National Geographic: More than 40 square miles (104 square kilometers) of coral reefs-some of the most biodiverse on Earth-have been destroyed by giant clam poaching in the South China Sea, according to a new analysis of satellite imagery. The poachers use boat propellers to loosen the valuable bivalves, which can weigh up to 500 pounds (227 kilograms) and are a luxury item in China. Carving up a reef leaves it barren of life. And because reefs in the region are often interconnected, the damage in one place can have...