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At a small boat ramp off the Allegheny River near Parker City, Mikayla Bayto is face down in knee-deep water, swiping her hands along the riverbed.
When Bayto, an aquatic biologist with the state Department of Environmental Protection, finds a small seam along what appears to be rock, it’s a telltale sign that she’s struck metaphorical gold she’s been looking for. She pulls it from the ground and hoists it up to get a better look.
“Clava?” she asks Rick Spear, a DEP aquatic biologist supervisor who’s monitoring from the riverside. He confirms. It is a Pleurobema clava, or clubshell mussel, a federally and state endangered species, found after just 15 minutes in the water.
Southwestern Pennsylvania is seeing a surprising number of freshwater mussel species return to waterways, experts found after concerted efforts to improve habitat and reintroduce declining species. Human activity — including pollution and sedimentation — eroded water quality and mussel population. Mussels are a sign of good water and ecosystem health.
And in the Ohio River, a survey for the Allegheny County Sanitary Authority expected to only turn up one mussel species found a record 35 mussels across 10 species in the Ohio River’s Emsworth Pool. The area sits between Brunot Island and the McKees Rocks Bridge, near ALCOSAN’s facility, Marshall-Shadeland and Stowe Township.
It’s the highest number of species found in that location since it was first surveyed around 1904, according to a review by the Fish and Boat Commission.
“This was pleasantly surprising to find this,” said Shawn McWilliams, an ALCOSAN project engineer. “No one expected it, and I think it's a win for the region for water quality.”
Normandeau Associates, a consulting firm and ALCOSAN contractor, conducted the survey to ensure mussels wouldn’t be disturbed by construction for ALCOSAN’s Clean Water Plan, a long-term project to reduce sewage overflow into the water, in part by building an underground tunnel system.
None of the mussel species found are endangered.
Mussels are particularly sensitive to water quality, so a cleaner river system is likely to attract more mussels, said Nevin Welte, a non-game biologist and malacologist, or mollusk scientist, with the state Fish and Boat Commission.
And in turn, mussels are a boon to the ecosystem. The average adult mussel filters 10 gallons of water a day and cycles nutrients in the water, earning them the name “livers of the rivers.”
They also play a vital role in the food chain, and their shells provide habitat for the larvae of caddisfly and other small creatures. In one of the dead shells Bayto pulled from the water, several fingernail-sized snails had made a home.
The mussels will be relocated to a nearby area where they won’t be affected by construction.
Bayto, Spear, and others from the DEP regularly survey waters across Western Pennsylvania to check mussel population and health, and lately, they’ve been getting good news.
But it’s hard to make wide generalizations about mussel population or species recovering based on individual surveys, said Joe Snavely, lead malacologist and senior principal scientist for Normandeau Associates.
“There are certainly populations of mussels and species that are in decline, that's an indisputable fact,” Snavely said. “It's hard to say in one fashion or another, at a broad scale, what freshwater mussel populations are doing, because some watersheds are doing very, very well, some watersheds are doing very poorly, and other watersheds are recovering.”
Mussels have taken one of the hardest hits from extinction of all animal groups, Spear said. Pennsylvania is no exception. Of its 67 freshwater mussel species, 12 are considered endangered or threatened at the state or federal level. Another 11 have not been observed in state waterways for around a century, according to Welte.
The ALCOSAN study is a positive sign, Welte said.
“In the Ohio [River] currently, there's 22 living species of mussels. But historically, it was the most diverse river in the entire state, and it had 53 species,” Welte said. "What we're seeing, as far as the trend goes, is an increase in the number of species, maybe not necessarily the numbers of mussels, but the diversity that we thought we had lost seems to be coming back.”
In July, the state Fish and Boat Commission found an elephant ear mussel in the Allegheny River. That species hasn’t been documented in Pennsylvania in over a century.
The resurgence of some mussel species can be attributed to a few factors: more surveys, better water quality, and a nearly 10-year effort to stock the rivers with mussels raised by state agencies.
The state DEP launched a program to raise and stock mussels in 2016. Since then, the DEP put almost 40,000 mussels in Pennsylvanian waters, including the Ohio, Allegheny, Clarion, Kiskiminetas, and Beaver rivers and Dunkard Creek, which lost tens of thousands of fish and mussels in 2009 after a toxic algae bloom.
The program has been funded by $300,000 in mitigation funds given to the DEP by sand and gravel dredging companies. Funding for the program ends this December. After that, the DEP will no longer raise and stock the nine species, including the state endangered round hickorynut, pistolgrip, and salamander mussels.
The state Fish and Boat Commission is also raising and releasing eight species of mussels. Currently, the Fish and Boat Commission is also working to propagate the clubshell, northern riffleshell, and salamander mussels, for a total of 11 species.
But propagating the species is no easy task. Mussels boast a peculiar lifecycle that can last over a century: the parasitic larvae attach to gills and fins of specific host fish or salamanders to grow, detaching when they hit the juvenile stage. Then, their lives as tiny filters begin.
The logistics of it, such as finding out what host fish to use at the hatchery or what temperature to keep them at, proves a challenge.
“It's maddening given how imperiled this resource is, how difficult they are to raise, and how much we still don't know,” Welte said. “It's a race against time, really, to get this information and to do the best that we can before it's kind of too late.”
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