policy (See Factsheet 7).
Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, an similar areas. (Cowardin et al. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Department of the Interior. Fish and Wildlife Service. FWS/OBS-79/31)