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Definitions
To effectively use biological criteria, a clear understanding of how these criteria are developed and applied in a water quality standards framework is necessary. This requires, in part, that users of biological criteria start from the same frame of reference. To help form this frame of reference, the following definitions are provided. Please consider them carefully to ensure a consistent interpretation of this document.
Definitions
An AQUATIC COMMUNITY is an association of interacting populations of aquatic organisms in a given waterbody or habitat.
A BIOLOGICAL ASSESSMENT is an evaluation of the biological condition of a waterbody using biological surveys and other direct measurements of resident biota in surface waters.
BIOLOGICAL CRITERIA, or biocriteria, are numerical values or narrative expressions that describe the reference biological integrity of aquatic communities inhabiting waters of a given designated aquatic life use.
BIOLOGICAL INTEGRITY is functionally defined as the condition of the aquatic community inhabiting unimpaired waterbodies of a specified habitat as measured by community structure and function.
BIOLOGICAL MONITORING is the use of a biological entity as a detector and its response as a measure to determine environmental conditions. Toxicity tests and biological surveys are common biomonitoring methods.
A BIOLOGICAL SURVEY, or biosurvey, consists of collecting, processing and analyzing representative portions of a resident aquatic community to determine the community structure and function.
A COMMUNITY COMPONENT is any portion of a biological community. The community component may pertain to the taxomonic group (fish, invertebrates, algae), the taxonomic category (phylum, order, family, genus, species), the feeding strategy (herbivore, omnivore, carnivore) or organizational level (individual, population, community association) of a biological entity within the aquatic community.
REGIONS OF ECOLOGICAL SIMILARITY describe a relatively homogeneous area defined by similarity of climate, landform, soil, potential natural vegetation, hydrology, or other ecologically relevant variable. Regions of ecological similarity help define the potential for designated use classifications of specific waterbodies.
DESIGNATED USES are those uses specified in water quality standards for each waterbody or segment whether or not they are being attained.
An IMPACT is a change in the chemical, physical or biological quality or condition of a waterbody caused by external sources.
An IMPAIRMENT is a detrimental effect on the biological integrity of a waterbody caused by an impact that prevents attainment of the designated use.
A POPULATION is an aggregate of interbreeding individuals of a biological species within a specified location.
A WATER QUALITY ASSESSMENT is an evaluation of the condition of a waterbody using biological surveys, chemical-specific analyses of pollutants in waterbodies, and toxicity tests.
An ECOLOGICAL ASSESSMENT is an evaluation of the condition of a waterbody using water quality and physical habitat assessment methods.