Habitats: Invaders may alter habitat by eliminating vegetation or changing water quality.
Parasites and Disease: Bacteria, viruses, and parasites introduced with exotic species represent a threat to native organisms.
Food Chain Alteration: The feeding activity of exotics can alter the availability of food resources for native species.
Loss of endemic species: Competition for food and/or space may result in the elimination of related species occupying the same niche. Predation on a native species by exotics is also a problem.
Hybridization: Exotic species may be reproduce with native populations, resulting in hybrids and the ultimate loss of the native species of native species.