freshwater mussels (민물 조개)

[석수]

freshwater mussels

freshwater mussels

 A brail (also called a crowfoot bar) with mussels attached to the hooks. Mississipp River, Illinois, USA.
낚시 바늘에 홍합이 부착된 브레일(까마귀발 막대라고도 함). 미시시피 강, 일리노이, 미국.
 

crowfoot


Timed searches for small bivalves and gastropods (<2 cm length)

For this method we recommend undertaking timed searches in each habitat type for a minimum of 2

person-hours. A complete survey for freshwater snails and small bivalves will include sampling both benthic

surveys and a variety of other substrates including macrophytes, crevices of rocks and wood, other types of

floating debris and leaf litter. For sediment sampling, a “kick net” Surber bottom sampler with a rectangular

or triangular opening should be used in flowing water. Save the sediments from each sample into lidded

buckets for lab analysis or dump the sediments into white trays for sorting and identification in the field,

collecting all specimens with forceps or plastic Pasteur pipettes.

For aquatic vegetation and other loose debris, flush the sample into a bucket or run a dip-net several times

through it, examining the net contents carefully for small snails such as the hydrobiids, limpets, and small

planorbids. Small kitchen strainers and white trays or buckets can be used as cheap and eective alternatives.

For strainers, the mesh should have a maximum diameter of 1 mm to capture small or newly-hatched gastropods.




관련 질문

Are freshwater mussels good for you?

Do all freshwater mussels make pearls?

Are freshwater mussels clams?

Can you cook freshwater mussels?



https://youtu.be/tdJUD03Pn6c

Hand-painted freshwater mussels mounted on TN River driftwood

TENNESSEE SHELL DIVERS


    Freshwater mussels were harvested by Native Americans for thousands of years, as a food source and for use as utensils. The pearls were also highly prized for beads and as decoration on pottery. The modern era of mussel harvest began when a German pearl-button maker immigrated to the United States. When J. F. Boepple arrived in 1887, he was overwhelmed by the seemingly endless supply of mussels in the lakes and rivers of this country. He began an industry that would soon be supplying the world with high quality, beautiful mother-of-pearl buttons that would hold up to severe laundering. By 1920, there were over 200 button factories in the United States. Mother-of-pearl buttons continued to be preferred until plastics became more economical following WWII.


Brailing was the harvest method of choice around the turn of the century and consisted of dragging what was then known as crowfoot hooks, or three pronged metal hooks attached by rope or chain to a long pole. These poles were then dragged along the bottom of the river. In those days, the brail boats were propelled by a 'mule' or underwater sail which was lowered into the river, the current caught the mules and pulled the boats down the river. The mussels open to feed on plankton and algae in the water and when these hooks happened to hit them they would clamp down on them. The brailer would haul up the laden brails every few hours and pick the shells off into the boat. Brailing is still the only allowed method of mussel harvest in some states including Kentucky, and in some states mussel men are required by law to use the underwater sails (mules) to move the boats.


The advent of plastics for button making looked like the end of mussel harvesting. But in the 1950s the Japanese cultured pearl industry discovered the high quality of mother-of-pearl from the United States, particularly the Tennessee River. 



Freshwater Mussels Are Dying—Which Is the Likeliest Culprit?

The list of suspects is long: bacteria, viruses, pollution, invasive species. No matter the cause, the Unionid Mussel Strike Force aims to find out.

THIS STORY ORIGINALLY appeared on Undark and is part of the Climate Desk collaboration.
Anthony Sasson knew something terrible had happened in Ohio’s Big Darby Creek.


Ordinarily, Big Darby cradles 44 of Ohio’s 60 or so species of freshwater mussels. But in October 2016, Sasson, then a biologist at the Nature Conservancy, was one of the first people to notice mussels emerging from the safety of their usual burrows in the creek bed. The die-off was so extensive he could wade into the protected waterway, reach down, and collect a dead or dying mussel with every step. That fall, thousands of mussels—including two federally endangered species—perished without warning or explanation.


At first, it looked like the result of a toxic spill—except all the fish and other aquatic life seemed fine. Early water and tissue analyses ruled out contaminants, algal toxins, parasites, bacteria, fungi, and other pathogens. “We really don’t know what’s happening,” a US Fish and Wildlife Service employee said at the time. A month later, one of her colleagues expressed doubt they ever would. Biologists returned to document the die-off’s survivors, but even today they still don’t know the cause or the extent of the one-time event’s drastic toll. “It’s an enigma,” Sasson said.


In North America, home to one-third of the world’s freshwater mussel species, more than 70 percent of the mussels are imperiled or have been driven to extinction by pollution, habitat destruction, and other human-made hardships. But mass mussel casualties like those in Big Darby are relatively new, and they are happening worldwide. Around the same time as the Ohio incident, thousands of mussels were mysteriously perishing in Tennessee’s portion of the Clinch River, which runs through the Great Appalachian Valley. And over the last decade, similar die-offs from Washington to Wisconsin to Virginia—and overseas in Spain and Sweden—have perplexed biologists. “These are scary and disturbing,” said David Strayer, a retired freshwater ecologist formerly with the Cary Institute of Ecosystem Studies, an environmental research nonprofit in New York state. “Because we don’t really know what’s going on.”

On the case is the somewhat facetiously named Unionid Mussel Strike Force, a collaboration of two researchers at the University of Wisconsin-Madison and a half-dozen other scientists from federal agencies around the country. But in addition to trying to solve a mystery, the Strike Force is struggling against another obstacle long familiar to mussel specialists: apathy.

“It’s hard to rally around a living rock,” said Jeremy Tiemann, an aquatic ecologist with the Illinois Natural History Survey and president of the 550-member Freshwater Mollusk Conservation Society. Even though mussels are largely responsibly for filtering and cleaning freshwaters worldwide, it’s not easy to foster human compassion for them, added Jordan Richard, a US Fish and Wildlife Service biologist and Strike Force member.


Still, in many of the country’s freshwater creeks and rivers, that foundation has been long crumbling. As early as 2004, Ohio ecologists began sounding alarms about declines in the richness of mussels in Big Darby Creek. The long decline, and the more recent decimations, could point to a broader ecological collapse. “I tell people freshwater mussels are not the charismatic megafauna,” the late Ohio State mollusk curator Tom Watters told Columbus Underground magazine in 2019. “They’re not cuddly or majestic or cute.” But mussels, Watters continued, “are the canaries in the coal mine.”
FRESHWATER MUSSELS — distinct from the farmed saltwater varieties typically found on dinner plates—occupy the intersection of water and soil, making them precious to both aquatic and terrestrial ecosystems. As filter-feeders, mussels can digest bacteria like E. coli and other contaminants from the currents they bathe in, including the pharmaceuticals we flush down our toilets and the herbicides we apply to our lawns. What mussels ingest, they break down; some of it they release, and the rest they store as nutrients in their soft tissue and shells. These nutrients include carbon, which the mussels can sequester for the entirety of what is, at least for some species, a century-long life, making them at least a small player in mitigating climate change. In death, mussels still play a role in the ecosystem, feeding muskrats, raccoons, and other riverside vertebrates.