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/