HARRISBURG, Pa. — As a new report details the importance of restoring declining populations of freshwater mussels within the Chesapeake Bay watershed, multiple programs in Pennsylvania are working to do just that.
The report “Incorporating Freshwater Mussels into the Chesapeake Bay Restoration Efforts,” comes from a workgroup of experts under the Environmental Protection Agency’s (EPA) Chesapeake Bay Program. It lays the groundwork for expanding mussel restoration in the Bay watershed with a growing coalition of advocates and scientists across the region.
“Freshwater mussels really are unsung heroes in Chesapeake rivers and streams. But as their populations plummet, I’m afraid we could lose some mussel species before we fully understand their benefits,” said Chesapeake Bay Foundation (CBF) Virginia Senior Scientist Dr. Joseph Wood, who is the lead author of the report.
More than half of all freshwater mussel species are now facing extinction. About 25 species live in the freshwater rivers and streams that flow into the Chesapeake Bay.
“Like forests alongside streams, native freshwater mussels in rivers and streams help restore and protect water quality in Pennsylvania’s rivers and streams,” said Harry Campbell, CBF’s Science Policy and Advocacy Director in Pennsylvania. “They do this by filtering out things that act as pollutants in the water and are a food source to them.”
A single mussel can filter up to 15 gallons of water per day, which can prevent pollutants such as nitrogen from flowing downstream, leading to clearer and cleaner water. Mussel beds create habitat for small aquatic creatures, which in turn become food for fish.
“A lot of people call them the ‘livers of our rivers’ because they filter things that are harmful to humans, like toxins and heavy metals out of the water that passes over them,” added Dr. Heather Galbraith, a Pennsylvania Fish & Boat Commission (PFBC) Water Planning Biologist who contributed to the report.
For a Commonwealth where more than 25,000 miles of rivers and streams are harmed by pollution, and that provides half of the freshwater to the Chesapeake Bay, protecting and restoring freshwater mussels have important implications for clean water.
With multiple efforts underway in Pennsylvania, it could take years before significant populations of freshwater mussels are in place to benefit local waters in the Susquehanna River Basin and downstream to the Bay.
The Mussels for Clean Water Initiative (MuCWI), coordinated by the Partnership for the Delaware Estuary (PDE), aims to restore freshwater mussels to streams, rivers, and lakes in the upper mid-Atlantic region, particularly the Delaware and Susquehanna River Basins.
Under MuCWI, ground will be broken in 2022 for a central hatchery to be built in southwest Philadelphia. It is supported by an investment from the Pennsylvania Infrastructure Investment Authority.
Up to 500,000 baby mussels will eventually be produced annually at the Philadelphia hatchery. The offspring will be used to support diverse recovery efforts in streams, rivers and lakes in the Delaware and Chesapeake watersheds in Pennsylvania, as well as adjoining states.
“The goal of MuCWI is to restore functional mussel beds containing natural assemblages of both common and rare species,” said Dr. Danielle Kreeger, Science Director for the PDE. “By our estimate, this new PA-based effort is the first of its kind to focus on the less rare species that do the bulk of the water filtering. But we will of course also do what we can to help sustain the rare species too.”
According to the Western Pennsylvania Conservancy, 10 of Pennsylvania’s freshwater mussel species are considered endangered, and another 13 have not been observed for decades. The conservancy is working on a number of projects to establish the distribution of rare mussel species in Pennsylvania – in the Delaware, Potomac, Susquehanna, and Ohio basins.
At the Union City Hatchery in Erie County, the PFBC converted a facility to raise mussels in 2019. Last July, the Commission stocked 200 mussels into Dunkard Creek in Greene County.
The PFBC effort is funded by a settlement after a massive fish-kill at Dunkard Creek in 2009, and the focus is on restocking Union City’s mussels into that creek. The Commission hopes to stock another 2,000-3,000 mussels there in 2022.
Biologists caution that re-introducing freshwater mussels is not the silver bullet solution to pollution.
“If all of our environmental problems can be solved by just dumping in buckets of mussels, we would have figured that out a long time ago,” Dr. Galbraith said.
“We found that mussel restoration would be one more arrow in your quiver, but you cannot do mussel restoration unless you continue to double down on existing best management practices like buffers and cover crops,” Dr. Danielle Kreeger added.
Establishing proper habitat before introducing mussels is key to their survival.
“What mussels don’t like is unstable or scoured bottom habitat,” Dr. Kreeger said. “The problem is that with increasing bouts of heavy rainfall and impervious surfaces due to development, we get flash flooding that scours the streambed every time it rains hard. Mussels need a safe place to burrow into, so they don’t get washed out or buried by fine sediments every time it rains.”
“When combined with proven practices like forested riparian buffers, rain gardens, cover crops, and other techniques that keep soils and nutrients on the land instead of in the water, mussels represent a promising new tool to further efforts to restore the Commonwealth’s rivers and streams,” Campbell added.
The new report estimates that mussel populations in the Chesapeake Bay watershed have likely fallen by 90 percent since European colonists arrived in the 1600s.
“Just like oysters in the 1980s, freshwater mussels are on the brink of catastrophe,” said Wood. “The progress we’ve made with oysters should inspire hope for what could be done with mussels, but progress requires investments. To turn things around, new funding is needed for clean water, restored habitat and protecting and rehabilitating mussel populations.”
–BJ Small, Chesapeake Bay Foundation