Land cover influence on macroinvertebrate assemblages in Marquette County, Michigan

Biological assessments are commonly used as a proxy for stream health. As such, they represent other variables which are often more difficult to measure, such as watershed land cover and nutrient availability. The purpose of this study is to identify correlations between the macroinvertebrate assemblages and watershed land cover in streams in Marquette County of Michigan’s Upper Peninsula. Three benthic samples were collected from riffle reaches of 25 streams using a Hess sampler. Samples were rinsed through a 500 µm sieve and identified to family. The Shannon-Weiner Index and the Hilsenhoff Biotic Index were calculated for each stream and showed considerable variation in both diversity and tolerance of sampled assemblages. Watershed land cover was extracted from the National Land Cover Data set. Watershed area varied from .34 to 145.89 km². All watersheds were largely dominated by forest, which comprised 61 to 100% of the watersheds. Residential, commercial, and transportation classes were negligible, together comprising a maximum of .16% of watershed area. Regressions between the macroinvertebrate indices and watershed land cover were completed to determine correlation.