University researchers rescue mussels from dams

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Undergraduate researcher Michael Hillary measures a mussel.

Ashley Moerke

Undergraduate researcher Michael Hillary measures a mussel.

Capital News Service

LANSING – Lake Superior State University is surveying river habitats to learn how to rescue native mussels threatened by hydropower dams.

The project is funded by We Energies, which has put money into a mitigation fund – most recently $253,350 for 2022 – as part of a settlement agreement, according to the Department of Natural Resources. The fund now has about $11.9 million. 

The company is a Milwaukee-based utility that provides natural gas and electricity to customers in Michigan, Wisconsin, Illinois and Minnesota.

That agreement was negotiated while obtaining Federal Energy Regulatory Commission licenses to operate several hydropower dams on the Menominee River.

Hydropower dams can kill mussels by stranding them during water drawdowns.

The project helps We Energies and other power companies better manage their reservoirs to protect native animals that live in them, said Ashley Moerke, the lead researcher.

Hydropower and other dams often displace and destroy mussel populations, some of which are decades-old.

“For example, when they draw down the water in the reservoir to do repairs on the dam, the mussels can be stranded and die,” she said. “In some of these reservoirs, it could be tens of thousands, hundreds of thousands, of mussels that die.”

The researchers scour sites along the Menominee River, looking for mussels and learning about the kinds of places they tend to hang out in.

“Our work will help these facilities to better predict where the mussel hotspots are,” Moerke said. “Then, they can bring people in to relocate the mussels in advance of a drawdown. This way, the mussel mortality is much lower.”

Native mussels are essential components of the food web, Moerke said. 

Most live 10 to 20 years, but some live up to 50 years. They provide food to semi-aquatic mammals like muskrats and racoons, which leave the shells in piles called middens. They also provide shelter to aquatic insects.

“They’ll often be found in environments that have really soft substrate, and they’ll be the only stable surface in the area,” she said. “They act as a stable floor for other aquatic invertebrates, particularly aquatic insects. 

“Studies have shown that they’ll often harbor important species, like stonefly larvae, which are a key part of many fishes’ diets.”

Native mussels also keep lakes and rivers clean by filtering the water at high rates, she said.

Due to the extremely invasive zebra and quagga mussels, invasive species can be more familiar than the native ones. Of 40 native mussels species in Michigan, about 43% are endangered.

“Native freshwater mussels are a group of organisms that are underappreciated,” Moerke said.

“I think that the general public would call them clams. But native freshwater mussels are a specific group of bivalve shellfish with a really unique life cycle and an important role to play in the environment.”

In 2019, a team of DNR experts developed protocols to protect mussels from river construction projects. That was a huge step forward.

“Since then, we developed two new protocols that were for lake projects and then one for the drawdowns,” said Elle Gulotty, a resource analyst at the DNR’s Fisheries Division based in the Upper Peninsula. “This was the first one specific to Michigan and our resources.”

Lake Superior State’s research project, which is part of those protocols, documents native mussel hotspots and develops strategies for relocating them to avoid construction. “Our crew consists of about six undergraduate researchers,” Moerke said. “We take out a few boats and use snorkeling or bottom bucket viewers.”

Once they find a mussel, they identify it.

“We take length measurements and age the mussel as well, based on its growth rings,” said Michael Hillary, an undergraduate researcher and a crew lead. “Then we give a condition estimate on the mussel. After this, we carefully put them back.”

In addition to locating and documenting mussels, researchers study the shore to understand the types of habitats they like. That way they can better predict where to find them.

“Part of the project is understanding the relationship between the area surveyed and the species recovered,” Hillary said. “Where are the staff going to be able to maximize these recovery efforts? And what habitat should they be looking at?”

The actual relocation of mussels is tedious. Efficiency is essential to save as many as possible.

Gulotty said that as water recedes during a water drawdown, mussels are exposed and in danger of drying out or being eaten. People must collect them by hand before the water recedes, document their orientation and relocate them to a similar habitat and position.

Pollution, poaching and human interference threaten mussels. The impact of habitat destruction caused by dams and hydropower facilities is less well known.

“Hydropower operations can have very severe and acute impacts and cause lots of stress and mortality, especially to freshwater mussels,” Gulotty said. 

“Habitat fragmentation from dams is very severe and widespread across the state. There are more dams than a lot of folks realize, and fewer of them are producing power than people realize.”

Hydropower is often thought of as a more sustainable and environmentally friendly option instead of fossil fuels for producing electricity. But without careful and proper management, its facilities can have disastrous effects on the environment.

Moerke said, “I think that everyone wants to do better for the environment,” but profit-driven companies consider the environment as a “luxury” they can afford to sacrifice, she said. The mitigation fund compels them to provide some protection.

This project saves power companies money since they have to pay fines for destroying native mussels, Moerke said. If they have efficient methods of moving the mussels, it is cheaper to relocate the mussels than to deal with the fines.

Nicoline Bradford reports for Great Lakes Echo.

Michael Hillary of Lake Superior State University holds a freshwater mussel collected during a snorkeling survey

Ashley Moerke

Michael Hillary of Lake Superior State University holds a freshwater mussel collected during a snorkeling survey

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