While the Deepwater Horizon oil gusher continues to mire the Gulf of Mexico, another threat could be growing below the oil slicked surface. This is the “Dead Zone”. Currently the most well known dead zone is about 8,500 square miles in size and lies in the Gulf of Mexico, where the Mississippi River dumps high nutrient runoff from its vast drainage basin, which includes the heart of the U.S. agriculture business from the Midwest. This is equivalent to a dead zone the size of New Jersey. Dead zones are hypoxic (low oxygen) areas in the world’s oceans, the observed incidences of which have been increasing since oceanographers began noting them in the 1970s.