RE: NANFA-- F W invertebrates as water quality indicators

Hoover, Jan J WES (HOOVERJ_at_wes.army.mil)
Fri, 10 Dec 1999 08:30:04 -0600

<< I imagine the fishes are the last to suffer from most water quality
problems. Fortunately state and federal EPAs use invertebrate populations.
Certain mayflies, dobsonflies, etc are indicators of water quality. Also,
a
wide diversity of species and genera, as opposed to dominance by a few,
indicate system health.>>

<I was aware that certain insect larva were environmentally sensitive
however
I would have thought that fish, being more complex organisms, would be
affected first.>

Taxa respond at different time scales and in variable ways to water quality
(WQ) problems. Simple, short-lived organisms, like protozoans or diatoms,
thrive-or-die and so provide good short-term assessment of WQ. More
complex, longer-lived organisms, like aquatic insects, provide longer-term
assessment of water quality since they have greater ranges of behavioral and
physiological resistance. Fish communities consist of species with a wide
range of environmental tolerances and life histories. Consequently fish
provide short-term assessments of WQ, based on presence of sensitive or
intolerant species, and they provide longterm assessment, based on size
structure of individual species, trophic structure of the community, missing
species, etc.

My impression is that protozoans and diatoms were used earliest for WQ
studies (pre-1960's)and that those groups were later eclipsed by aquatic
invertebrates (post-1960's) which were easier to sample,identify,
characterize with respect to environmental tolerances (also,its easier to
relate to organisms with heads). Fishes were not popularized until the
early 1980's with the development of an assessment technique called the
Index of Biotic Integrity by James Karr. This always seemed odd to me since
fishes are perhaps the easiest and best-known of the aquatic groups and
certainly the easiest to identify to species with any confidence.


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