Answer: The correct answer is B) Native shellfish populations have dramatically decreased as they are outcompeted by the crabs, causing a decrease in biodiversity.
Explanation: Green crabs represent a serious threat to biodiversity in the ocean ecosystem because they are predators that feed with animals that are part of the biodiversity such as clams, mussels, and oysters. As the predators they are, they can dramatically change the ecosystem by affecting the living and reproduction of many species.
