A survey of marine life in the Gulf of Mexico has found the world’s second-largest “dead zone” ballooning out from the mouth of the Mississippi River and covering an expanse of ocean roughly equal in size to the state of Connecticut.
Scientists for the National Oceanic and Atmospheric Administration measured the dead zone, an expanse of asphyxiating water marked by unusually low oxygen levels and marine life, at roughly 5,052 square miles. Scientists trace the dead zone to nutrient runoffs from farmlands upriver. The nutrients stimulate algae growth, creating massive algae blooms that sink, decompose and consume oxygen that is vital to the surrounding marine life.
“The Dead Zone off the Louisiana coast is the second largest human-caused coastal hypoxic area in the global ocean and stretches from the mouth of the Mississippi River into Texas waters and less often, but increasingly more frequent, east of the Mississippi River,” wrote the study’s author Nancy Rabalais of the Louisiana Universities Marine Consortium (LUMCON). The largest dead zone is thought to be in the Baltic Sea, in Scandinavia.
NOAA scientists note that this year’s dead zone is smaller than the one recorded last year, but still well above the federal target of 1,900 square miles.