Tag Archives: Rachel Mair

Restoring Rivers with a Little Mussel Power

Freshwater mussels are one of nature’s greatest natural filtration systems. A healthy bed of mussels, in a reach of river just 2 football fields long, can filter over half a million gallons of water every day.

Many cities use rivers for their drinking water. And the river water must be treated to remove fine sediments and harmful bacteria and algae we don’t want in our water. It costs slightly more than $2/1000 gallons to deliver clean water to our homes, with treatment accounting for 15% of those costs (EPA). In 2005, Cincinnati, OH treated 136 million gallons per day; that’s over $17 million per year!

Rivers where freshwater mussel beds are intact could cost less to treat because mussels have been doing their job. “Filtering and recycling nutrients within food webs is an important job and these ecological engineers do it for free” says Dr. Danielle Kreeger, Science Director for the Partnership for the Delaware Estuary.

Because mussels don’t move much (and certainly not quickly!), they are vulnerable to chronic pollution in the water and changes in habitat, including sediment buildup. Additionally, as rivers have been dammed and altered fish are harder to find above some barriers,

making mussel reproduction much harder. Over 70% of the 300 species of mussels in North America have been in decline for decades. Since the Clean Water Act, however, water quality has improved in many of our rivers. And through several other federal programs, we are restoring river habitats and removing barriers to fish passage.

The U.S. Fish and Wildlife Service began investing in freshwater mussel culture (and stocking) of freshwater mussels for recovering endangered species back in the late 1990s. We also have been collaborating with State agencies to culture species that formerly comprised a large portion of the biomass in rivers. Those methods are now helping restore these ecological engineers and recover endangered species.

In 2007, we partnered with the Virginia Department of Game and Inland Fisheries (DGIF) to restore freshwater mussels in Atlantic slope rivers of Virginia. The Virginia Fisheries and Aquatic Wildlife Center (VFAWC) at the Harrison Lake National Fish Hatchery (NFH) has been raising more than 12 different species, thanks in part to the work of biologist Rachel Mair, hatchery manager Michael Odom and Brian Watson from Virginia DGIF.

Rachel Mair, Harrison Lake NFH freshwater mussels are reared in floating baskets in these productive ponds. Credit: USFWS

The partnership has released over 185,000 mussels into Virginia rivers, including the Rappahannock, Appomattox, Mattaoponi, Pamunkey, Meherrin and Nottoway. They also are helping the Partnership for the Delaware Estuary restore mussels (and rivers) in the Delaware River basin.

The work hasn’t stopped there. The partnership is currently raising many at-risk mussel species including:

  • Endangered James spinymussel: 1,000 being raised and PIT tagged for stocking in the James River this fall
  • Atlantic pigtoe: petitioned for listing
  • Green floater: petitioned for listing
  • Brook floater: petitioned for listing
  • Yellow lampmussel
  • Triangle floater
  • Notched rainbow

Indeed, the VFAWC will be raising many of the above species to restore ecosystem health back to the Dan River, Roanoke River basin. The Dan is a life source for residents in North Carolina and Virginia. The river provides drinking water, is used for recreational and subsistence fishing, for canoeing and kayaking, to irrigate crops and provide water to cattle. In 2014, however, a coal ash spill occurred near Eden, NC, that extended 70 miles downstream. The hatchery will be raising and stocking mussels, a critical step to restoring both species and ecosystem services mussels provide.

“If the causes for harm and degradation are removed, the environment can heal as long as the seeds for getting started are still there”, says Brian Watson. He adds “In the case of freshwater mussels with a complicated life cycle, it could take decades for a bed to rebuild itself. That’s why they need a little assistance to jump start the process and boost their numbers.”

Elyssa Mills, James River Association and Hanna Walker (right), student stock mussels at Presquile NWR. Credit: CBrame, USFWS

Lucky for us, we have dedicated biologists with the Service and the Virginia DGIF developing methods for restoring rivers using a little mussel power.

Virginia Department of Game and Inland Fisheries and Harrison Lake National Fish Hatchery staff support the Virginia Fisheries and Aquatic Wildlife Center. Credit: Gatenby, USFWS


Mussels making moves for water quality

Beneath the surface of the water, embedded in the bottom of rivers and estuaries lie thousands of little suspension-feeding bivalves called freshwater mussels. They are a fascinating group, with a unique role in our freshwater ecosystems. The presence of mussels benefits all the life around them, and in return, they receive a little help from their fishy friends.

Freshwater mussel diversity, J. Butler/USFWS

Mussels begin their life in an unusual fashion with males releasing gametes into the river to an awaiting female. The female captures these through normal filter-feeding; her eggs are then fertilized in special “brood chambers” in the gills called marsupia. Once fertilized, a female mussel will carry her developing larvae for several months. For the larvae to complete metamorphosis, however, the female mussel must attract an unsuspecting fishy host. With her flashy mantle tissue, she puts on a show, and the performances are impeccable!

Like an improvisational dancer, disguised as some delicious food item – black fly larvae or other insect larvae, a small minnow, or perhaps a crayfish-

undulating and waving in the water, she captivates her audience.

Or like an expert fly fisherman, she casts out a delicious lure. (Barnhart, M. C.  2008. Unio Gallery)

When the fish approaches, she expels her parasitic larvae at the unsuspecting fish, where they get lodged in the fish’s gills. The young mussels drop to the river bottom after a few weeks, with no harm to the fish. This is where the real magic happens!

There’s more to these fish-charming bivalves than their underwater showmanship, they also take out the trash, clean the water and stabilize the foundation of the community for all the other aquatic critters living near them. Indeed, freshwater mussels play an important role in engineering the ecosystem. Like cobbles and rocks, they help stabilize the river bottom during high flows. And they help aerate sediments with their movements. But these shells aren’t just pretty rocks; they’ve got gills and guts! By recycling nutrients into the food web they provide food for other aquatic life, while also creating habitat.

Freshwater mussels are also one of nature’s greatest natural filtration systems. “A single freshwater mussel typically filters 5 to 10 gallons of water per day, 365 days a year” reports Dr. Danielle Kreeger, Science Director for the Partnership for the Delaware Estuary. She added, “Since healthy mussel beds can contain tens of thousands of mussels per acre, they function like natural water treatment plants that help keep the water clear and remove many types of pollutants.” Imagine 10,000 mussels filtering 10,000 gallons of water a day. Now imagine all that happening over 300 miles in a river such as the Allegheny or the Susquehanna or the James. 

By feeding on microscopic particles that cause turbidity, freshwater mussels remove vast quantities of algae, bacteria, nitrogen, phosphorus and other chemical compounds in the river. And what they don’t use is repackaged into little organic baskets of food for organisms like aquatic insects, which are valuable food items for fish, or aquatic fungi that facilitate decomposition processes in the river. Put it all together, and where there are mussels, you find more aquatic insects and more fish and better water quality. 

Tangerine and gilt darters near Dromedary pearl mussel (Dromus dromas) in a bed of other mussel species. Credit: Rachel Mair/USFWS