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Minnesota Department of Natural Resources, Lake City, MN 55041, USAABSTRACT1. To evaluate patterns in mussel assemblages in the Upper Mississippi River (UMR), data from systematicsurveysof mussels conducted in threelarge reaches(Navigation Pools5, 6, and 18) from 2005–2007were analysed.2. Nonmetric multi-dimensional scaling analyses and permutation tests indicated that assemblages differedamong reaches. The mussel assemblage in Pool 18 was substantially different from the assemblage in Pool 5and moderately different from the assemblage in Pool 6, whereas assemblages in Pools 5 and 6 were similar.Assemblages in broadly defined, flowing aquatic habitats did not substantially differ.3. The dissimilarity of Pool 18 was primarily the result of Pool 18 having higher abundances of three Quadrulaspecies(Q.quadrula,Q.pustulosa,andQ.nodulata),andlowerabundancesofAmblemaplicataandFusconaiaflava.4. Rarefaction analyses showed that species richness and species density were higher in Pool 18 compared withthe other two pools.5. Large-scale patterns in mussel assemblages may be related to other longitudinal trends in the system includinggeomorphology, water quality, and abundances of fish species that serve as hosts for glochidial larvae.6. The results suggest that management goals and actions in the UMR may need to account for importantdifferences in mussel assemblages that occur among reaches.Published in 2012. This article is a US Government work and is in the public domain in the USA.Received 04October2011; Revised 27March 2012; Accepted 10April2012 |
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