10. (D.) None of these species are native to New England. (return)

9. (D.) There were 30 million in this estuary alone. (return)

8. (A.) The goby eats the fry and eggs of other fish. Although it does also eat zebra mussels, this is not considered a problem because the zebra mussel is another non-native and problem causing species. (return)

7. (B.) Dermo was introduced with American oysters, which it parisitizes. (return)

6. (D.) Non-native species can cause economic harm by damaging structures or competing with commercially valuable organisms. Because they often have no natural predators, they can multiply unhindered, causing many problems such as out-competing native species. (return)

5. (B.) Ships entering the Great Lakes must have exchanged ballast water mid ocean or undertaken another pre-approved method of killing organisms in the ballast water. (return)

4. (A.) This requirement was made in July of 1999. (return)

3. (A.) Hemigrapsus is thought to have been introduced via ballast water to New Jersey, where it spread to the rest of New England in the last two decades of the 20th century. (return)

2. (B.) Ballast is taken on to compensate for a lack of cargo. (return)

1. (C.) Ships carry ballast water to provide stability. (return)