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 repercussions elsewhere.

Another 22 square miles (58 square kilometers) of reef have been destroyed by island-building activities, largely by China to solidify its presence, according to the analyis, which was presented at the South