They can clog up waterways. Their sharp shells pose hazards in sandy beaches. They can fundamentally alter local ecosystems. And there’s virtually no way to stop them.
They’re zebra mussels, and they’ve just infested Omaha’s Cunningham Lake.
Last week’s discovery of zebra mussels at a heavily trafficked fishing and boating spot like Cunningham Lake raises concerns about the likelihood that they might spread further to other lakes—and with Fremont home to its own hub for boaters and beachgoers in its State Recreation Area, that concern is especially prescient.
The invasive species of mussel is not native to the United States. They first came here from Europe, hitching a ride in the ballast water of ships in the late 1980s, and establishing themselves in the Great Lakes.
But they’ve since spread to other waterways across the country, as boaters travelled from lake to lake, waterway to waterway, often inadvertently bringing the invertebrates, noted by their zebra-striped shells, along. And once they find a new home, it’s very difficult to remove them, according to Dr. Chintamani Manish, a professor of biology at Midland University.
“They are prolific breeders and they don’t have a natural predator, so there’s nothing to stop them, and they can outcompete the normal mussels that we have here,” Manish said. “They go from very small numbers to very large numbers very quickly.”
The mussels spread easily, too, experts say. They may moor to the hull of a boat, or their microscopic young, known as veligers, might accumulate in water that gathers in the boat. If the boat isn’t properly cleaned or dried out, they may establish themselves in any subsequent body of water that the boat enters.
They bring with them a host of problems, said multiple experts interviewed by the Tribune. They are filter feeders that take in water to filter out plankton or other food, creating added competition that upsets the local food chain. They seek out flowing water—drain pipes, for instance—and can create clogs. They can make water clearer, which promotes growth of unwanted vegetations. And, in beach areas, like those here in Fremont, their sharp shells might pose hazards for bare-footed beachgoers.
The troublesome molluscs first arrived in Nebraska in the early 2000s after being discovered on the Offutt Air Force Base, said Dave Tunink, the fisheries assistant division administrator at Nebraska Game and Parks. Efforts to remove them there have been unsuccessful.
They’ve since been found at Zorinsky Lake, along the Missouri River, and at Lewis and Clark Lake—there, people are advised to wear boots or foot covering when walking on sandy beaches, Tunink said.
In mitigating the spread of zebra mussels, Fremont has one distinct advantage, Tunink said.
It’s effectively a sand pit, with few hard, rock surfaces that normally provide attractive homes for zebra mussels.
“But they do have boat docks where they could attach,” Tunink added. “So they wouldn’t be as big an issue there, population-wise, I don’t think, but you don’t want them in areas where people enjoy beaches.”
And even without the rocky surfaces, there are plenty of surfaces that zebra mussels could find, says Manish. On buoys, docks and piers, the mussels could still wreak some havoc.
“I the absence of a predator, something that controls them naturally like fish or other things, they might not establish as quickly as they might at a rocky place, but I would be worried if it came to the Fremont lakes—they find a way,” Manish said. “There’s enough places for them to find some place to latch onto, and once they do, they keep going.”
To prevent the spread of zebra mussels, Game and Parks is encouraging boaters to carefully clean, drain and dry their boats before launching them in different bodies of water.
To clean, boaters should rinse their boat, trailer and equipment with hot tap water.
Vinegar can also be used to kill mussels.
Then, boaters should pull the plugs from the bilge and live well and tilt the engine to drain water upon leaving a water body. Boats should then be dried for at least five days before entering a new body of water.
A towel can be used to speed up the process.
Boats transporting zebra mussels can be impounded and fined up to $500, according to a Game and Parks press release.
The City of Omaha, University of Nebraska Cooperative Fish and Wildlife Unit, the U.S. Army Corps of Engineers and Game and Parks are planning on increasing surveillance of boaters and anglers to increase awareness of the infestation, and further action is being determined.
Other bodies of water pose unique concerns. Over by Lake North and the Loup River, a zebra mussel infestation could affect operations for the Loup River Public Power District, headquartered in Columbus.
The same is true for other power districts that rely on hydropower.
“We think about it all the time,” said Ron Ziola, vice president of engineering for the Loup River Public Power District. “It is a concern.”
There is signage out there reminding boaters to dry out their boats and jet skis before entering the area water, Ziola said. They try to spread the message over social media, too.
“We have trash racks at the intake to our hydro facilities,” Ziola said. “Well they would populate on there to the point where water couldn’t get through them, so they would actually totally stop off the flow of water which would not allow us to generate with our hydro facilities.”
“If these things got into our Lake North, they would be all up and down the Platte River, all up and down the Loup River, and they would be a major detriment to our hydro facilities,” he added.
Others in the conservation world are stressing the importance of following proper protocol.
“People cannot just ignore this and think it’s not a big deal—it is a big deal,” said Paul Lepisto a regional conservation coordinator who does work along the Missouri River for the Izaak Walton League of America. “We can’t just go out and play like we used to play and fish like we used to fish. You’ve got to take those couple minutes every time you’re out and make sure that you’re not spreading something from one water body to another.”