Putting some ââ¬Ëmussel' into it By CHARLES GARRATT • Staff writer
MILLBORO - On a seafood buffet, 56 small mussels wouldn't even be a meal, but to scientists trying to preserve the freshwater mussels of Virginia, the 56 James spinymussels found last week in Mill Creek are a bonanza.
Saturday biologist and technicians from the Virginia Department of Game and Inland Fisheries and the U.S. Fish and Wildlife Service sponsored a field day at Camp Accovac for families to participate in a rare natural science learning opportunity.
In addition to fun activities, children were able to give hands-on help in the process of assisting the spinymussel to propagate in Mill Creek.
Biologists found the James spinymussel in Mill Creek almost by chance a couple of years ago said Brian Watson, DGIF Malacologist. A team coming to survey mussels in the Cowpasture River decided to stop and take a quick look at Mill Creek and found the first James spinymussels.
Last year, biologists from DGIF and USFWS conducted a full survey of Mill Creek and found 50 James spinymussels, said Watson. This year, the survey took place before heavy rains muddied the creek Friday night, and 56 mussels were located. Of those, only eight had been tagged the previous year.
"The diversity of freshwater mussels in the United States is unmatched by any other place on Earth," said DGIF wildlife biologist Mike Pinter in the booklet "Regaining Our Freshwater Mussel Heritage." The booklet along with posters, video tapes, coloring books and other educational material was made available Saturday.
Pinter points out 70 percent of the mussel fauna in the U.S. are in peril and more than 7 percent are already extinct.
The mussels in Mill Creek are equally at risk, Watson said. Biologists found six species in the creek and two of those, one-third of the total, are listed at risk.
The James spinymussel is both federally and state listed as endangered. The Atlantic pigtoe is listed as state threatened, according to Watson.
Mussels have a complex reproductive process that relies on a good deal of luck, according to Rachel Mair from the USFWS Fish Hatchery in White Sulfur Springs, W.Va. The fewer mussels there are in a particular body of water, the lower the chances for successful reproduction, she said.
The event Saturday was planned as both an educational experience and as a way to help the James spinymussel increase its population in Mill Creek - one of only three viable populations of the mussel left.
Adult mussels live mostly buried in the gravel at the bottom of the stream. When they begin to reproduce, the mussels do not move around to find mates, said Mair. Instead, the male releases sperm into the water which the female mussel must then capture as it floats by.
After the mussel eggs are fertilized, the tiny mussels develop into a larval stage, called Glochidia, in the gills of the mother mussel. Then chance comes into play again, said Mair, and this is the stage where kids and biologists lent a helping hand on Saturday.
The tiny Glochidia must find and attach to the gills of a particular species of fish, where they live for a few weeks. The odds aren't good in a clear stream full of fish and mussels. With few mussels to reproduce in Mill Creek, the Glochidia that are released need some help finding a fish host.
Saturday, Mair, USFWS biologist Mathew Patterson and DGIF intern Melanie Stine donned waders and headed into the creek with a seine to catch fish. Rains Friday night swelled the creek to a muddy torrent. Mair took a dip up to her neck.
After some sloshing and slipping, the threesome returned to the work area with a cooler full of water and a few fish, followed by adults and nearly a dozen children.
Common shiners were removed from the captured fish and placed in an aerated tank. The remaining fish became an aquatic petting zoo for a short time before being returned to the creek.
Biologists added Glochidia collected from mussels in the creek on Friday to the tank and waited for the fish and Glochidia to get acquainted. The James spinymussel uses a little trick to catch a fish, Mair pointed out. Multiple Glochidia are contained in a membrane that looks like something a hungry shiner would like to eat, she said.
But when the shiner eats the little Glochidia, it realizes they aren't food and spits them back out, breaking the membrane right at the front of the fish where the little mussels can hitch a ride in the gills, said Mair.
The little mussels develop organs for the couple of weeks they are parasitic on the fish, and then drop off to being life as adult mussels on the stream bottom. The fish is not normally harmed by hosting the mussel, said Mair.
While the mussels and fish were doing their little dance in the tank, the children had fun exploring the creek, painting mussel shells and petting fish. Children and adults who wandered up the hill found a delicious buffet of fruit, coleslaw, sliced roast beef and cheeses provided by the Gristmill in Warm Springs.
Once enough mussels had found a fish, the biologist loaded up the cooler of water and headed back to the creek in a parade of kids and adults. At the creek side, children took turns dipping a fish from the cooler, and with a bit of direction from Patterson, returning it to the stream.
Preserving the native mussels of Virginia involves not only a matter of trying to increase populations of rare mussels. Alien mussel species like the zebra mussel also threaten to invade Virginia waters, said Watson.
Watson headed up the project to eradicate the only population of zebra mussels found to date in Virginia. The zebra mussels were found in an old quarry in Northern Virginia popular with divers, said Watson.
The successful eradication project cost $365,000, he said. However, if the pesky mussel had escaped into the waters down stream, the cost of control at each power and water plant down stream would have run $750,000 per year, he explained.
While native freshwater mussels are not as an important food source today as they were in colonial times, mussels are important to Virginia's streams and rivers for a number of reasons, Pinter points out.
"Fresh water mussels are an essential component of our rivers and streams," he wrote. Mussels feed through a siphon by which they draw in and filter water. In the process they remove bacteria, algae and other small particles from the stream, Pinter says.
"Mussels also serve as a food source to many species of fish, reptiles, birds and mammals," Pinter continues. Piles of empty mussel shells left by muskrats and raccoons and other animals are called middens. The empty shells serve as habitat for many stream and shore creatures.
Prior to the invention of plastics in the 1930s, most buttons were produced from mussel shells. Today, freshwater mussel shells from areas of the U.S. provide the "seed" for pearls cultured in China and Tahiti.
Since mussels spend their entire life filtering the water, they are a useful tool in gauging the long-term health of a river or stream, Pinter says.
Preserving and protecting freshwater mussels in Virginia relies heavily on the cooperation of landowners, Watson added. DGIF is working with The Nature Conservancy to obtain a tract of land in Highland County along the Bullpasture to protect mussel populations in that river.
While conservation land purchases help, "Conservation starts with private landowners," Watson said. Will Smith works for USFWS and is trying to increase cooperation with landowners in preserving aquatic species. He and his family helped out Saturday and he added bits of humor to technical conversations.
Smith was all business, though, when speaking about the importance of private landowners in preserving mussel species.
"The fate of these species," he said. "It really does rest with the landowners."
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