Zebra Mussel Invasion

The passage suggests that people will not be able to stop the invasion of the zebra mussel in North America, and the invasion will result in a real threat to freshwater fish. However, the professor in the lecture does not agree with the opinion from the passage.

First, the passage suggests the people cannot stop the invasion because the past history showed that ship would help spread out the zebra mussel. However, the professor pointed out that this might be true in the past, but now people have the new way to stop the ship from helping spread the zebra mussel. For example, in the past, people used fresh water as ballast water, which contained zebra mussel. Since zebra mussel could survive in the fresh water, they would spread out in the other