Researchers at Washington State University are preparing for a Northwest invasion of the zebra mussel - a small, distinctly striped and rather tenacious freshwater mollusk that can quickly encrust underwater surfaces. The mussels have caused significant damage in other parts of the country and pose an enormous risk to the hydroelectric infrastructure, recreational facilities and unique ecological system of the Columbia River Basin.

"Once they are established in the water, they are almost impossible to eradicate,” said Stephen Bollens, director of the WSU School of the Environment and lead investigator for a $630,000 grant from the Bonneville Power Administration to ramp up preparations.

The Columbia River Basin is one of the last major river systems in the U.S. still free of zebra mussels and the closely related quagga mussels; but possibly not for long. According to the Columbia Basin Bulletin website, boat inspections in Washington, Idaho and Oregon in 2012 identified more than 110 pontoons and trailered boats carrying these invasive species.

"An important step in mitigating or reducing the negative effects of zebra and quagga mussels is to determine when and where they might be introduced into the water system,” said Bollens.

Every one of the Columbia River Basin’s 8 million residents is a stakeholder when it comes to invasive species, he said. Electric companies, power consumers, recreational boaters, ecologists, municipalities, irrigation farmers and Native American fishing communities could all be affected if zebra or quagga mussels gain a foothold in Northwest waterways.

The grant will establish cooperative monitoring standards, increase the quantity and quality of water sample analysis and investigate potential ecological impact. It also will enable strategic recommendations on where to distribute resources, such boat inspections and cleaning stations, to slow the spread of the zebra mussel.

 

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Spreading west

"The entire West is on high alert,” said Tim Counihan, research fishery biologist with the U.S. Geological Survey’s Western Fisheries Research Center in Seattle and Bollens’ partner in the mussel investigation.

Both species are native to Eurasia and most likely hitchhiked across the Atlantic in the ballast water of shipping vessels. Zebra and quagga mussels were first identified in North America in 1988 in the Great Lakes region.

Within a decade, quagga colonies had spread the full length of the St. Lawrence Seaway and throughout the Great Lakes system. Zebra mussels were also thriving, and established colonies could be found in the Great Lakes and along the Mississippi River watershed, from Lake Superior to the Gulf Coast (see map here). Due to overland transport of recreational boats and water equipment, both species have spread to popular inland lakes and rivers in Colorado, Utah, Arizona, Nevada and California.

Calculating the cost

Zebra and quagga mussels have already caused more than $1 billion in damage in the Great Lakes region: they have clogged or covered everything from fish ladders and spillway grates, to irrigation and municipal water intakes, to dock pilings and outboard motors. In the process, native mussel colonies and small crustaceans such as crayfish often are smothered and destroyed.

For the Columbia River Basin, the costs could be equally staggering. The basin includes more than 30 hydroelectric dams and thousands of irrigation and municipal water intakes. It welcomes countless recreational boaters, anglers and swimmers each year.

Invasive mussels can affect entire ecosystems. Although they are individually small, large colonies can filter enormous quantities water each day. They consume algae and plankton, leaving the water looking clean and clear but disrupting the native food chain.

"These small animals have the potential to wreak hundreds of millions of dollars worth of economic damage to the Columbia River hydroelectrical system, as well as impairing native salmon habitat and other food webs,” said Counihan.

 

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Needle in an aquatic haystack

Identifying the mussels early in their development is critical to mitigating economic or ecological impact. Microscopic mussel larvae - called veligers - float freely in the water for several weeks before attaching to a suitable surface. A significant amount of human skill and time is required to scan water samples and identify both the presence of veligers and their species.

Advanced particle analysis and imaging technology can quickly and accurately recognize the distinctive "Maltese cross” pattern of zebra and quagga veligers. WSU researchers are hopeful this new technology will give them an edge in the fight to protect the region.

"If we can standardize and speed up water sample analysis, we can look at more samples from more locations and hopefully take action before the mussels become a problem,” said Gretchen Rollwagen-Bollens, a professor at WSU Vancouver and co-investigator on the BPA grant.

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