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Upper Midwest Environmental Sciences Center

Native Mussels

Comparison of Native Mussel Assemblages Among Three Reaches of the Upper Mississippi River

Quadrula pustulosa mussel (photo by Cummings and Mayer)In the past century about 20 mussel species have become extinct from the Upper Mississippi River (UMR) basin, and at least 28 species are state or federally listed.  The species composition appears to have changed considerably from pre-European settlement times toward communities dominated by mussels that are tolerant of pollution and can utilize many different types of habitats.  River managers lack scientific information to confirm these observations.  For this study, scientists evaluated patterns in species composition from systematic surveys of mussels that were conducted in three reaches (Navigation Pools 5, 6, and 18) of the UMR during 2005-2007.

Comparison of three reachesHow do the mussel communities compare between different areas of the River?

  • Pools 5 and 6 have very similar community structure to each other, but Pool 18 has a very different community.

  • Species richness and species density was higher in Pool 18 compared to Pools 5 and 6. 

  • Across all three reaches, four species dominated recent mussel surveys, including threeridge (Amblema plicata), threehorn wartyback (Obliquaria reflexa), pimpleback (Quadrula pustulosa), and mapleleaf (Quadrula quadrula).

  • The mussel community in Pool 18 contained higher abundances of three Quadrula species (Q. quadrula, mapleleaf; Q. pustulosa, pimpleback; and Q. nodulata, wartyback) and lower abundances of threeridge (A. plicata) and Wabash pigtoe (Fusconaia flava) compared to Pools 5 and 6.

  • Longitudinal patterns in the species composition of native mussels might be partly explained by patterns in the distribution of fishes that are used as hosts for mussel larvae.  For example, higher abundances of catfishes in Pool 18 could affect relative abundance of mussel species including the three dominant Quadrula species in Pool 18, because they strongly depend on catfish hosts for their larvae.

 

Number of Freshwater Mussel SpeciesHave the mussel communities changed over time?

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