Top 100 invasive species

http://conservationinstitute.org/invasivespecies.htm

Expansion of global trade, and increases in human mobility have resulted in unprecedented invasion by nonnative species. These invasive species can produce severe, often irreversible impacts on agriculture, recreation, and our natural resources. Invasive species threaten biodiversity, habitat quality, and ecosystem function. They are the second-most important threat to native species, behind habitat destruction, having contributed to the decline of 42% of U.S. endangered and threatened species. Introduced species also present an ever-increasing threat to food and fiber production. In the United States, the economic costs of non-native species invasions reach billions of dollars each year.

Whether they are called invasive, non-native, alien, exotic, or non-indigenous, introduced species are those that evolved elsewhere and have been purposely or accidentally relocated . While some species have invaded habitats on their own (e.g., migrating wildlife, plants and animals rafting on floating debris), human exploration and colonization have dramatically increased the diversity and scale of invasions by exotic species. Introduced species often find no natural enemies in their new habitat and therefore spread easily and quickly. Invasive species is a problem on land and in the oceans, in deserts, islands, forests, rivers, lakes, farms, almost everywhere.