Document Type

Peer-Review Article


To examine the effects of habitat and benthic substrate differences on macroinvertebrate assemblages along a single continuum, we tested three sites along a small northern Lower Michigan stream over a four-year period. Terrestrial habitat along the stream abruptly changed from a cedar forest, to an open meadow, to a hardwood forest within a 1.4 km reach. Reflecting these changes, overhead canopy coverage and in-stream woody debris were higher at the two forested sites, whereas the organic biomass of periphyton was higher at the meadow site. The meadow site also had faster stream velocity and a greater volume of coarse benthic substrate. Both temperature and dissolved oxygen were lowest at the cedar site, and there was no difference in pH or specific conductance among sites. The meadow site exhibited abrupt biological discontinuity as indicated by a decrease in the organic biomass of macroinvertebrate shredders and an increase in filtering collectors and scrapers. The stream abruptly returned to its previous condition when riparian forest canopy returned 100 m downstream at the hardwood site. All four years of the study yielded similar results. Our data indicate that abrupt changes in riparian canopy and benthic substrate can lead to similarly abrupt changes in the physicochemical and biological continuity of a small stream within a relatively short distance.

Included in

Entomology Commons



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