Predicting "larger than average" Gulf of Mexico dead zone

Terra Daily: The northern Gulf of Mexico hypoxic zone, an underwater area with little or no oxygen known commonly as the "dead zone," could be larger than the recent average, according to a forecast by a team of NOAA-supported scientists from the Louisiana Universities Marine Consortium, Louisiana State University, and the University of Michigan.

Scientists are predicting the area could measure between 6,500 and 7,800 square miles, or an area roughly the size of the state of New Jersey. The average of the past five years is approximately 6,000 square miles. It is the goal of a federal state task force to reduce it to 1,900 square miles. The largest dead zone on record, 8,484 square miles, occurred in 2002.

This forecast is based on Mississippi River nutrient flows compiled annually by the U.S. Geological Survey. Dead zones off the coast of Louisiana and Texas are caused by nutrient runoff, principally from agricultural activity, which stimulates an overgrowth of algae that sinks, decomposes, and consumes most of the life-giving oxygen supply in the water.

It is unclear what impact, if any, the BP Deepwater Horizon oil spill will have on the size of the dead zone. "The oil spill could enhance the size of the hypoxic zone through the microbial breakdown of oil, which consumes oxygen, but the oil could also limit the growth of the hypoxia-fueling algae," said R. Eugene Turner, Ph.D., professor of oceanography at Louisiana State University. "It is clear, however, that the combination of the hypoxic zone and the oil spill is not good for local fisheries."...

The delta of the Atchafalaya River on the Gulf of Mexico. View is upriver to the northwest. US Army Corps of Engineers