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Invertebrate Community Index(ICI)-The following is from a paper by Dr. Steve Gordon of the Ohio State University. For the entire paper please click here.Similar
to IBI for fish, ICI is a summary measure of 10 metrics representing aquatic
macroinvertebrate community integrity and is evaluated and scored in relation to
conditions at relatively undisturbed reference sites (Ohio EPA 1989). In this
index, a site can receive a 6, 4, 2 or 0 score depending on how it compares to
the specified reference site. Scoring is very similar to IBI; here the maximum
score is 60 (10x6) and the minimum is 0 (0). Ohio EPA decided to use both fish
and macroinvertebrate indices because there is a large amount of information on
life history, tolerances and distribution and both groups have been widely used
in similar biological assessments (Ohio EPA 1987). The following is a brief
description of the metrics comprising Ohio EPA's ICI as outlined by Ohio EPA
(1987). • Total Number of Taxa - species richness and
diversity increases with warm water stream quality; inverse relationship with
drainage area • Number of Mayfly Taxa - pollution sensitive
species; greater proportion of taxa indicates higher environmental quality • Number of Caddisfly Taxa - main component in
larger, unimpacted waterways; wide range of pollution tolerances within taxa • Number of Dipteran Taxa - have wide range of
tolerances to pollution; often only organism collected under heavily polluted
conditions - greater proportion suggests lower stream quality • Percent Mayfly Composition - easily affected by
even minor disturbances; serves as measure of overall levels of stress and
disturbance • Percent Caddisfly Distribution - quickly absent
under environmental stress; serves as a measure of stream stress • Percent Tribe Tanytarsini Midge Composition -
often predominant group at minimally impacted sites; pollution tolerances are
intermediate • Percent Other Dipteran and Non-insect Composition -
includes non-insect invertebrates such as worms, isopods, snails, etc.; main
community component in poor water quality conditions - greater abundance
indicates lower environmental quality • Percent Tolerant Organisms - tolerant to toxic
and organic pollution; greater proportion of organisms indicates lower overall
environmental quality • Number of Qualitative EPT Taxa - qualitative
measure of habitat diversity and water quality; measures richness of mayfly (Ephemeroptera),
stonefly (Plecoptera) and caddisfly (Trichoptera) taxa |
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