Why Are Exotic Species a Problem?
Today, “exotics”-the term for organisms that have been introduced into areas where they are not native-are considered to be among the most severe, worldwide agents of habitat alteration and degradation. They are a major cause in the continuing loss of biological diversity throughout the world. They have caused extinction of some native species. Exotic species can be thought of as “biological pollutants.” Moving plants or animals, accidentally or intentionally, from one habitat into another where they have never been before is risky business. In the absence of predators, parasites, pathogens, and competitors from their native habitat, species introduced under favorable conditions will often overrun their new home and crowd out important native species. Once established, exotics can rarely be eliminated.
