The Gulf Coast Dead Zone

You’ve heard how hurricanes, oil spills, and industrial development are affecting the Gulf of Mexico, but have you heard about the “hypoxic” or low oxygen dead zones?

The National Oceanic and Atmospheric Administration is predicting that a massive dead zone the size of New Jersey (8,561 square miles) will plague the northern Gulf of Mexico this summer, citing a combination of heavy rainfall, flooding, drought, and human activity in the Midwest as the primary culprits.

Data from the U.S. Geological Survey finds that nonpoint sources of nitrogen and phosphorus based fertilizers, animal wastes, sewage, and other nutrient-rich pollutants (i.e., lawn fertilizers) from six major tributaries along the Mississippi River watershed are flowing toward the Gulf at an alarming rate, resulting in the growth of algae blooms that deplete the waters of oxygen as they die and decompose, thereby creating a biological desert.

Runoff fueling the Gulf of Mexico dead zone
Courtesy Donald Scavia / University of Michigan

The USGS estimates 153,000 metric tons of nutrients flowed down the watershed to the northern Gulf of Mexico, an increase of 94,900 metric tons over last year’s 58,100 metric tons, when the region was suffering through drought. This is 16 percent above the 34 year average nutrient load.

The dead zone in the Gulf of Mexico will not only affect nationally important commercial and recreational fisheries of pogie, redfish, shrimp, crabs, oysters, and fresh water eels, but will significantly threaten the region’s economy; still reeling in the aftermath of the BP Deepwater Horizon Oil Catastrophe.

Courtesy P. J. Hahn/Coastal Zone Management Department

Ironically, NOAA models suggest that the size of the dead zone could be reduced by a large storm or hurricane, which would help churn up the water, thus reducing the hypoxic dead zone to roughly the size of Connecticut (5,344 square miles).

Which in and of itself is pretty big.