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Steps in Developing a Bioassessment and Biocriteria Program
Metric Evaluation and
Index Development
Potential metrics which have ecological relevance are identified and
tested in this step. These measures should reflect biological properties
which are shown to be sensitive to environmental impairment such as
richness, diversity and dominance indexes, biomass and mean individual
size measurements, trophic shifts, health indexes, abundance proportions
of taxonomic groups, and the presence or dominance of tolerant (opportunistic)
and sensitive species. Metrics are then evaluated for their ability
to differentiate between impaired and minimally impaired sites. Values
from various scales of measurements are transformed to scores, which
are normally incorporated into an index, such as the Index
of Biotic Integrity (IBI). Metrics may also be used individually
as indicators of biological condition in the overall assessment, after
they have been reevaluated using the new data set.
Read more information on metric evaluation and index development for
Streams and Small Rivers, Lakes,
and Estuaries.
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