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The Nonindigenous Aquatic Species Program (NAS) tracks the status and distribution of introduced aquatic organisms and provides this information in a timely manner for research, management and education.
Nonindigenous species are ranked second only to habitat loss in the factors that threaten native biodiversity, however the geographic distribution of many of these organisms is poorly understood. As new taxa are introduced and the range of those previously established continues to increase, precise tracking of their status and distribution is imperative for decision making and resource management.
There are two programs at the Gainesville Center that compliment each other. The nonindigenous fishes program conducts field and laboratory studies. The other program (NAS) is developing a database on all nonindigenous aquatic species.
Invasive nonindigenous species are important because they threaten native communities, alter habitats, and can have significant economic impacts. In aquatic environments, invasive species can be especially noxious because native species have few options for escaping direct interactions such as predation and competition for habitat and food.
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Realtime Nonindigenous Species Data Displayed with Google Map
 To see the distribution maps in action for seven invasive species, go to:
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African Jewelfish Hemichromis letourneuxi |
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Understanding Everglades Invaders: Ecophysiology of the African Jewelfish Hemichromis letourneuxi. A dozen species of nonindigenous fishes have colonized the wetlands of south Florida. Although some of these species continue to spread geographically, others remain local. Information relating to their biology, ecology, and environmental tolerances has been accumulating, but data gaps remain for several common species. Learn More
 Effects of Hurricanes Katrina and Rita (2005) on populations of nonindigenous Nile tilapia (Oreochromis niloticus) in southern Mississippi. In August 2005, Hurricane Katrina impacted coastal Mississippi with strong winds and an estimated 9-meter (30-foot) storm surge. Hurricane Rita followed less than a month later, and although its impact on coastal Mississippi was much less than that of Katrina, it reflooded much of the coastal ecosystem. Although these storms likely served to disperse Nile tilapia in southern Mississippi, the extent of the spread was unknown. Learn More
 The quagga mussel (Dreissena rostriformis bugensis), a small exotic species from Europe, has been discovered this year in Lake Mead near Boulder City, Nevada. Until this population was detected, quagga mussels had been primarily confined to the Great Lakes Region where they were introduced along with the zebra mussel in the late 1980s. Most likely the quagga mussels were introduced to Lake Mead by a boat that had recently been in infested waters.
Quagga mussels look very similar to zebra mussels. And like the zebra mussel, the quagga mussel has the potential to cause problems for water users and ecological damage to sensitive ecosystems. Even though both species of mussels have been in the United States for approximately twenty years, scientists are just beginning to understand their long-term impacts on aquatic ecosystems. Impacts for water users are more obvious; quagga mussels can clog pipes and restrict water flow.
In an effort to keep resource managers as well as the public informed, USGS is tracking the range expansion of quagga mussels and making this and other information available. Link: Zebra -vs- quagga FAQs and current distribution.
Nonindigenous Aquatic Species Program (NAS): Distribution Records
High resolution images: zebra_quagga1.JPG, zebra_quagga2.JPG
Maps: Compare Distribution Map.
 Schofield, P.J., Williams, J.D., Nico, L.G., Fuller, P., and Thomas, M.R., 2005, Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the United States—A Guide to their Identification, Distribution, and Biology: U.S. Geological Survey Scientific Investigations Report 2005-5041, 103 p.
This guide contains an identification key to the eleven foreign nonindigenous cyprinids, as well as species accounts that include physical characteristics, reproduction, ecology, and distribution in its native habitat and in the United States. Biologists, resource managers and others interested in nonindigenous fishes will find it a useful tool for identifying foreign cyprinids, some of which superficially resemble their native North American counterparts. Currently available online (Click Here), and in Acrobat PDF format: 20 megabyte file. Get Acrobat Reader.
 Nico, L.G., J.D. Williams, and H.L. Jelks. 2005. Black Carp: Biological Synopsis and Risk Assessment of an Introduced Fish. American Fisheries Society Special Publication 32, Bethesda, Maryland. 337 p.
U.S. Geological Survey biologists Nico, Williams, and Jelks recently published a book on the Black Carp (Mylopharyngodon piceus), a fish native to eastern Asia that has been introduced into the USA and is now present in the Mississippi River. The species is a close relative of Grass Carp and individuals commonly grow to well over one-meter long, with a maximum of two meters or more. Black Carp are bottom dwellers with specialized diets consisting largely of snails and mussels, consequently they pose a threat to native mollusks many of which are already endangered. Similar to Bighead Carp and Silver Carp, two other Asian species that have invaded the Mississippi River basin, Black Carp normally make annual migration runs and spawn in large rivers.
A detailed description of the book and information on how to obtain copies can be found on the web site of the publisher, the American Fisheries Society: http://64.224.98.53/publications/catbooks/x51032C.shtml.
 A fish tail: The dog-eating snakehead, Gainesville Sun, Article published Sep 7, 2005, featuring USGS Scientist Walt Courtenay 92kb pdf article
Snakeheads (Pisces, Channidae) - A Biological Synopsis and Risk Assessment (includes download print version)
Snakehead Q & A's (includes download print version)
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U.S. Department of the Interior |
U.S. Geological Survey
