Fat mussels are happy, healthy mussels says geology professor Kelly MacGregor. Why would we care about the physical state of a modest little creature that resembles a rock? Because their health reflects the health of our rivers.

For eight weeks this summer, MacGregor, four students, and Dan Hornbach, professor of biology and environmental studies, are measuring the amount of glycogen, or fat, in mussel tissue. They are using the Snake River in Minnesota as their reference site because that river is nearly pristine, says Hornbach, and has a rich diversity of mussels. Later in the month they will gather data from the Chippewa, Cottonwood, and Le Sueur Rivers, which have high levels of pollution.

On this particular day, the research crew drove an hour and a half to the Snake, where they suited up in wetsuits, weights, and heavy boots. Joining the mussels in their watery world, they brought in large nets to corral them into one location.

Unfortunately, the group didn’t find much—the previous day’s heavy rainfall had raised the water level and brought an unusual amount of sediment to the river, making it difficult to find any mussels.

This is the crux of the research. The group is researching the effect of pollution on the health of Minnesota’s rivers. Much of the sediment that goes into the waterways carries with it nitrogen and phosphorus, some of that due to changing agricultural practices. “There’s been a huge decline in the last 100 years in the mussel groups in [the rivers],” says Hornbach. “We are trying to understand if that’s due to sediment or to some other factors.”

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative‐Citizen Commission on Minnesota Resources (LCCMR). Supported by a three-year grant, Macalester is collaborating with the University of Minnesota to find some answers. This research continues work done 16 years ago by Minnesota’s Department of Natural Resources. “We are using the same methods,” says Hornbach, “so that we can compare our results with theirs.”

“Our hope,” says MacGregor, “is that we can ultimately help the state of Minnesota make some decisions about what’s going on and how we might change what we are doing to the landscape.”

The students participating in the research program are Molly Guiney ‘16 (geology), Maya Agata ‘16 (biology), Brooke Hunter ‘17 (geology), and Clara Friedman ’16 (biology).

July 20 2015

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