Invasion

INVASION

Example Species

Sea Lamprey

Zebra Mussel

The Nonindigenous Aquatic Nuisance Prevention and Control Act defines a nuisance or “invasive” species to be “a nonindigenous species that threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural, aquacultural, or recreational activities dependent on such waters.”

Nonindigenous species are introduced or transported into new environments by various vectors. In order to become established, the organisms must then find an ecological niche, thrive, and reproduce. Many factors determine whether the environment is habitable for a particular species, including the physical properties of the water (temperature, salinity, oxygen content, and light), the availability of food, the reproductive strategy of the species, and the presence or absence of predators and competitors. (2). Because environments change over time, a “window of opportunity” may permit a species to establish itself, despite previously unfavorable conditions. Global climate change is increasing the number of established nonindigenous species by affecting water temperatures and altering the geographic range in which certain species may survive. (3)

USACE

Kolar and Lodge (2002)

Several characteristics may make a species more likely to become invasive. Researchers have suggested that these characteristics include:
1. Abundant & widely distributed in original range
2. Wide environmental tolerance
3. High genetic variability
4. Short generation time
5. Rapid growth
6. Early sexual maturity
7. High reproductive capacity
8. Broad diet (opportunistic feeding)
9. Gregariousness
10.Natural mechanisms of rapid dispersal
11. Commensal with human activity (e.g., ship ballast-water transport)
(4)

Once a species gains a foothold, it can spread. The spreading of introduced species is a particular problem in aquatic environments such as the Great Lakes because of the continuity of the habitat. Waves, currents, and other circulations propagate the invasion by carrying the individuals and their larvae, eggs, and spores to other locations. A system of locks and canals connect the Great Lakes to each other and to other waterways, including major rivers such as the St. Lawrence, Hudson, Ohio, and Mississippi. In this way, invasive species can quickly become a basin-wide problem.

Introduction Invasion Vectors Ballast Water Ballast Water Management Ecological Effects Economic Effects Example Species Sea Lamprey Zebra Mussel Round Goby Asian Carp Laws and Policies What Can be Done? References Biology 217 Home Duke Home	The Nonindigenous Aquatic Nuisance Prevention and Control Act defines a nuisance or “invasive” species to be “a nonindigenous species that threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural, aquacultural, or recreational activities dependent on such waters.” Nonindigenous species are introduced or transported into new environments by various vectors. In order to become established, the organisms must then find an ecological niche, thrive, and reproduce. Many factors determine whether the environment is habitable for a particular species, including the physical properties of the water (temperature, salinity, oxygen content, and light), the availability of food, the reproductive strategy of the species, and the presence or absence of predators and competitors. (2). Because environments change over time, a “window of opportunity” may permit a species to establish itself, despite previously unfavorable conditions. Global climate change is increasing the number of established nonindigenous species by affecting water temperatures and altering the geographic range in which certain species may survive. (3)
	USACE	Kolar and Lodge (2002)
		Several characteristics may make a species more likely to become invasive. Researchers have suggested that these characteristics include: 1. Abundant & widely distributed in original range 2. Wide environmental tolerance 3. High genetic variability 4. Short generation time 5. Rapid growth 6. Early sexual maturity 7. High reproductive capacity 8. Broad diet (opportunistic feeding) 9. Gregariousness 10.Natural mechanisms of rapid dispersal 11. Commensal with human activity (e.g., ship ballast-water transport) (4)
	Once a species gains a foothold, it can spread. The spreading of introduced species is a particular problem in aquatic environments such as the Great Lakes because of the continuity of the habitat. Waves, currents, and other circulations propagate the invasion by carrying the individuals and their larvae, eggs, and spores to other locations. A system of locks and canals connect the Great Lakes to each other and to other waterways, including major rivers such as the St. Lawrence, Hudson, Ohio, and Mississippi. In this way, invasive species can quickly become a basin-wide problem.