Muscling their way back

 

By Callie Sacarelos, Communications and Marketing Coordinator

Five people wearing life jackets on a pontoon boat inspect a large wooden tray full of freshwater mussels collected from the river they are floating on. The people are smiling, wearing sunglasses, and appear to be talking to each other.

Teams from the National Park Service, Army Corps of Engineers and EcoAnalysts moved mussels out of the way of a channel improvement project in lower Pool 2 in 2018. Copyright with permission: Aaron Mcfarlane.

A consortium of researchers have been monitoring the Mississippi River at Hidden Falls Regional Park for nearly 15 years. But it wasn’t until the summer of 2021 that they finally found what they were looking for. Diving beneath the water’s murky surface in full scuba gear, they discovered several 2-year-old Higgins Eye mussels. After 22 years of collective efforts to reintroduce the endangered species to this designated essential habitat, they found proof that these mussels are finally reproducing naturally.

A hand is extended out above debris on a sand beach of the river. The hand is holding 3 freshwater mussels with wart-like bumps protruding from the shells.

On October 4 2020, the US Army Corps of Engineers began the process of lowering the Mississippi River’s water level immediately below St. Anthony Falls. During this time, researchers monitored the exposed sand, rescuing mussels by throwing them back into the river. They also did a population analysis of mussels that could be found in the area while the water was lower than normal. Copyright: Mississippi Park Connection / Callie Sacarelos.

Restoring native mussel populations is a lengthy process that often takes decades before seeing progress. Mussels artfully trick certain fish species into hosting their larvae, which briefly attach to the fish until they are ready to detach into habitat only the fish can reach. So, the first step for researchers is to discover the host fish—each mussel species has a unique pairing—and find a healthy habitat where the fish exist.

Two people stand in the shallow water of a river next to a pontoon boat. They are both wearing dive gear. One person has a snorkel mask on and is holding a netted bag full of freshwater mussels that he collected from the river.

It took researchers all across the country nearly 15 years to discover the Spectaclecase mussel’s host fish. They tested some unlikely hosts, including mudpuppies, lampreys, aquatic insects, and even other mussels, in addition to more than 100 fish species. By comparison, most host fish are discovered after testing 20-30 species. Finally, four years ago in a lab at the Minnesota DNR Center for Aquatic Mollusk Programs, mussel-propagation biologists found the answer: Mooneye fish. Unfortunately, this fish doesn’t occur north of the St. Croix Falls Dam anymore, and Spectaclecase mussels no longer exist south of Hudson, Wis.

A person in full scuba gear floats at the surface of the water holding two freshwater mussels that they found in the river. The person is smiling and is not wearing their scuba mask.

Allie Holdhusen is a Mississippi National River and Recreation Area biologist and Program Dive Officer and Dive Examiner with the park’s dive program. Copyright: National Park Service.

Allie Holdhusen, a Mississippi National River and Recreation Area biologist, and Mark Hove, a biologist from the University of Minnesota, are working with others from Macalester College and the Wisconsin DNR to track existing populations of the endangered Spectaclecase. They are part of the Mussel Coordination Team (MCT), which works closely with the Upper Mississippi River Conservation Committee composed of government agencies, universities, and consulting firms. The Mussel Coordination Team includes the U.S. Army Corps of Engineers, Mississippi National River and Recreation Area, St. Croix National Scenic Riverway, U.S. Fish and Wildlife Service, U.S. Geological Survey, U.S. Coast Guard, and the DNR from Minnesota, Wisconsin, Iowa, Illinois, and Missouri, as well as colleges and universities, and environmental consulting firms.

Currently, Allie, Mark and others from the MCT are using techniques similar to those used to restore Higgins Eye to hopefully restore Butterfly, Winged Mapleleaf, Salamander and Snuffbox mussels in the Mississippi or St. Croix rivers. The St. Croix, in comparison to the Mississippi, benefits from fewer dams, fewer alterations to the riverbed, less pollution, less sediment from urban development, and less farming chemical runoff. As a result, its fish communities are more diverse, making it an excellent habitat for mussels. The Mississippi National River and Recreation Area is also an important habitat for mussels. Water quality in this section of the river is healthier than further downstream. Also, Zebra mussels haven’t taken hold in the park like they have in other parts of the river.

Two people stand on a pontoon boat. Dozens of fresh water mussels are spread out across a table top. The people are examining the mussels. The boat is on the river with a tree shoreline in the background.

Marian Schaffer, a St. Croix National Scenic Riverway biologist, and Dan Kelner, a U.S. Army Corps of Engineers biologist, count and identify mussels in the Mississippi River for long-term endangered species reintroduction and monitoring in the national park. Copyright: National Park Service.

A person in full scuba gear floats on the surface on a river next to a pontoon boat. Another person stands on the end of the boat and is lowering a net down to the person in the water. They are searching for freshwater mussels for research purposes.

Allie Holdhusen, a Mississippi National River and Recreation Area biologist, and Mark Hove, a biologist from the University of Minnesota, conduct freshwater mussel research in the river. Copyright with permission: Dan Kelner.

“When I first heard about Zebra mussel destruction in the 1990s, I thought about switching careers because I didn’t want to spend my life conserving something that might die out like the dodo bird,” Mark said. “But as a young professional I was learning about all these rare mussel species and I wanted to help them. So I followed my heart, to make the world a better place [...] A lot of passionate people are involved in this. We need to remember that we’re connected to the river and what we do with our lives does make a difference.”

 
Callie Sacarelos