Invasive Mussels

The Colorado Division of Wildlife confirmed the detection of quagga mussel larvae in Lake Granby this month.  This follows the discovery of zebra mussels in Pueblo Reservoir last fall.  The quagga and zebra mussel are aquatic nuisance species that have already caused millions of dollars in damages in the Great Lakes region, and the monetary and ecological damages are rising across the nation.  It has been estimated that management and control of the mussels costs $1 billion annually.

 

Quagga and zebra mussels spread from Eurasia to the Northeast and Great Lakes in contaminated ballast water of boats or possibly on anchors and anchor lines.  They quickly spread to the Mississippi River, its tributaries and inland lakes.  The quagga mussel has also been detected in the Southwest and Lake Mead.  With the discovery of the mussels in Colorado, it now appears that the invasive species have spread across the entire continental United States. 

 

The mussels are freshwater bivalve mollusks that grow to be about an inch long.  The species are filter feeders and can filter more than one liter of water per day.  They are also extremely prolific, and the females can release more than 100,000 eggs per year.  The adults attach to hard surfaces with byssal threads, typically forming dense clusters.  The accumulation of the mussels have been known to sink a recreational boat dock from the weight of the attached mussels.

 

The mussels cause industrial and raw water fouling, impacting municipal water supplies, hydroelectric stations, and cooling processes at traditional power plants.  They can cause a decrease in recreation and tourism, can disrupt irrigation supplies for agricultural uses, and can cause environmental damage, such as habitat alteration, food web disruption, and impacts to native species.  Health issues can include bioaccumulation of heavy metals and other contaminants, and the sharp shells can cut hands and feet. 

The control of the mussels is extremely challenging.  Pasts methods to control the mussels have proved to be largely ineffective.  Measures employed include chemical molluscides, dewatering/dessication, acoustical vibration, electrical current, copper and zinc coatings, carbon dioxide injection, and ultraviolet light.  Research is being performed that is looking at the veliger stage of the larvae, as this appears to the be the most susceptible life stage of the mussel.   Adult mussels can live out of water for up to 27 days, and the mussels can go dormant to stop filtering water when chemicals are present.  Prevention of the spread of the mussels has been the only control method of controlling the spread, but is not fully effective, as shown by the appearance of the mussels in Colorado.   If boats or equipment come in contact with water bodies containing the mussels, the boats and equipment should be thoroughly cleaned and inspected for the mussels prior to entering other waters.

 

Why is the discovery of quagga mussel larvae in Lake Granby so alarming?  Lake Granby is part of the Colorado-Big Thompson Project, which, according to the Bureau of Reclamation, is one of the largest and most complex natural resource developments they have undertaken.  Lake Granby is west of the continental divide and is part of a series of lakes and reservoirs that supply water east and west of the divide.  A network of pipelines, pump stations, and canals divert water to the front range, supplying domestic and agricultural water to various communities, including Boulder, Longmont, Loveland, and Fort Collins.  Thus, spread of the mussels to Eastern and Western Colorado is possible.