Initial tests conducted in 2011 and 2011 at the Southwest’s Lake Mead by Portland State University researchers indicate the invasive quagga mussels could well survive and grow in Columbia River waters.
“We found that 68 percent of the mussels raised in untreated Columbia River water gained weight -- they grew. This does not bode well for the Columbia,” researcher Brian Adair, a Portland State graduate student, said.
He drew water from the Columbia, and the Willamette River, and transported it south to test how quaggas responded to untreated water, water treated with various amounts of calcium, and water at various temperatures.
The mussels survived better and had a stronger growth rate in the untreated Columbia water as opposed to untreated Willamette water. Survival was 19 percent of mussels reared in Willamette water.
The preliminary research results were previewed for Northwest Power and Conservation Council during its meeting Feb. 13 in Portland. A final report on the water suitability research as well other related mussel topics is up for delivery in September to the Bonneville Power Administration, which is funding much of the work.
Northwest interests are wary of the mussels’ approach. The quagga mussels, and their zebra mussel kin, were first introduced in the Great Lakes area in the late 1980s or early 1990s. They are now known to occur in many waterbodies in the Midwest and Northeast and more recently the Southwest, including California. The known occurrences of quagga mussels closest to the Northwest are in northern Nevada.
When able, they grow and multiply very quickly, attaching themselves to hard surfaces such as rocks and manmade infrastructures. Maintaining infrastructure, such as dams and irrigation and fish passage facilities, has already proven in eastern United States and locations such as Lake Mead to be enormously expensive.
The mussels are well established at “Lake Mead and finding their way north toward our water bodies,” said Mark Systma, associate vice president for research at PSU.
“This appears to confirm our fears that mussels would grow well in the Columbia,” Council Chair Bill Bradbury said of the research. “The results underscore the importance of the boat inspection programs and other efforts in our states to keep mussels out of Northwest waters.”
The PSU researchers say the Columbia River basin water chemistry and temperature are sufficient, if not ideal, to support the invasive species. A high percentage might survive and grow, but has yet to be verified whether they can reproduce in the Columbia, which has calcium levels near, but less than, what seem to be optimal for the mussels.
“Our conclusion is that the Columbia appears to be suitable for quagga mussels,” Adair said. Because of lower calcium levels, primarily, mussels did not grow as well in Willamette River water.”
“The Willamette may be marginal habitat, but mussels probably could adapt,” he said.
The Portland State team did not include the Snake River in their research, Adair said, “but we know the Snake has higher calcium than the Columbia.”
Dime-size zebra and quagga mussels adhere to boat hulls and submerged structures, including dams and dock pilings, and form thick hard mats of shells that can not only block water passage but also disrupt the environment by depleting nutrients for other species and ruining fish habitat.
They are transported from place to place primarily on infested watercraft.
Mussel infestation is a significant concern for states and dam operators in the Northwest. The Council’s Independent Economic Advisory Board estimates that the potential cost of controlling an infestation and cleaning hydropower and fish-passage facilities if the mussels take hold here would easily be in the tens of millions of dollars per year -- and hundreds of millions in total costs to protect lakes and rivers, inspect and decontaminate infested watercraft, and address other impacts.
Adair and the Portland State research team focused their research on quagga mussels. They collected mussels from a dock in Lake Mead, Nev., and submerged them in buckets of untreated Columbia and Willamette river water. Then they gradually adjusted two critical growth factors for mussels -- calcium concentrations and water temperature -- and observed how the mussels reacted.
In the research setting, optimal growth of quagga mussels occurred at calcium concentrations between 35 and 50 milligrams per liter of water, and temperatures of 64-68 degrees Fahrenheit. Calcium concentrations and water temperature in the Columbia River vary throughout the year from about 12-22 milligrams of calcium per liter, and from 37-76 degrees Fahrenheit.
The researchers also tested several types of surface coatings to see how well they inhibited mussel growth. Such coatings, painted on submerged surfaces, present a slick surface that can either prevent mussel attachment or be more easily cleaned of mussels and other undesirable organisms with high-pressure water. The coatings are not toxic, but they are expensive -- about $130 per square meter.
Panels of several materials -- treated and untreated concrete, and steel -- were submerged in the Columbia River water. After three months, the results are encouraging: some products performed better than others, depending on the surface material, but quagga mussels could not adhere to any of the surfaces.
The experiment will continue until the panels have been submerged 15 months; the researchers then plan to conduct a similar test at the infested San Justo Reservoir, a Bureau of Reclamation project about 90 miles south of San Francisco, and then prepare a cost estimate for treating a Columbia River dam.