Lake Granby samples test positive for invasive quagga mussel larvae
July 15, 2008
DNA testing recently confirmed the presence of quagga mussel larvae ” the adult form of which is a disruptive, invasive species ” in Lake Granby.
Samples were taken close to Granby Dam in early July. Veligers, or the larval stage of the quagga mussel, were initially identified by microscopic analysis. The finding was followed by DNA testing, and an additional independent lab confirmed the presence of quagga mussel DNA in the samples, according the Colorado Division of Wildlife (DOW).
Quagga mussels are similar to the zebra mussels that were found last fall in Pueblo Reservoir.
Quagga and zebra mussels are small barnacle-like mollusks with dark and light colored stripes that smother aquatic organisms such as crayfish and native mussels and out-compete them for food and aquatic habitat.
They damage equipment by attaching to boat motors or hard surfaces and clog water-treatment facilities.
The keeled-edge quagga mussels are more cold tolerant than the well-known zebra mussel and have been found in California, Nevada and Arizona, including Lake Mead.
The unique arrangement of the Colorado-Big Thompson Project ” with the Colorado River flowing out of Lake Granby, and reservoirs Lake Granby and Shadow Mountain interconnected with natural Grand Lake ” compounds the problem.
Water flows from Lake Granby through Shadow Mountain into Grand Lake to a 13-mile tunnel that deposits water on the East Slope. Boaters have the ability to travel from Shadow Mountain Reservoir to Grand Lake.
“We don’t know at this point whether they’ll spread from lake to lake,” said DOW spokesman Tyler Baskfield, adding that calcium levels of lakes and natural barriers can play a roll in reducing the mussels’ ability to spread.
Officials are not yet saying what might be done to prevent the scenario of the mussel spreading to connected lakes and rivers.
“There are still a lot of questions that need to be answered,” Baskfield said. “Keep in mind, they have yet to find an adult mussel.”
The Lake Granby larvae were detected during a state and federal initiative that took place to gather more information about the presence of invasive mussels in Colorado, according to the DOW. Lake Granby is the highest-elevation water body in which the mollusks have been found.
Results of the tests were made known to lake stakeholders at the end of last week.
Officials say the discovery steps up the need to develop a protocol for each of the Colorado-Big Thompson reservoirs and the lake, which are overseen by the DOW, the U.S. Bureau of Reclamation, the U.S. Forest Service, and the Northern Colorado Water Conservancy District.
DOW officials say the agencies are working together as they “monitor” the lakes and collect scientific information.
In the meantime, public awareness and participation are the best weapons to contain these invasive species, officials say.
The larvae most likely entered the lake by way of hitching a ride. Spread of such invaders usually happens when a boat coming from an infected lake launches into another lake.
Boaters at Lake Granby especially are reminded to make sure they “Clean, Drain, and Dry” their boats when they leave the lake.
The DOW advises that all boaters should be prepared to have their boats inspected prior to launching at some of the Colorado water bodies.
Check with the managing entity to see what boating regulations are in place and receive updates on local conditions.
Quagga and zebra mussels spread from Eurasia to the Northeast and Great Lakes in contaminated ballast water of ships, on anchors and anchor lines. They quickly spread to the Mississippi River, its tributaries and inland lakes and have now established a presence in the West.
” Tonya Bina can be reached at 887-3334 ext. 19603 or e-mail email@example.com.