Live Science: Four years ago, about 100 melon-headed whales mysteriously entered a shallow lagoon system in northwest Madagascar and became stranded. Now scientists say the creatures' demise was likely brought on by sonar used to map the ocean floor for ExxonMobil. Previous research has suggested that sonar can be harmful to marine mammals. The underwater noise can mask the calls of dolphins and whales and scare them away from their feeding grounds. Naval exercises using sonar have been linked to a 2008 stranding...