Oysters are in many ways the restoration darlings of the Chesapeake Bay cleanup effort. Touted for multiple benefits — as edible, water-filtering moneymakers — oysters attract both enthusiasm and funding to promote their recovery.
But the popularity of oysters often overshadows the water-cleansing role of other filter feeders such as mussels. A growing group of mussel advocates think it’s high time that the bivalves share the spotlight as clean-water workhorses that can carry the message farther upstream.
Projects to propagate mussels and restore them to waterways where they once thrived are cropping up in parts of Virginia, Maryland, Delaware and Pennsylvania as researchers working on them in various states begin to join efforts. The goal is to return some of the diversity once found in these waterways — mussel by mussel — so they can filter, feed, clean and otherwise serve the local ecosystem.
In late July, the Chesapeake Bay Foundation convened a meeting in at Virginia Commonwealth University’s Rice Center on the James River, just south of Richmond, with more than two-dozen scientists and water quality advocates who are interested in seeing mussels expand their reach in the watershed. The day included a tour of a local mussel hatchery.
Joe Wood, the foundation’s Virginia scientist, sees mussels as a valuable tool for engaging new audiences in restoration work, particularly those who live far from the Bay and don’t feel connected to it.
“Mussels are a mascot they can rally around that relates to local water quality,” he said. “They’re also just really cool.”
Freshwater mussels come in all shapes and sizes, with nicknames that indicate their unique forms or textures, such as snuffbox, spectacle-case, pimple-back and pistol-grip.
Most live in rivers or streams, some others in lakes and ponds, but all rely on a current of water to provide phytoplankton and bacteria that they filter-feed from the water. Some species can live to be more than 100 years old.
They also have a complex life cycle that makes them difficult — but not impossible — to reproduce in hatcheries. Most need a fish to act as a host as they start their life: The larvae find shelter and grow in fish gills until they can navigate the waters on their own. Some mussels create lures to draw in their preferred host, and some clamp onto the fish with traplike mouths. If the fish species preferred by a certain mussel disappears, the mussel does, too.
“That’s what gets folks hooked on mussels,” said Brian Watson, a mussel biologist for the Virginia Department of Game and Inland Fisheries, at the James River meeting. “They’re highly diverse. There are species that live in streams no wider than this podium.”
Other parts of the country, such as the Tennessee River system and Delaware Bay, have seen the fruit that comes from investing in mussel propagation and research. Meanwhile, mussels have often fallen below the radar of Chesapeake Bay restoration efforts.
That may be because freshwater mussels, unlike oysters or some saltwater mussels, don’t end up on human plates. Research and restoration funding is harder to come by, even though three-quarters of freshwater mussel species are considered to be at some level of impairment. The money often comes in an off-and-on fashion from mitigation payments for environmental disasters and permit renewals, and partners in the Chesapeake Bay restoration effort community have not focused their resources on mussels. That may be changing.
Many of the mussel advocates who gathered along the James River in July first interacted with the mollusks outside of the Chesapeake Bay watershed — in the Clinch River, which rises in the southwest corner of Virginia and flows into Tennessee. The Clinch River is home to most of Virginia’s 81 mussel species, more than a third of which are endangered. The diversity of mussels found there has made the river a hotspot for research nationally.
Richard Neves, a professor emeritus at Virginia Tech University, studied mussels there for 30 years, obtaining grants to create the university’s Freshwater Mollusk Conservation Center and mentoring more than 50 other scientists. Fish biologist Rachel Mair was one of them.
Mair helps to run the Harrison Lake National Fish Hatchery, located along the James River south of Richmond, which is spawning the next generation of mussel researchers and hundreds of thousands of mussels for rivers like the James.
“If you don’t think mussels are cool, then get a snorkel and stick your head in the Clinch River,” Mair said. “If you don’t think that’s amazing, there’s no hope for you.”
The Harrison Lake facility, built in the 1930s to support recreational fisheries, now has the capacity to grow tens of millions of mussels. Over the last decade, the facility transitioned from a focus on migratory fish species such as American shad to also growing tiny glochidia, the name for larval-stage mussels, into young mollusks.
When Dominion’s Bremo Power Station renewed its water discharge permit, the hatchery got more than a half-million dollars from the deal after a threatened mussel was found to be impacted by its discharge. When DuPont had to pay $42 million to settle a case over mercury contamination of the South River, the hatchery got $4 million. The coal ash spill in the Dan River in 2014 brought in additional funds to help replenish mussel species that might have been lost.
“It’s things like that that we have to, unfortunately, rely on for the work that we do,” Watson said.
Still, Mair considers the hatchery, which employs five people, “fortunate” to be among the most well-staffed mussel facilities. And, their work is finally paying off.
The hatchery team used to release tiny mussels into portions of the James watershed and hope for the best. Now, the staff has the technology to grow them “almost indefinitely” at the facility to a large enough size that they have much better survival rates in the wild.
The center propagates the mussels by collecting female mussels that already have larvae in their gills, which the staff either extracts with a needle (to mimic a fish rubbing against it) or allows the mussel to release. Placed into tanks with their host fish, the larvae will attach to the fish before dropping off two to four weeks later to continue feeding and growing in a series of tanks. The lab is also working on in vitro fertilization for mussel species whose host fish is not known.
“We’ve come a long way,” Mair said. “In 2005, even getting a picture of the mussels we were releasing was hard, they were so small. In 2017, with some species, we’re really able to move the needle. We’re finally getting to the point where we can pick restoration sites, plan numbers, tag and go monitor them later. It’s taken 20-plus years.”
At the hatchery, in a squat building paid for by the Bremo mitigation funds, biological science technician Bryce Maynard demonstrated methods used to tag and track the progress of mussels grown here before being launched into wild waters. He flipped the switch on a laser engraver that can carve numbers into several rows of mussels at a time, leaving a burnt-hair smell in the air and marking thousands of mussels a day for future tracking.
Among the hatchery mussels are rare species such as the James spinymussel, which was once abundant in the James River upstream of Richmond but disappeared from most of its range by the late 1980s. The hatchery-raised spinymussels are marked with tags sealed in place with dental cement. The tags can be located later with a beeping detector but are costlier than other tracking methods.
Every mussel that finds its way into the watershed and survives could help filter about 10 liters of water per day, said Danielle Kreeger, senior science director at the Partnership for the Delaware Estuary, where she’s become an advocate for the potential of what she calls the #mightymussel.
“Pound for pound, freshwater mussels are not slouches,” she said, debunking myths that the slower-growing animals are not as good at filtering water as other bivalves. “To me, every mussel is precious, and we need to protect them.”
Kreeger, in the coming months, will be completing a review of studies on the ability of such bivalves to enhance water quality, which she hopes will shore up the amount of data available about mussels’ benefits.
She said the findings on how much water they filter can vary based on species, location and feed, but that it’s important to gather the right data from the outset.
Even as that data is being verified, some organizations are already working to propagate mussels in their local streams, confident that the benefits will make the effort worthwhile.
After a survey a few years ago found eight species of native freshwater mussels in the Anacostia River, the Anacostia Watershed Society started an effort to boost those numbers in the District of Columbia and Maryland. Partnering with the Harrison Lake hatchery and the Maryland Department of Natural Resources, in late summer the nonprofit installed floating baskets in the center of the river filled with mussel species called alewife floaters and Eastern pond-mussels to see how they will fare after a year in the tidal Anacostia. The group also will work with 250 students from local classrooms to raise mussels in 10-gallon tanks for learning opportunities throughout the winter.
“People don’t know anything about mussels,” said Jorge Bogantes Montero, a natural resources specialist with the Anacostia Watershed Society, who has developed his own hashtag for the project: #musselpower. “We have to educate them that we don’t have oysters here, but we do have [mussels].”
Officials from Maryland’s DNR also are working to restore Eastern elliptio mussels to portions of the Patapsco River where they once flourished, transferring them from a creek in Harford County, MD, where they are well established.
Both fresh and saltwater mussels maintain a natural presence in the Bay, too, though their numbers have dwindled in recent decades. That’s one reason why members of the Magothy River Association were thrilled to see an “explosion” of dark false mussels in the river’s creeks this summer after an influx of rain that made the water fresh enough to support those growing near the surface in floating cages and docks.
The association’s president, Paul Spadaro, said that they could almost predict the native species would have a heyday this year, after seeing a similarly rainy season foster their growth in 2004. That year, the mussels did so much to clean the water that Spadaro and his neighbors joked it had become “as clear as gin.”
A freshwater future
Clearer water is just one of the “ecosystem services” mussels provide that researchers like Delaware’s Kreeger are trying to promote. At the Virginia meeting, Kreeger laid out a vision for a robust culture of mussel propagation that could improve miles of streams — and the possibility of funding a hatchery in Pennsylvania that would provide the bivalves to both the Delaware and Chesapeake estuaries.
“To me, this is absolutely the future,” she said, noting how mussel farms in Europe are generating nutrient-reducing credits that developers can purchase. “How quickly we get there, we’ll have to see.”
Kreeger said that more research is needed to verify the scientific community’s assumptions about mussels and how different species perform in various environments. That effort could help mussel propagation become a practice that is not only good for the Bay and river water quality, but one that could be measured.
Wood, the Bay Foundation scientist, wondered whether expanding the presence of mussels could become a goal for each of the Chesapeake’s tributaries. Could states eventually get credit for the water-filtering mussel banks they’re protecting or creating? What if native mussels could be added to more stream restoration projects?
The Chesapeake Bay Program already credits states for some of the nutrient-reducing work achieved by oyster aquaculture and restoration, but it took years for a panel to collect the scientific evidence to support it.
For Wood and others, the “mussel meeting” built momentum around an issue they’d followed for years. Some said the bivalves are also doing important work as a motivator.
“I’ve become convinced,” Wood said, “that freshwater mussels can get people excited.”