As the world’s oceans get more acidic, Chesapeake Bay oysters could be at risk.

A more acidic bay could make it more difficult for mollusks, such as oysters, to build their shells through a process called calcification. But it could help crustaceans, such as blue crabs, build their shells more quickly, said Justin Ries, a professor at the Marine Science Center at Northeastern University in Boston.

This could disrupt the evolutionary balance of the two, Ries said, because blue crabs prey on oysters.