Searching For Zebra Mussels In Wellington Lake
Biologists and aquatic species experts will be checking more than a dozen lakes and reservoirs across Kansas this month.
They’ll be taking water samples to monitor the growth and spread of zebra mussels, an invasive clam that is starting to turn up in new places.
KMUW’s Deborah Shaar takes us through the monitoring process with a team at Wellington Lake in south-central Kansas.
Wellington Lake is three miles long and sits in the middle of open land and farm fields about 10 miles southwest of downtown Wellington. It’s known for camping, fishing and boating, and, this summer, zebra mussels.
“We knew it was coming sooner or later,” says lake supervisor Doug Kinney. “I mean, we went for years, you know. We hung in there a long time without getting them. But it was going to happen.”
Kinney says the lakes in nearby counties have zebra mussels, so it wasn’t a surprise when his staff detected the mussels in Wellington Lake in June. Workers were moving a few buoys to different areas and found several large zebra mussels attached to the anchor ropes.
The small clams are shaped like the letter “D” with a hard, yellow-brown shell filled with alternating light and dark stripes. They can grow up to two inches long.
Kinney says the presence of zebra mussels might mean a little more work and maintenance, but it won’t change recreation at the lake.
“Some people I guess when you tell them, they are kind of apprehensive about being in the lake. They think it’s something really bad. It’s not,” Kinney says. “We just tell people to make sure they wear shoes. Even their children wear shoes wading in the water.”
The protection is needed because zebra mussels have a razor-like shell.
Once the Wellington discovery was verified, the state added the lake to its list of “aquatic nuisance species” waters, and new regulations went into effect.
“We’re up to about 25 waters now … out of about 200 public waters,” says Jessica Howell, aquatic nuisance species program coordinator for the Kansas Department of Wildlife, Parks and Tourism.
Howell says the zebra mussel population has been spreading throughout the state for the past 12 years. The first instance was detected in El Dorado Reservoir in 2003.
“And since then we’ve have slowly detected new populations. Not every year...but most years since then,” she says.
Zebra mussels are considered an “aquatic nuisance species” because they attach to any hard surface in the water, such as docks, rocks or water intakes of power generating plants. If they are not controlled, the mussel population can grow quickly and cover each inch of solid surface. That accumulation would not only weigh down a structure, but could also clog pipes and reduce the flow of water.
“We estimate that it probably costs Kansans millions of dollars each year to control this problem,” Howell says. “As we see more waters affected, the cost will increase over time.”
And that’s why twice a year, usually in the spring and then again in September, Howell and her staff assess the situation at the aquatic nuisance designated waters.
On a recent Tuesday, a team of two is on Wellington Lake in a small aluminum fishing boat with a crate full of testing supplies and a few nets. The first stop is not very far from the shoreline.
The team pulls a buoy out to see if they can find any zebra mussels on it. Once the buoy rests on the edge of the boat. Howell and technician Ryan Easton carefully look and feel for zebra mussels. Howell runs her hands over the mud-covered buoy and as much as the anchor line as she can safely reach without tipping the boat over.
She pulls off a large dark mussel that she says is about two to three years old. Then a smaller one. And another, until her hand is full.
“Once they find something hard, even if it is another zebra mussel shell, they do start to attach and grow kind of in clusters,” Howell says. “That’s what we are seeing here with this smaller one that was actually attached to an older individual.”
They head out to the middle of the lake to collect water samples. The zebra mussels they pull off the buoy go into a plastic vile. Howell says zebra mussels can be destroyed in many ways, but to actually eradicate a population is very difficult.
“Usually when we find them, they are widespread throughout the lake and in multiple year classes indicating reproduction,” Howell says.
They use a modified Wisconsin net to take water samples, Howell explains.
“And what that does is that it has a very fine mesh on there so it will pull out small particles from the water and kind of concentrate those down,” she says.
The water samples will be checked under a microscope to confirm whether there is reproduction, and if larvae are present in the water. The larvae can’t be seen, so they can easily spread among bodies of water through boating, fishing or the natural flow of rivers.
At the far side of the lake, Howell and Easton leave the boat and lie flat on their stomachs on the dock so they can reach the underside. Their hands move through the thick, slimy algae that covers the submerged bottom, prime habitat for young zebra mussels.
“It’s intimidating the first time you do it!” Howell says. “It’s really intimidating when we do our swim. Of course all you can think about during the time is, you know, ‘Is there a snake that’s going come get me?’ Or ‘What’s coming out from under that rock?’ But you get over it."
In no time, their experienced hands find a juvenile mussel from this year’s spawn. It’s just a tiny speck, smaller than a grain of rice. Technician Ryan Easton says it feels like coarse sand paper.
“They’re pretty east to identify once you know what you are looking for,” Easton says. “Fortunately the juveniles look a lot like the adults at that stage so they have the stripes on them and they have that very distinct ‘D’ shape.”
The last check of the day is on the other side of the lake, along a shoreline full of rocks.
Howell pulls up some softball-sized rocks. Small zebra mussels are attached to each one. Based on all the sampling and searching, Howell says Wellington Lake has an established zebra mussel population, so control strategies will be used to keep the numbers in check.
The key to success, she says, are preventive measures to keep the infested water from spreading.
“If you are using the water, we recommend that you clean, drain and dry all of your equipment. That could be anything to a duck blind, to a boat to a minnow bucket,” she says. “As long as you are using or touching the lake water, we recommend that you thoroughly inspect and remove any plants, animals or mud from your equipment. You drain everything sufficiently.”
As long as lake visitors follow these steps, Howell is optimistic that zebra mussels are one aquatic nuisance species that can eventually be contained. She says new sightings are the only way they can keep track of Kansas waters, so if you happen to find a zebra mussel, report it.
Follow Deborah Shaar on Twitter @deborahshaar.
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