Zebra mussel clusters like this one from the Great Lakes are wreaking havoc on many waterways in the U.S., but the aquatic hitchhikers have not yet made it to the Columbia River Basin. Photo courtesy of Great Lakes Environmental Research Laboratory licensed by CC BY-SA 2.0.
By Susanne Wright. April 12, 2018. Twelve hundred miles in length, birthed in the Canadian Rockies and ending at the Pacific Ocean, the Columbia River is the lifeblood of the Pacific Northwest. Its vast waterways sustain commercial fisheries, industry, agriculture, recreation and wildlife across seven states. Yet what is missing in the Columbia River may be its most important asset. Our national scenic waterway has not yet been invaded by a particular foreign aquatic species, but an infestation of migrating mussels from eastern Europe is imminent.
Living in the Northwest, you may be unfamiliar with the term aquatic invasive species (or AIS) as it relates to zebra and quagga mussels. A combination of prevention, monitoring and sheer luck has so far protected us from their arrival. Other states are not as lucky.
Caught unaware, 24 states and watersheds across the country are suffering the economic and biological damage of an AIS infestation by two ‘top priority’ species: zebra and quagga mussels. Rarely spoken of outside fishing industries and agencies pledged with protecting our watersheds, these invasive species pose a serious threat to our rivers and lakes.
How did these freeloading parasites arrive in U.S. waters?
Like most parasitic transmissions, they hitchhiked. In the late 1980’s, microscopic zebra and quagga larvae, native to the Caspian and Black Seas, were pumped into the water ballast tanks of commercial freighters departing for the Great Lakes of North America. Upon reaching harbor, the foreign vessels unwittingly discharged infested ballast water into the Great Lakes water system.
With no natural predators these thumbnail size invaders quickly flourished into the trillions, ravaging the Great Lakes and downstream waterways, and decimating native fish and clam populations of the Eastern seaboard. In the span of two decades, quagga mussels irrevocably altered the ecosystems of the Great Lakes region. In 2011, The Muskegon Chronical estimated a stunning 950 trillion quagga mussels populated the bottom of Lake Michigan.
Zebra and quagga mussels cling to whatever surface is most readily available, including boat propellers that oftentimes move from one water body to another. Photo courtesy of Utah Division of Wildlife Resources licensed by CC BY-NC-ND 2.0.
Silent and unrelenting, the mussels migrated west on the bottoms and in the bilge water of trailered boats, clinging to fishing gear, kayaks and inflatables, progressively infecting hundreds of inland lakes and six major rivers. In 2007 the quagga mussel jumped the continental divide and was discovered in California’s Lake Mead—a move that places the Columbia River Basin atop a razor’s edge for potential infestation. It takes only one contaminated boat to introduce zebra or quagga mussels into a new water body, and once it occurs and becomes established, eradication is impossible. Not just difficult. Impossible.
An invasion of unstoppable, indomitable creatures has all the makings of a matinee doomsday flick. But how worried should we be of a potential infestation in the Columbia River and its tributaries?
Paul Heimowitz, regional invasive species specialist with the U.S. Fish & Wildlife Services Pacific Region, sounds the alarm: “These invaders are truly game changers, permanently scarring communities and aquatic habitats wherever they take hold. If invasive mussels established in the Columbia River Basin to the extent they have in other parts of the U.S., we should anticipate major ecological and economic harm.
“They can damage recreational boat engines and reduce boating access. They can significantly increase the cost of hydropower and municipal water operations. They can litter popular beaches with their sharp and smelly shells. They can reduce native fish and wildlife abundance. They can transfer contaminants up the food chain into fish and birds that humans eat.”
How do these tiny freshwater bivalves cause such damage?
Native shellfish like this Great Lakes unionid mussel are frequently colonized by zebra mussels. Photo courtesy of NOAA Great Lakes Environmental Research Laboratory licensed by CC BY-SA 2.0.
For one, they are highly reproductive. A zebra mussel can produce up to one million eggs per spawning season. They are also the only freshwater mussel in the US to have an external organ called a byssus: strong, glue-like threads that attach to almost any hard surface. They heavily colonize underwater rocks, boat hulls, marine docks, municipal water intakes and pipes. Merciless as they are prolific, zebra mussels even attach themselves the outer shells of other mussels and crayfish.
Zebra and quagga mussels are also incredibly efficient filter feeders. Filtering up to a liter per day, they remove substantial amounts of phytoplankton and zooplankton from rivers and lakes, altering the food web and starving native fish populations.
Likewise, their enormous filtering capacity increases water clarity, allowing sunlight to penetrate deeper into water columns and triggering unnatural vegetation growth, which in turn reduces oxygen levels and adds to more fish die-off. And considering the salmon’s river-to-ocean migration cycle, an invasive mussel infestation in the Columbia could have devastating effects on an already fragile fishery, potentially crippling Oregon’s $149 million commercial fishing industry and further diminishing local sport fishing opportunities. A Northwest Conservation Council study estimates the cost to loss of native species habitat could be in the tens to hundreds of millions.
Blaine Parker, a biologist with the Columbia River Inter-Tribal Fish Commission, explains the severity of concern. “The Commission and its Member tribes take the threat of an invasive mussel infestation very seriously. Commission staff have been directly involved with Federal and state agencies for the past two decades. The Columbia and its tributaries and the native fish and wildlife have been and continue to be impacted by wide variety of threats. However, aquatic invasive species are a threat that could easily upset the balance of tribal restoration efforts for salmon and steelhead, permanently.
“Unlike land based invasive species, aquatic invasive species are more difficult to detect, and eradication or even control is nearly impossible in aquatic ecosystems. Prevention is the tool to limit the spread of aquatic invasive species.”
Parker warns of a potential threat that may be difficult to envision, since, as humans, we have a tendency to ignore approaching danger until it arrives, but he reminds us of what is at stake. “Invasive species could have permanent impacts on the Columbia River that could cover hundreds of miles,” he says. “We must remain vigilant. It is a goal of mine to share not only data with the public but spotlight how a serious aquatic infestation could change our waterways, and the damaging economic and cultural impacts to regional tribal fisheries and their communities.”
Mussels migrate wherever water flows, which means an AIS invasion has the potential to affect more than fishing industries. Zebra and quagga mussels also pose an enormous threat to our hydropower infrastructure.
There are eleven Federal hydropower dams located along the Columbia River, and altogether these dams supply three quarters of the power supply to our region. Looking ahead at the remedial costs of an infestation, The Bonneville Power Administration concluded that zebra and quagga mussels have collectively cost the United States an estimated $5 billion in prevention and control, more than any other aquatic species.
In preparation for a worst-case scenario, The Northwest Conservation Council recently prepared a plan in the event of a mussel invasion. The plan estimates the combined economic impact to hydropower and hatchery intake and cooling valves, fish bypass facilities, marina, docks, boating facilities, and loss of hydropower generation could be hundreds of millions per year. According to the Council’s research, “the impact could be especially troubling in the Columbia River and its major tributaries, as mussel colonies form rock-hard mats of shells that can clog water intake and delivery pipes, infest hydropower infrastructures, adhere to boats and pilings, foul recreational beaches, compete with native mussels, and disrupt food webs and the biological functioning of aquatic habitats.”
Despite a gloomy outlook, it is not too late for action. Public awareness and prevention is our best defense. To that end, local, state, and federal agencies have undertaken an ambitious education and monitoring campaign to alert the public, and particularly boat owners, about zebra and quagga mussels. Area agencies issue information on billboards near lakes and rivers, articles in boating and fishing magazines, posters and brochures at marinas and boat landings, and brochures packaged with fishing licenses. They stress boaters be aware that most mussel transfer between water sources occurs by infested watercraft, since adult mussels can survive for up to fifteen days out of water.
Parker explains: “CLEAN, DRAIN, and DRY is our mantra. By cleaning, draining, and drying your watercraft, you eliminate the organism, drain and dry the habitat for the organism on your boat. Watercraft are a primary vector to spread aquatic invasive species, but any action that involves the movement and release of water from one location to another has the potential to spread aquatic invasive species.”
A sign posted near Lake Mead reminds boaters of the importance of cleaning, draining and drying their boats. Photo by J.N. Stuart licensed by CC BY-NC-ND 2.0.
Commercial and sport fisherman are already taking notice. Ernie Delgado, a Pacific Northwest fisherman, says there is ample signage instructing boaters to clean and dry their watercraft and equipment posted at cleaning stations along the Oregon and Washington coastline. “It’s a big deal,” he says. “We sure don’t want mussels here. The synopsis that comes with a new fishing license tells all about mussels and how to prevent them too, how to wash your boat, engine and propeller before entering other rivers.”
While watercraft users are the primary source of mussel transfer, it is important we all learn to prevent mussel introduction and spread. Paul Heimowitz says it best: “It only takes a few hitchhiking mussels, including their microscopic larvae, to start a region-wide invasion. Therefore, anyone who enjoys water recreation can literally make a difference in protection of the Columbia Basin. Always thoroughly clean, drain, and dry your boat, boat trailer, fishing gear, water boots, and other items after you use them in rivers and lakes. Get mussel-minded by visiting websites like 100th Meridian, which include information on how to report a suspected invasive mussel in the Northwest. Early detection can help save the day!”
More AIS prevention information can be found in this US Fish and Wildlife video at 6:05 minutes, and at SHARE the White Salmon.
