The Differences In Benthic Macroinvertebrate Communities When A Comparison Is Made Between Multiple Reaches With Special Attention To Man-Made Structures [Joliet Junior College]

Abstract

The use of macroinvertebrates as indicator organisms is cheap, easy, and a reliable way to determine water quality. To determine the effects on man-made structures on macroinvertebrate communities and stream quality, comparisons were made between macroinvertebrate samples from established open canopy upstream and forested downstream reaches, and adjacent reaches with man-made structures (road bridge and foot bridge). Macroinvertebrates were collected using a D-frame kicknet, following Illinois Riverwatch protocol. There was little difference in Macroinvertebrate Biotic Indices and Shannon Diversity Indices between established and adjacent reaches. However, there were significant differences between EPT/non-EPT and pollution intolerant/tolerant organisms found between all reaches, and between all paired comparisons of the established and adjacent reaches (p< 0.05), except when comparing the forested reach with the road bridge reach (EPT/non-EPT, p=0.583; pollution intolerant/tolerant, p=0.542), the forested reach and the road bridge (EPT/non-EPT, p=0.84), and the forested reach with the adjacent foot bridge reach (EPT/non-EPT, p=0.489). Noticeable differences in taxa distribution occurred between all reaches. Different samples obtained from different reaches indicated varying distribution of taxa, with the forested reach having more high quality EPT taxa and individuals, however all reaches displayed similar water quality of “fair”, with little impact from man-made structures.