How has biodiversity been affected in areas where green crabs have been introduced?

a. additional predators have migrated into the area to feed on the crabs, causing an increase in predator diversity.

b. native shellfish populations have dramatically decreased as they are outcompeted by the crabs, causing a decrease in biodiversity.

c. the amount of predation on crabs by seabirds has gone up, but biodiversity has not been affected.

d. the overall number of crab species has dramatically increased, increasing overall biodiversity.

The correct answer is B) Native shellfish populations have dramatically decreased as they are outcompeted by the crabs, causing a decrease in biodiversity.

Biodiversity has been affected in areas where green crabs have been introduced in that native shellfish populations have dramatically decreased as they are outcompeted by the crabs, causing a decrease in biodiversity.

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.  

option c is the correct answer.