Macroinvertebrate community structure and its seasonal variation in the Upper Mississippi River, USA: a case study

Abstract

We surveyed benthic macroinvertebrates in the Upper Mississippi River near Minneapolis and St. Paul, Minnesota, USA (1350–1380 river km) using Hester-Dendy multiplate samplers as artificial substrates. Two study sites were sampled in multiple seasons at two depths over two years during the period from 2007 to 2009. We examined the patterns of seven community metrics summarizing richness levels and/or relative abundances of major community subsets. Richness metrics were driven by rare (occurring in less than 10% of the samples) taxa but overall densities and relative abundances of major groups reflected the presence of a few dominant taxa. Using analysis of variance, community metrics differed between study years or sampling depths only sporadically, but consistently differed among survey periods. Non-metric multidimensional scaling analysis indicated samples primarily clustered by survey period (within years) and sampling depth at one of our sites and by study year and survey period at the other site. A relatively small number of taxa were consistently abundant in our study, many of which have been reported as community dominants in other large river studies. Annual variability in assemblage composition generally reflected atypically high numbers of one or more of these persistent dominants, and was likely related to differences in hydrological conditions between years. Seasonal variability, however, was relatively consistent between years at both study sites.

Keywords:

• benthic macroinvertebrates
• Upper Mississippi River
• bioassessment
• Hester-Dendy samplers
• non-metric multidimensional scaling

Acknowledgments

All information that was not publically available is acknowledged. We are very grateful to Brad Giese, Brian Schmidt, Seth Carlson, and Luke Kusilek for assistance in the field, and to Len Ferrington and his students for help with sample processing and taxonomic identifications at RIV. We also thank Ryan Argo for providing data from the Ohio River. Jan Battle provided invaluable guidance with data analysis. Comments by Ted Angradi, Jan Battle, Todd Hubbard, Casey Scott, and two anonymous reviewers greatly improved the manuscript. We also thank Jeff Barrington, Jim Bodensteiner and Dan Orr for their support of this project. The research was supported by grants from Xcel Energy.