Biologists hopeful that the alien invaders haven’t started breeding yet
By Summit Voice
SUMMIT COUNTY — Non-native quagga mussels have gummed up waterworks and fouled ecosystems across the country and now, for the first time, they’ve been confirmed in Lake Powell, the great southwestern reservoir that is a key part overall water storage in the Colorado River Basin.
The National Park Service recently identified 14 adult quagga mussels attached to moored vessels and dock structures at the Wahweap Marina in Lake Powell. None of the adult mussels were close enough together to mate for successful reproduction. All of the mussels were physically removed from the lake.
The first four mussels were found when a local marine service business noticed the small shells on a boat that had been pulled for maintenance and then notified the park service.
“We really appreciate the report of this finding since it will help in the removal of the adult mussels before they can reproduce,” said Mark Anderson, a Glen Canyon ecologist. “It’s likely that the mussels were introduced via ballast or bilge water from a boat that was not cleaned, drained, or dried.”
Boats, docks, and cables in Wahweap Bay will continue to be assessed by the NPS dive team. The Antelope Point area was inspected beginning in December of 2012 with no mussels discovered.
“If it is an early detection, the mussels may not establish and reproduce,” said Glen Canyon National Recreation Area supervisor Todd Brindle.
“It is important to note that we have not found a reproducing population,” Anderson said. “Prevention is still the most effective way to fight invasive species, so we will continue the boat inspections that are currently in place. Everyone needs to take this as a warning to continue to clean, drain, and dry your boat and equipment after every use.”
The park service published this document explaining the implications:
What was found?
Fourteen widely dispersed adult quagga mussels were found attached to moored houseboats and dock structures. The mussels were alive, but too far apart to successfully reproduce.
Where were they found?
The adult mussels were found at the Wahweap Marina. Surveys were conducted in the Antelope Point area beginning in December, 2012 and no mussels were detected.
How were they found?
Employees of a local marine services business discovered the first four mussels on a single houseboat that had been removed from moorage for annual cleaning and maintenance. They contacted Glen Canyon National Recreation Area staff on March 18th to identify the organisms. NPS staff confirmed they were quagga mussels. Divers discovered the additional mussels as they searched nearby.
Why is this important?
No adult mussels have been found in Lake Powell prior to last week. The mussels appear to have attached and grown on the boats and structures while they were in the lake. The mussels were too far apart, however, to reproduce.
What are the next steps?
Diver surveys will continue in the coming weeks to determine the extent of the number of mussels. When found, mussels are physically removed from the lake to prevent reproduction.
The NPS will continue all of our mussel prevention activities including inspections of boats. Preventing the spread of Quagga mussels and other aquatic invasive species is more important than ever.
If control strategies are not effective, how soon could Lake Powell start experienceing mussel impacts?
Should a mussel population get established and spread, it could be several years before their presence would be obvious. Spreading lake-wide could take considerably longer.
What can the public do to help?
Clean, drain, and dry! The spread of mussels and other aquatic invasive species is preventable. Cooperate with prevention program efforts at Lake Powell and other places where people are trying to protect their waters. Always make sure your vessels and equipment are not causing the problem. Spread the message, not the mussels.
Are boat inpections still required at Lake Powell?
Can boats leaving Lake Powell spread mussels to other waters now?
Not if boaters practice “Clean, Drain, and Dry” and treat their boats and equipment to prevent spreading aquatic species.
What effect will this have on the Colorado River below the dam in Glen and Grand Canyons?
These detections are so low that no effect will occur. If a large infestation of Quagga mussels existed in Lake Powell, large numbers of mussel larvae might travel through the dam. The larvae that survived would seek to attach in low flow areas. It is not known if they could reach high numbers. The Arizona Canal has not yet developed large populations of mussels despite larvae being delivered from the Lower Colorado River.
What has the National Park Service done to stop mussels at Lake Powell?
The NPS has operated a mussel prevention program at Lake Powell since 2000. Over a decade ago, scientists predicted that Lake Powell would be the first lake in the western U.S. to get mussels. The number of high-risk boats coming to the park has increased exponentially in that time. Prior to 2007 and the discovery of mussels in the west, Lake Powell was threatened by about 50 high-risk boats per year from eastern states. In 2011 alone, that number was 17,000. 38 boats with mussels were stopped from launching in 2012, over twice the number in 2011. The increased pressure has required the park to screen boats to determine the highest risks and focus our limited capability where it was needed most. At busy times, as few as 15% of boats may actually get inspected.
How does National Park Service monitoring at Lake powell compare to other mussel monitoring programs?
No other lake on earth is as intensely monitored for mussels as Lake Powell. The NPS processes hundreds of samples each year. The NPS uses 4 early detection methods, including microscopic analysis, automated particle analysis (FlowCAM), Polymerase Chain Reaction (the DNA test), and deployment of artificial substrates to detect early colonization. Sampling occurs lake-wide at routine sites like marinas and the dam; computers are also used to determine random sampling locations throughout the lake. More samples collected are from areas where there are the most boats. Using both routine and random sampling as well as multiple early detection methodologies is expected to increase the chances of very early detection. Control of any invasive species is easiest when caught early. If these current findings represent a population, the best chances have been created for successful control.