Module 3 • Ecology: Blue Planet
Teacher Notes 3-3b
Invasive Species
Invasive species are a worldwide problem. Animals and plants introduced by human activity to
habitats outside their natural range can displace native species, often with adverse effects on local
ecosystems (Kappel, 2005). Once established, invasive species can be nearly impossible to eliminate.
Over 80 percent of marine eco-regions worldwide have been affected by invasive species. There are
two primary vectors globally for introduction of marine invasive species: international shipping and
aquaculture (Molnar et al., 2008). Marine organisms are carried in the ballast water of large ships and
can attach themselves to the outer hulls of those ships, only to be released in distant ports. The FAO
Database on Introductions of Aquatic Species indicates that aquaculture is the major reason for the
introduction of non-native fish species to different countries.