CHONBURI: An unusually dense plankton bloom off the eastern coast of Thailand is creating an aquatic "dead zone", threatening the livelihood of local fishermen who farm mussels in the waters.Marine scientists say some areas in the Gulf of Thailand have more than 10 times the normal amount of plankton, turning the water a bright green and killing off marine life."This is the first that I've seen it so bad," said marine scientist Tanuspong Pokavanich. "It is very severe."Plankton blooms happen one or two times a year and typically...