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Upper Midwest Environmental Sciences Center

Native Mussels

Population Assessment and Potential Functional Roles of Native Mussels in the Upper Mississippi River

Resource managers on the Upper Mississippi River need information about the status, distribution, and functional roles of native mussel populations in order to protect and restore aquatic habitats and enhance biodiversity. This project provided information to managers in the following areas:  

How many mussels are there?

Mussel population Pool 5 Pool 6 Pool 18
Total density (no/m2) 4.3 ± 0.8 2.9 ± 0.7 4.5 ± 0.9
Population estimate (millions) 190 ± 37 61 ± 15 212 ± 43
Percent of population as juveniles  45% 40% 62%
Number of species as juveniles 16 of 16
14 of 16
20 of 23

How healthy are mussel populations?

Where are mussels found?

What is their potential functional role?

  • As relatively immobile filter-feeders, mussels can remove large amounts of particles from the water column and transfer these nutrients and energy into other organisms that reside near the river bottom. In addition, large concentrations of mussels can stabilize river substrates.
  • Based on their filtration rate and density, we have evidence of the importance of native mussels in particle dynamics in the Upper Mississippi River.

  • During high river flows the mussel populations in these reaches can filter about 1% of the water volume and during low flows mussels can filter about 12%.

  • Across the 480 km reach (Pool 5 to Pool 18) the total water filtration by mussels is about 75 times that of the water filtration performed at the Minneapolis-St Paul, Minnesota metropolitan wastewater treatment plant, one of the largest in the United States.

Mussel filtration

Functional Role of Unionids-graphic cycle.png

Impact of UMESC Science

  • The results of this study suggest that native mussels play an integral role in this ecosystem by sequestering large volumes of suspended materials that can be used by other benthic organisms.

  • Managers now have critical data on population size, distribution, and relative health—these data are being used to guide habitat restoration activities to benefit native mussel populations in large rivers.



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