National Park Service Issues Mussel Monitoring Update for Lake Powell
Recent monitoring samples from Lake Powell have revealed evidence of microscopic Quagga mussel larvae and the National Park Service (NPS) has accelerated laboratory and field efforts to identify the source, reported Glen Canyon National Recreation Area Superintendent Todd Brindle. 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 provided additional details on the sampling results. "The bodies of four larval mussels were found in four different samples near the Glen Canyon Dam. The sampling process kills mussel larvae so it is not known if any of them were alive in the lake," stated Anderson. "One of them had a broken shell, suggesting that it was dead when it was collected."
Anderson 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. Samples are taken using both methods at multiple sites around Lake Powell.
Superintendent Brindle 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, said Brindle. "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."
In the meantime, monitoring and testing by the NPS will continue. "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 be used to 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.
"We will continue the boat inspections that are currently in place," Anderson stated. "Prevention is still the most effective way to fight invasive species. 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/parknews/musselupdate.htm.