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Macroinvertebrates serve as a major food source for
trout, and are an integral part of the normal energy and organic
material processing system in streams.
Click here for
Macroinvertebrate monitoring data.
Click here for Field
and Laboratory Methods.
Thermal Preferences of Macroinvertebrates
(Galli, 1990)
Many aquatic insects (esp. mayflies) require a fluctuating diurnal
temperature regime
Temperatures > 17 C (63F) exceed the optimum for many stoneflies,
mayflies, and caddis.
Picture source:
http://www.epa.gov/adopt/patch/html/critters.html
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Temperatures > 21 C (70F) can severely stress
most coldwater macroinvertebrates
Upper Limiting Temperatures: |
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Stoneflies: 13 – 20 C |
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Mayflies: 12 - < 25 C |
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Caddisflies: 20 – 35 C |
Because of temperature regime alteration, temperature-sensitive or
thermally-cued macroinvertebrates are often reduced or eliminated,
leaving only types with broad tolerance ranges.
Clarke's Bugs
Clarke
Garry is a professor of biology at the University of
Wisconsin - River Falls. These articles are the
first few of what we hope will become a regular
series of articles on entomology and ecology from
Dr. Garry. For more info see
Clarke Garry's site, The links below will
re-direct you to the Kiap-TU-Wish website and will
open in a new window. Please disable your pop-up
blocker (if you have one) or right click the link
and click "open in new window".
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There's a whole
world of life in rivers and streams. Living alongside fish,
amphibians, reptiles, and wildlife are macroinvertebrates—creatures
that are large (macro) enough to be seen with the naked eye, and
that lack a backbone (invertebrate). Aquatic insects, clams,
snails, crayfish, worms and leeches are all macroinvertebrates.
Some, like snails, live their whole lives in the water; others,
like dragonflies, leave the water as adults to feed and
reproduce. In streams, most macroinvertebrates live under or
attached to submerged rocks, logs, and plants. Like all living
things, they need oxygen to breathe, water of the right
temperature to thrive and reproduce in, suitable habitat, and
the right kind of food. When these requirements aren't met,
these creatures will sicken and die.
Scientists and trained volunteers study macroinvertebrates to
learn more about stream quality. The basic principle behind the
study of macroinvertebrates is that some are more sensitive to
pollution than others, so if you find lots of macroinvertebrates
that can't tolerate pollution, you've found a pretty clean
stream. On the other hand, if you find only macroinvertebrates
that can live in polluted conditions, your stream may have a
problem. Below are a few examples of macroinvertebrates that
live in clean streams.
Source:
http://www.epa.gov/adopt/
patch/html/critters.html
Used with permission |
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