WALPOLE, Maine (AP) — With their thick, hard shells, oysters may appear well protected, but a lot can go wrong before they end up in markets and restaurants. Greenhouse gas emissions blamed for global warming also are making the ocean more acidic, which can interfere with the ability of shellfish like oysters to develop their shells. Bill Mook runs an oyster hatchery in Walpole, Maine.Read more on NewsOK.com