Page, Ariz. - Recent monitoring samples from Lake Powell reveal evidence of microscopic Quagga mussel larvae in the water.
According to Glen Canyon National Recreation Area Superintendent Todd Brindle, the National Park Service (NPS) has accelerated efforts in the laboratory and field to identify the source. Quagga mussel larvae and DNA were found in separate water samples collected near Antelope Point and Glen Canyon Dam.
"We don't know yet if there is a population trying to establish in the lake," said Brindle. "The DNA can last after the organism is dead, so there is a possibility that it could have washed off boats that had been in other infested waters."
NPS aquatic ecologist Mark Anderson said the bodies of four larval mussels were found in four different samples near Glen Canyon Dam. The sampling process kills mussel larvae. It is not known if any of the mussels were alive in the lake.
"One of them had a broken shell, suggesting that it was dead when it was collected," Anderson said.
He explained that testing occurs using two separate methods: DNA and microscopy. The DNA method is more sensitive and potentially detects the presence earlier, but can be less accurate. Detection using microscopes is more accurate but requires an organism or piece of organism that is large enough to be visible in the microscope. NPS is taking samples using both methods at multiple sites around Lake Powell.
Superintendent Brindle said he remains hopeful that the monitoring results are not evidence of an established population of mussels. If it is an early detection, the mussels may not establish and grow into adults.
"Scientists are not sure why but many western waters have shown similar findings and then never developed a noticeable population, such as at Lake Granby, Lake Pueblo, Electric Lake, Red Fleet, Navajo Lake, Grand, Shadow Mountain, Willow Creek, and even Lake Powell in 2007," Brindle said.
In the meantime, NPS officials will continue monitoring and testing.
"It is possible that these results will not be duplicated and a population of Quagga mussels is not developing," said Anderson.
In addition to the water sampling, NPS divers and underwater remote operated vessels will search for adult mussels.
"However, if test results continue to show positive for DNA or if there are adult mussels visible, it could indicate that a population is starting," Anderson said.
If there is a population of mussels, Superintendent Brindle said he is committed to working with all agencies and partners to determine the extent of the population and investigate and implement
strategies for control. Depending on the extent of an early population, removing, wrapping or burying the mussel colony might be effective in preventing additional reproduction.
Anderson said boat inspections will continue.
"Prevention is still the most effective way to fight invasive species," he said. "Continue to clean, drain, and dry your boat and equipment after every use.
Additional monitoring information and updates are posted on the Glen Canyon National Recreation Area webpage at www.nps.gov/glca.