Several hurricanes released exotic animals in larger numbers over the years. These animals arnt "native" to the area and have no natural predators or other means of control. They breed and reproduce unrestricted. A animal that has many little ones each cycle but has a low rate of survival doesnt populate to quickly. Rabbits are a good example. An animal with the high reproduction and high survival rate quickly takes over an area taking food and cover from indigenous species driving them out.
On the great lakes the zebra muscle was introduced thru ships ballast water taking over the system fouling intakes and other structures, taking food from the perch crappie and other species. There are other species in the lakes now like this.