How Alien Species Wipe Out Natives

Below I discuss three major impacts of alien species with examples

Predation - The introduction of a predator that organisms have not previously been exposed to can profoundly affect food chains. Most obvious in the Great Lakes-St. Lawrence system was the introduction of the sea lamprey (Petromyzon marinus) which, combined with overharvesting, caused lake trout to be wiped out from the upper Great Lakes in the mid-1900s. Though, right now, lake trout is making recovery with conservation efforts by humans.

Disease and Parasites - Pest species accidentally introduced to an area provide the most dramatic example of the damage that exotics can pose to native species. For instance, an exotic beetle was the vector for Dutch elm disease, which has devastated elm trees in North America.

Accidental Species Introduction - Species introductions can occur accidentally, when organisms “hitchhike” into new systems on other animals or objects. For instance, zebra mussels are thought to have been brought into the Great Lakes in the ballast water of tankers that traveled up the St. Lawrence Seaway.