Answer:
The zebra mussel is found in freshwater lakes and rivers of the Balkans, Poland, and the former Soviet Union. It was first found in the United States in Lake St. Claire, off of the eastern shore of the state of Michigan.
Biologists think the zebra mussel was picked up in a freshwater European port in the ballast water of a ship, and was later released into the water on the Canadian side of Lake St. Clair. The zebra mussel was not intentionally transported into its new ecosystem.
The zebra mussel is small, free-swimming, and easily spread by water currents, and can attach to almost any hard surface.
The zebra mussel affects an ecosystem's food web both positively and negatively. The positive effects include serving as a food source to many native fish, birds, and other animals. The negative effects include interfering with other organisms' feeding, growth, movement, respiration, and reproduction.
