Answer: True
Step-by-step explanation:
A keystone predator is a one which plays a functional role in the community of living beings by feeding the considerably increasing prey population. Hence, maintains a balance in nature.
The european green crab is a invasive species, which acts as a keystone predator it fight with the native crab species for resources like food. Reduces the abundance of marine species specially the mollusks, crustaceans and the sellfish.