Combating the Proliferation of Harmful Aquatic Hitchhikers

Zebra Mussels Close-Up of a Zebra Mussel

Zebra mussels are an invasive, freshwater species of bivalve mollusks. They get their name from the striped pattern on their shells (although some zebra mussels do not display these patterns) and belong to the same family as clams, oysters, and scallops. Zebra mussels typically live four to five years and are native to freshwater rivers and lakes in Eastern Europe and western Asia. Zebra mussels were first discovered in Lake St. Clair, MI in 1988, and by 1990 had infested all the Great Lakes. Today, the species has spread to 29 states and can be found in many rivers, lakes, and reservoirs across the country.

Zebra mussels are highly adaptable to a wide range of environmental conditions. They are prolific breeders, and each female has the potential to spawn over 1 million eggs a year. The microscopic larvae are free-swimming for the first few weeks of their lives, and are easily picked up and transported long distances by ballast water, recreational boats, fishermen, and even bait buckets. Barge traffic in large, busy rivers and artificial channels has also helped facilitate their dispersal.

Aquatic invasive species such as the zebra mussel present a growing worldwide problem and can adversely affect recreation, economies, and entire ecosystems. Zebra mussels disrupt the food chain and affect water quality. They encrust boats and clog engines, reducing performance and efficiency. Zebra mussels can also clog irrigation, drinking water, and other intake pipes. Zebra mussels attach themselves to native freshwater mussel colonies, essentially smothering and killing them.

Zebra mussels are closely related to the quagga mussel, and have established a presence in Lake Mead, Lake Mohave, and Lake Havasu. At this time, Lake Powell and the upper Colorado River are believed to be free of zebra and quagga mussels, but pose a major threat to these ecosystems if they become established. Conditions in Lake Powell such as water temperature, turbidity, and salinity are ideal for zebra and quagga mussels. In response to this threat, the Glen Canyon National Recreation Area has had a zebra mussel prevention program in place since 1999, and expanded the program in 2007. Some components of the Expanded Zebra Mussel Action Plan include:

  • Preventing the Spread of Zebra Mussels - Boats that have been launched in states with zebra mussel infestations within the last 30 days must be decontaminated before launching in the park.
  • Allowing Visitors to Self-Certify that their Boats are Mussel Free - The NPS has developed a simple system to allow visitors to certify that their boats are zebra and quagga mussel free.
  • Continuing Monitoring Programs - Artificial substrate samplers are deployed across the lake to allow early detection of any infestation.
  • Decontaminating Boats - The park’s concessioners, ARAMARK and Antelope Point Holdings, LLC, have four zebra mussel decontamination stations.
  • Using Educational Outreach and Communications– A “Zap the Zebra Mussel” brochure along with other educational materials will be distributed at locations throughout the park and to businesses in gateway communities.

Once established, zebra mussels are virtually impossible to eradicate. Prevention is really the only viable strategy to combat this invasive species, and education is critical to stop the spread of zebra mussels. Ultimately, the responsibility of combating zebra mussels falls on each of us, and we must do our part to ensure we do not inadvertently aid in the dispersal and establishment of these aquatic hitchhikers.

For more information, please contact NPS_Greenline@nps.gov.