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Measuring Mississippi mussels

Kelner points to a row of four Higgins' Eye mussels collected from the Mississippi River Tuesday. The Higgins' Eye mussel is a federally endangered species. Kelner is working to help rehabilitate its populations in the upper Mississippi. The corps' mussel survey this week will help determine how the future pool drawdown will affect not only the Higgins' Eye, but all mussel species.1 / 4
Dan Kelner, a biologist with the U.S. Army Corps of Engineers, looks over a bag of mussels pulled from the pool at Lock & Dam No. 3 Tuesday. The corps, working with several other state and federal agencies, is conducting a mussel survey this week and next week in preparation for a pool drawdown in the coming years. (Republican Eagle photo by Sarah Gorvin)2 / 4
U.S. Army Corps of Engineers diver Kraig Berberich enters the Mississippi River near Treasure Island Resort & Casino Tuesday. He spent about 10 minutes in the water collecting mussels using a quadrat, which allows the corps to determine how many mussels are in a given area and then estimate the mussel density of the entire pool. The corps, along with other agencies, will conduct about 300 quadrat tests in the next two weeks. (Republican Eagle photo by Sarah Gorvin)3 / 4
Sam Woboril, of the U.S. Army Corps of Engineers, dumps out a quadrat used to collect mussels Tuesday.4 / 4

The U.S. Army Corps of Engineers is conducting a mussel survey in the pool at Lock & Dam No. 3 this week and next week.

The survey is in preparation for a pool-wide drawdown, which will take place in the coming years, corps biologist Dan Kelner said. During the drawdown, the pool water level is reduced, allowing some native plants to regrow. However, the reduced water level can put native mussel populations at risk, Kelner said.

"It's very important that we have an idea of the impacts on mussels," Kelner said.

The corps, along with several other state and federal agencies, will conduct 300 quadrat tests over the next several days.

"It's very labor-intensive," Kelner said.

During these tests, divers enter the water and collect all the mussels in a pre-measured area. This test allows the team to determine the mussel density in that area, which they can then use to estimate mussel density in the entire pool.

"We can estimate how many mussels can be exposed (by the drawdown)," Kelner said.

On Tuesday, the corps team collected about 10 species of mussels, including Butterfly, Deertoe and the invasive zebra mussel. They also found several Higgins' Eye mussels, which is a federally endangered species that the corps and Kelner are helping to rehabilitate in the Upper Mississippi.

Sarah Gorvin
Sarah Gorvin has been with the Republican Eagle for two years and covers education, business and crime and courts. She graduated from the University of Minnesota-Twin Cities in 2010 with a  journalism degree.