Analysis of Benthis Macroinvertebrate Communitites in the Minnesota River Watershed

Biological assessment of the Minnesota River Basin was performed partly through the analysis of benthic macroinvertebrate communities. The study sites included mainstem, major and minor tributaries within the watershed. The communities were sampled using Hester-Dendy, kick-net and hand picking techniques. Once the community compositions were sorted they were analyzed using a series of metrics. These metrics included; Richness, Diversity Index, Equitability Index, Ratio of Scraper and Filtering Collector Functional Feeding Groups, Macroinvertebrate Biotic Index, Invertebrate Community Index, Percent Tanytarsini Midges, Percent Other Dipterans and Non-Insects, Percent Tolerant Organisms and Qualitative EPT. These tests revealed that the small streams tested were all severely polluted (according to the Macroinvertebrate Biotic Index). Generally the most abundant macroinvertebrates were the caddisflies, mayflies and midges. Similar results were found when the mainstem sites were analyzed. Again, the indexes results indicated moderately to severely impacted.