Wednesday, June 22, 2011

Gulf of Mexico Dead Zone

Image credit: NOAA
Major flooding on the Mississippi river predicted to cause largest Gulf of Mexico dead zone ever recorded
NOAA, June 14, 2011The Gulf of Mexico’s hypoxic zone is predicted to be the largest ever recorded due to extreme flooding of the Mississippi River this spring, according to an annual forecast by a team of NOAA-supported scientists from the Louisiana Universities Marine Consortium, Louisiana State University and the University of Michigan. The forecast is based on Mississippi River nutrient inputs compiled annually by the U.S. Geological Survey (USGS).

 Scientists are predicting the area could measure between 8,500 and 9,421 square miles, or an area roughly the size of New Hampshire.  If it does reach those levels it will be the largest since mapping of the Gulf “dead zone” began in 1985. The largest hypoxic zone measured to date occurred in 2002 and encompassed more than 8,400 square miles. 
The average over the past five years is approximately 6,000 square miles of impacted waters, much larger than the 1,900 square miles which is the target goal set by the Gulf of Mexico/Mississippi River Watershed Nutrient Task Force. This collaboration between NOAA, USGS and university scientists facilitates understanding links between activities in the Mississippi River watershed and downstream impacts to the northern Gulf of Mexico. Long-term data sets on nutrient loads and the extent of the hypoxic zone have improved forecast models used by management agencies to understand the nutrient reductions required to reduce the size of the hypoxic zone.

Hypoxia is caused by excessive nutrient pollution, often from human activities such as agriculture that results in too little oxygen to support most marine life in bottom and near-bottom water. The hypoxic zone off the coast of Louisiana and Texas forms each summer and threatens valuable commercial and recreational Gulf fisheries. In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed more than $1 billion to the Gulf economy taking 22 million fishing trips.   (Read full article)