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Multimetric Macroinvertebrate Indices for Mid-continent US Great Rivers
Citation:
ANGRADI, T. R., M. S. PEARSON, D. W. BOLGRIEN, T. M. JICHA, D. L. TAYLOR, AND B. H. HILL. Multimetric Macroinvertebrate Indices for Mid-continent US Great Rivers. JOURNAL OF THE NORTH AMERICAN BENTHOLOGICAL SOCIETY. North American Benthological Society, Lawrence, KS, 28(4):785-804, (2009).
Impact/Purpose:
To document research results.
Description:
We developed a set of great river macroinvertebrate indices of condition (GRMICs) for the mid-continent great rivers. We used a multiscale (site, reach, landscape) multimetric abiotic stressor gradient to select macroinvertebrate assemblage metrics sensitive to human disturbance and to derive reference expectations. Based on multivariate analysis of macroinvertebrate assemblages, we developed GRMICs for each of 5 reaches, the Upper Missouri River, the Lower Missouri River, the unimpounded Upper Mississippi River, the impounded Upper Mississippi River, and the Ohio River. For each reach, we developed indices for the littoral benthos and for assemblages on woody debris (snags). We created 2 versions of each index: a version including all types of metrics (e.g., autecology, diversity, composition, tolerance to pollution) and based on the absolute value (AV) of the correlation between invertebrate metrics and the stressor gradient, and a version that included no tolerance-value-based metrics (NTV). All indices included a mix of metrics unique to the reach for which it was developed. With the exception of the unimpounded Upper Mississippi River, for which we sampled few sites, we concluded that all the indices were reliable for general assessment of great-river aquatic conditions. The AV and NTV versions of the GRMIC were highly correlated (r >0.9) for both the littoral benthos and snags. The indices revealed longitudinal variation in condition on great river reaches and among-river variation in relative condition among reaches (the proportion of the river in a condition similar to the least disturbed sites for that reach). No sites near or within 100 km downriver of Kansas City, Missouri on the Missouri River or Minneapolis-St. Paul, Minnesota on the Upper Mississippi River were in least disturbed condition. About 45% of the Ohio was in least disturbed condition based on the littoral benthos compared to 25% of the Missouri River and 10% of the Upper Mississippi River. GRMICs for snags and benthos indicated that sites were in the same condition (i.e., both in least- or both in most-disturbed condition) 80% of the time.