200
Zebra mussels are native to Eastern Europe, but were brought over to the Great Lakes in the ballast water of ships. Once established in the Great Lakes, they caused harm to the ecosystem by outcompeting the other native organisms that eat plankton. Zebra mussels are an example of a/an ________________________________.
A. parasitic species
B. invasive species
C. indictor species
D. threatened species
What is B. invasive species