Aquatic Invasive Species (AIS)

Aquatic Invasive Species (AIS), also known as aquatic nuisance species, are nonindigneous invasive species that negatively impact aquatic ecosystems and human services. AIS have impacted nearly every aquatic ecosystem in the United States, posing risks to native species within those ecosystems, as well as human and wildlife health. AIS can be plants, such as Eurasian watermilfoil, animals, such as zebra mussels, nonnative fishes, or microorganisms, such as the parasites that cause whirling disease. Once introduced into new habitats these organisms disturb native species through competition, predation, displacement, hybridization, spread of disease and parasites, and can ultimately cause extinction of many valued organisms. AIS can also affect humans by causing adverse impacts to commercial, agricultural, aquacultural, and recreational activities that depend on water resources for viability.

AIS are introduced to habitats though both natural and human-caused mechanisms. In many waters, fisheries management programs have transplanted nonnative sportfish to provide recreational opportunities. Additionally, many other aquatic organisms have been transported via ballast water in ships (e.g., zebra mussel), aquarium releases, and illegal translocations. Regardless of the cause of species introductions, the establishment and proliferation of AIS often results in the decline of native organisms and the modification of aquatic communities. Over the past 50 years the rate of AIS introduction has dramatically increased. Once introduced, populations often grow quickly and spread rapidly due to lack of natural controls. Once established, they can displace native species, clog waterways, impact municipal and industrial irrigation and power systems, degrade ecosystems, reduce or threaten recreational and commercial fishing opportunities, and can cause wildlife and public health problems.

Freshwater fish are likely the most threatened group of vertebrates in North America, other than amphibians. In fact, exotic species introductions were a factor in 68% of fish extinctions in North America. The Northern Rocky Mountains are considered a stronghold for threatened salmonid species, such as bull trout, westslope cutthroat trout, and Yellowstone cutthroat trout, whose populations have dramatically declined over the past 100 years due to habitat loss and introduction and invasion of nonnative salmonids such as lake trout and rainbow trout. Consequently, many remaining populations are restricted to small, fragmented headwater habitats in protected areas, where their long-term sustainability is uncertain do to risk of invasion by nonnative salmonids from downstream sources.

Research at NOROCK plays an important role in efforts to combat AIS throughout the western United States through early detection and assessment of newly established invaders; monitoring of invading populations; improving understanding of the ecology of invaders and factors in the resistance of habitats to invasion; and development and testing of prevention, management, and control methods.

Current Projects

• Crown of the Continent Ecosystem (Muhlfeld)
• Ecotoxicology (Gross)
• Landscape Scale Impacts on Native Trout (Gresswell)

Upcoming Symposia

None

Publications & Reports

Gresswell, Robert E. 2009. Scientific review panel evaluation of the National Park Service lake trout suppression program in Yellowstone Lake, August 25th–29th. Final Report. USGS Northern Rocky Mountain Science Center, Bozeman, Montana. YCR–2009–05.

Additional Resources

Greater Yellowstone Area (GYA): Clean Inspect Dry website