Coming this summer: “The Dead Zone” in the Gulf of Mexico unless a tropical storm hits the area shortly before or during the annual measurement. By definition a “Dead Zone” is too little oxygen to support fish, shellfish and other aquatic life.
The hypoxic zone in the Gulf is likely to be the largest since annual measurements began in 1985, covering 8,561 square miles – about the size of the state of New Jersey, according to scientists from Louisiana State University and the Louisiana Universities Marine Consortium.
Low- and no-oxygen areas in the gulf are measured in cubic miles and water volume. The Gulf dead zone affects nationally important commercial and recreational fisheries and threatens the whole gulf economy. Forecasts are based on nutrient runoff and river stream data from the U.S. Geological Survey. The nutrients are largely nitrogen and phosphorus, much of them from farms in the large river system that feed the gulf.
Since 1995, the Gulf dead zone has averaged 5,960 square miles, an area roughly the size of Connecticut. In 2001 and 2008, state, federal and tribal agencies in the Mississippi River watershed – about 40 percent of the country – set a goal to reduce the size of the Gulf hypoxic zone to an average of 1,950 square miles by 2015.‘“The size of the Gulf dead zone goes up and down depending on that particular year’s weather patterns. But the bottom line is that we will never reach the action plan’s goal of 1,950 square miles until more serious actions are taken to reduce the loss of Midwest fertilizers to the Mississippi River system, regardless of the weather,” Scavia said.
Last year, drought upriver cut runoff so drastically that the Gulf of Mexico dead zone was the fourth-smallest on record, less than 2,900 square miles. Michigan scientists had predicted it would cover just under 1,200 square miles while Louisiana, scientists predicted about 6,200 square miles. Both groups have refined their techniques this year.
Scientists will measure this year’s Gulf dead zone July 21-28, weather permitting. A tropical storm during or within two weeks of that period would reduce its size to as little as 5,344 square miles by mixing oxygen at the surface deep into the water. (NOAA Dead Zone article)