General Glossary

Association of interacting assemblages in a given waterbody, the
biotic component of an ecosystem.

An association of interacting populations of organisms in a
given waterbody. Examples of assemblages used for biological
assessments include: algae, amphibians, birds, fish, reptiles
and amphibians, macroinvertebrates (insects, crayfish, clams,
snails, etc.), and vascular plants.

A measurable component of a biological system.

Animals without backbones, living in or on the sediments, a size
large enough to be seen by the unaided eye, and which can be
retained by a U.S. Standard No. 30 sieve (28 openings/inch,
0.595-mm openings). Also referred to as benthic
macroinvertebrates, infauna, or macrobenthos.

Degree to which chemicals can be taken up by organisms.

Refers to the variety and variability among living organisms and
the ecological complexes in which they occur. Diversity can be
defined as the number of different items and their relative
frequencies. For biological diversity, these items are organized
at many levels, ranging from complete ecosystems to the
biochemical structures that are the molecular basis of heredity.
Thus, the term encompasses different ecosystems, species, and
genes.

Using biomonitoring data biological surveys and other direct
measurements of resident biota in surface waters to evaluate the
biological condition or health of a place (such as a stream,
wetland, or woodlot).

Narrative or numeric expressions that describe the biological
condition (structure and function) of aquatic communities
inhabiting waters of a designated aquatic life use. Biocriteria
are based on the numbers and kinds of organisms present and are
regulatory-based biological measurements.

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.

Sampling the biota of a place (such as a stream, a woodlot, or a
wetland); use of a biological entity as a detector and its
response as a measure to determine environmental conditions.
Toxicity tests and ambient biological surveys are common
biological monitoring methods.