Needle in a haystack

UM researchers hunt for invasive mussels 

For a group of University of Montana researchers, the iced-over waters of Flathead Lake offer some hope that a devastating invasion can be staved off.

"I don't think I've ever felt such a sense of urgency," says Gordon Luikart, a scientist and professor of conservation ecology and genetics with the Flathead Lake Biological Station. Luikart and other scientists from around the state have been on high alert since the mid-November discovery of invasive mussel larvae in the Tiber Reservoir, east of Shelby. If the mussels spread, they threaten to cost the state millions and reduce access to waterways. Right now, while the weather is too cold for the mussels to reproduce, researchers are combing watersheds statewide for microscopic evidence of their presence.

"Like cancer, if it's just one little spot in your body you can get it out, but if it spreads, the waterway is lost forever," Luikart says.

Zebra and quagga mussels, both common invasive species, can be as small as a sesame seed. Flathead Lake's surface area is 197 square miles. Luikart employs an emerging technology called environmental DNA, or eDNA, to make the hunt easier. The eDNA process allows scientists to collect samples from air, water or soil and detect a specific organism's presence from a mere strand of DNA. Luikart has done extensive work isolating the genetic markers that identify invasive mussels as distinct from native species.

"We can detect single molecules in the air or in water, which is amazing," Luikart says. "But the other side of that is, you're so vulnerable to contamination, or getting DNA you thought came from the environment, but it's from your equipment, or you, or your breath, if you've been in a room with lots of DNA samples."

To sample for invasive mussels in Flathead Lake and waterways around the state, Luikart's team ventures out on a boat and drags a plankton net through the water for a few hundred yards, enabling a large sample size. Material collected by the net is rinsed in ethanol, scraped into a tube and taken back to the lab. The nets are cleaned thoroughly in a 50 percent bleach solution to prevent cross contamination.

click to enlarge A single female zebra mussel can produce 1 million eggs in a five-year life- - span, causing massive overpopulation. University of Montana researchers are among scientists across the state searching for evidence of invasive mussels so they can be eradicated. - PHOTO COURTESY OF FLATHEAD LAKE BIOLOGICAL STATION
  • photo courtesy of Flathead Lake Biological Station
  • A single female zebra mussel can produce 1 million eggs in a five-year life-span, causing massive overpopulation. University of Montana researchers are among scientists across the state searching for evidence of invasive mussels so they can be eradicated.

The race is on to find and eradicate invasive mussels before they can start reproducing in summer, putting most of the biological station's other work on hold for now. Sampling in subzero winter temperatures is "interesting," as Luikart puts it. His team plans to drill holes in the ice and set up tents to block the wind, although the tents won't provide much protection for the scientists.

It takes about a month to get results from eDNA samples, according to Tom Bansak, assistant director of the biological station. He and Luikart are appreciative of the state's emergency response—Gov. Steve Bullock declared a statewide natural resource emergency Nov. 30—but they'd like to obtain funding for more staff to speed up the processing of samples.

Bansak—who recently published a paper on invasive mussels titled "Be Afraid. Be Very Afraid"—emphasizes that finding the mussels and preventing their spread may save the state tens of millions of dollars. Zebra and quagga mussels arrived in North America in the late 1980s and proceeded to wreak havoc on waterways throughout the Midwest. Mussels are prolific breeders and filter feeders, consuming all available food sources and decimating fish populations. They can grow inside pipes, thus clogging irrigation systems, hydroelectric dams and municipal water sources. Beaches are ruined by the razor-sharp mussel shells. So far, Minnesota is the only example of a state that's detected mussels and moved quickly enough to prevent a statewide infestation.

"Once you have widespread reproduction, there's no hope of getting rid of them under current methodologies," Bansak says.

For now, the average citizen's best defense is to "inspect, clean, drain and dry" their boats, which are the most common vectors for the mussels' spread. Luikart says the biological station is considering a system for citizens to collect and drop off samples for testing.

"It's going to be devastating. It's going to be nasty," Luikart says. "Life's going to get more expensive when these things show up in nearby lakes."

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The original print version of this article was headlined "Needle in a haystack"

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