General Glossary

Animals without backbones that are not large enough to be seen
by the unaided eye; they will not be retained by a U.S. Standard
No. 30 sieve (28 meshes per inch, 0.595 mm openings).

Analysis techniques using several measurable characteristics of
a biological assemblage.

Statistical methods (such as ordination or discriminant
analysis) for analyzing physical and biological community data
using multiple variables.

General statements of attainable or attained conditions of
biological integrity and water quality for a given designated
aquatic life use.

National Pollutant Discharge Elimination System.

Numerical indices that describe expected attainable community
attributes for different designated aquatic life uses.

Aggregate of individuals of a biological species that are
geographically isolated from other members of the species and
are actually or potentially interbreeding.

Procedure for subdividing a geographic area into regions of
relative homogeneity in ecological systems or in relationship
between organisms and their environment

A grouping of organisms given a formal taxonomic name such as
species, genus, family.

The number of distinct species or taxa that are found in an
assemblage, community, or sample.