New and Bigger Dead Zones Appearing Worldwide, Study Says

A new survey published in Science counts more than 400 “dead zones” in coastal waters worldwide, the result of agricultural runoff draining oxygen from the water and suffocating marine life. Ranging from massive dead zones in the Gulf of Mexico and the Baltic Sea to small, cyclical ones in estuaries and rivers, these zones collectively cover about 95,000 square miles. Dead zones occur when fertilizers washed into waterways fuel algal blooms, which then decay in a process that sucks oxygen from the water, making it unlivable for other creatures. The amount of biomass destroyed by a dead zone in the Chesapeake Bay, the scientist who led the study estimates, could feed fully half of all the crabs harvested each year. New dead zones have appeared in the Florida Keys, Puget Sound, and estuaries in the Carolinas, the study found; worldwide, only 4 percent of dead zones are improving.