Eco Invasion

Each ecosystem has its own balance of plants and animals established over long periods of time. When non-native species from other ecosystems are introduced this can devastate these environments by reducing biodiversity, altering genetic diversity and transmitting exotic diseases to the species already in the ecosystem. Hot zones for non-indigenous species have occurred in places such as Florida where aquatic habitats have been drained or modified to make way for development. Aquarium releases, government bio-control, planting fish for sport fishing and international trade also contribute the rise of invasive species. The most invasive species in the world is quite possibly humans. Tourism and trade brings ships, jets, supplies, people and alien species to every corner of the world faster and more frequently then would occur in nature.

http://www.eco-pros.com/invasive_non-native_species.htm