Macroinvertebrate Community Structure of Two
Southern Michigan Trout Streams

Erik J. Bartel
School of Biology and Chemistry, Lake Superior State
University, Sault Ste. Marie, MI. 49783


	An analysis of the macroinvertebrate (aquatic insects and arthropods) community
structure of stream ecosystems can give valuable information as to the condition of the
stream in question. By examining invertebrate communities, you can tell the relative health
and quality of streams and look for any areas of concern, such as point source pollution
and habitat destruction. This is important not only to the scientist, but also to the naturalist
and concerned fisherman. The objectives of this study were to first, develop a simple
method of stream analysis that can give an indication of stream health. Then compare the
macroinvertebrate commumty of a designated trout stream, McKinzie creek, to that of a
non-designated trout stream, Pokagon creek, to look for any differences in community
structure. Finally, use this method of analysis to assess the two streams' health and quality
and to compare their community structures to those predicted by the River Continuum
Hypothesis. The two streams selected for this study, McKinzie and Pokagon creek, are
located in south western Michigan and are both first order streams (headwater streams
with no tributaries). Three sample sites were chosen for each creek and five invertebrate
samples were taken at each site. The samples were keyed to family and grouped by their
feeding guilde (collector, predator, scraper, shredder, and detritivore) in preparation for
analysis. Paired comparison T tests were preformed, showing no significant difference in
total macroinvertebrate density between the two streams. However, significant differences
were found in the densities of three ofthe five feeding guildes (scrapers, shredders, and
detritivores) between the two streams. Using Wilhm's biotic index, both streams can be
considered healthy and their invertebrate communities differed from those predicted by the
River Continuum Hypothesis.

Selected References

Huggins, D. G., Liechti, P. M., Ferrington, L. C. 1985. Guide to the Freshwater
Invertebrates of the Midwest. Kansas Biological Survey, University of Kansas.

Wilhm, S. L. 1986. Use of Biomass Units in Shannons Index. Ecology. 49 pg. 153-156.