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DROUGHT LEAVING SOME FRESHWATER MUSSELS STRANDED; CONCERN REFLECTS GROWING AWARENESS OF ANIMAL'S IMPORTANCE

August 21, 2012

Mussels hidden beauty
Long treasured for their inner beauty, native mussels are now recognized for their priceless eco-services.
WDNR Photo

MADISON - The drought, now categorized as severe to extreme in the southern half of the state, is stranding mussels in shallow waters this summer and leading to an increase in calls from citizens asking how to help the filter-feeding mollusks.

"We're getting calls from people concerned about mussels left high and dry from the drought," says Lisie Kitchel, Department of Natural Resources conservation biologist and mussel expert. "The mussels try to reach deeper water, but water levels are dropping in some cases faster than the mussels can move to safety."

Kitchel says that if people see mussels that are stranded, "go ahead, pick them up and chuck them into deeper water."

Don't worry about getting them right side up, she says. Mussels, like snails, have a foot that they use to crawl with. Mussels have been documented to move up to 30 feet a day and can dig themselves deep into the river or lake bottom, she says.

The drought is another complicating factor for mussels, a freshwater animal whose fortune has actually improved in many ways. Perhaps prime among them is growing recognition of their vital role in ecosystems and public concern for them, Kitchel says.

"The fact that we are getting so many calls is encouraging because it says there are people out there who are watching their streams," she says.

Wisconsin has more than 50 native mussel species, more than half of which are endangered, threatened or listed as species of concern. Mussels are found in shallow areas of lakes and rivers, but the vast majority of species are found in rivers, where mussels find the flowing water that delivers the food and oxygen they need to survive.

Mussels' fortunes are reversing on many waters, however, for a variety of reasons. The animals are the featured success story for the August installment of DNR's year-long web series celebrating the 40th anniversary of the state endangered species law. Go to dnr.wi.gov and search for ER 40, to find the feature and the previous months' featured species.

Overharvesting, water pollution, and dams that blocked the flowing water mussels need led to their decline in the 20th century. Kitchel is encouraged that mussel populations are increasing in many waters again, thanks to protections afforded by the state and federal endangered species acts, and also, in large part to improved water quality since the 1972 Clean Water Act made it illegal to discharge wastewater without a permit.

Now, appreciation for mussels' vital role in aquatic ecosystems is growing, eclipsing their historically recognized value. For centuries, Native Americans used mussels for food, tools and decoration. In the early 1800s, mussels were harvested for their pearls, but it soon became apparent that there was a low return on the work because freshwater pearls were few and far between. From the 1880s to the 1940s, mussels in Wisconsin and elsewhere were used to make buttons until plastic buttons replaced them. After that era, mussels from the Upper Mississippi River became a mainstay of Japan's cultured pearl industry. Mussels collected from the river were shipped to Japan where they were sliced up and turned into the seed from which pearls were cultured, Kitchel says.

Overharvest of mussels on the Upper Mississippi River led to closing the commercial harvest of mussels.

Now, mussels' role in ecosystems is starting to shine as scientists learn more about these animals, Kitchel says. "Mussels are our freshwater filters," she says. A single mussel can filter a gallon or more of water a day, removing sediment and nutrients that can fuel algae blooms, as well as pesticides and heavy metals like mercury that can build up in fish and wildlife and the people who eat them.

Mussels are also food for many animals, including muskrats, otters, raccoon, ducks, wading birds and fish. And, because of their sensitivity to pollution, they are sentinels, their health a barometer of what's going on in the river or lake ecosystem.

Protections afforded by the state and federal endangered species acts require that lake and river projects are reviewed to make sure steps are taken to avoid impacting mussel populations. DNR, the U.S. Fish & Wildlife Service, dam owners and other partners are working together to reverse the decline of rare species and to protect common mussels as well. Mussels stranded from reservoir drawdowns are saved and put back into deeper water. Mussels propagated at the federal Genoa Fish Hatchery, and through research to find the right fish hosts, are being released back into waters. A critical link in mussels' lifecycle is they must have a host species, usually a fish, to complete their life cycle. Some mussels species use only one type of fish, others use a number of fish species.

And citizen interest in mussels is growing. Two years ago, the Wisconsin Mussel Monitoring Program started and has since trained more than 200 volunteers about the value of Wisconsin freshwater mussels and how to identify them. Many of these people and school groups are documenting what species occur and where they occur in Wisconsin lakes, rivers and streams.

Ten "hidden" pearls about mussels that you might not know:

  1. Mussels require a fish host to complete their life cycle.
  2. One mussel uses the mudpuppy as its fish host, the salamander mussel.
  3. Mussels use fish, crayfish, and insects 'lures' to attract their fish host.
  4. Mussel lures actually behave like the animal they are trying to mimic by flapping like a fish, flipping like crayfish or moving like an insect.
  5. Some mussels grab ahold of the head of their host fish to ensure the young get on the fish gills.
  6. One mussel actually fishes for a fish host by putting its fish-shaped egg mass out on a line of mucus.
  7. Mussels live to be 20, 30, 40 or more years and some have been aged over 100 years old.
  8. Scientists determine mussels' age similar to how they age trees - by counting the rings. Mussels stop growing in the winter and start growing again in spring.
  9. Mussels are great concentrators of contaminants, removing them from the water column.
  10. Mussels 'aerate' the river bottoms just like earthworms aerate the soil.

FOR MORE INFORMATION CONTACT: Lisie Kitchel (608) 266-5248

Last Revised: Tuesday, August 21, 2012




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