Feral hogs are also a large problem in the Hawaiian Islands. Last year, DSIL and I were to go on a hog hunt in Maui, but couldn't get our schedules to match. Invasive species are a problem everywhere, to some degree. Some of the areas around the Great Lake areas are under great stress due to ...earthworms! Earthworms are not native to some areas near the Great Lakes, and when a unsuspecting angler would dump his unused earthworms on the lake shore, they do what earthworms do. They eat the organic material on the forest floor, and open up vast areas to erosion, upset the soil composition and mess things up.
On a similar but separate note, Hawaii has banned certain sunscreens because the kill the coral reefs.