Jump to main content or area navigation.

Contact Us

Water: Monitoring & Assessment

Wetlands - Wetland Bioassessment Glossary


Wetland Bioassessment Glossary

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 wetland or other habitat. Examples of assemblages used for biological assessments include: algae, amphibians, birds, fish, 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. EPA Office of Science and Technology's Health and Ecological Criteria Division's Biological Criteria Fact Sheet provides more information on this topic.

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). Key Concepts for Using Watershed Biological Indicators provides more information on this topic.

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 taxonomic 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.


Statements of the conditions presumed to support or protect the designated use or uses of a waterbody. Criteria may be narrative or numeric. The singular form is criterion.

Designated Use

Classification designated in water quality standards for each waterbody or segment that defines the optimal purpose for that waterbody. Examples are 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 has 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.


A region defined by similarity of climate, landform, soil, potential natural vegetation, hydrology, and other ecologically relevant variables.


The roles that wetlands serve, which are of value to society or environment.

Functional Groups

A means of dividing organisms into groups, 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. More information may be found on the multi-agency site, Hydrogeomorphic Approach to Assessing Wetland Functions. Exit EPA Disclaimer

Hydrogeomorphic (HGM) Approach

A method that compares a wetland's functions (e.g., water retention, nutrient cycling) to similar wetlands of the same type (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). More information may be found on the multi-agency site, Hydrogeomorphic Approach to Assessing Wetland Functions. Exit EPA Disclaimer


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 of Biological Integrity

An integrative expression of site condition across multiple metrics. An index of biological integrity is often composed of at least seven metrics. (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 plural form is either indices or indexes.

Index of Biological Integrity

An integrative expression of the biological condition that is composed of multiple metrics. Similar to economic indexes 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 (Section 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.


A grouping of organisms given a formal taxonomic name such as species, genus, family, etc. The singular form is taxon.

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. EPA's Office of Science and Technology's Water Quality Criteria and Standards Program site provides more information.


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, and 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)

Jump to main content.