The amount of nitrogen entering the Gulf each spring has increased about 300 percent since the 1960s, mainly due to increased agricultural runoff, Scavia said.
"Yes, the floodwaters really matter, but the fact that there's so much more nitrogen in the system now than there was back in the '60s is the real issue," he said. Scavia's computer model suggests that if today's floods contained the level of nitrogen from the last comparable flood, in 1973, the predicted dead zone would be 5,800 square miles rather than 8,500.
"The growth of these dead zones is an ecological time bomb," Scavia said. "Without determined local, regional and national efforts to control them, we are putting major fisheries at risk." The Gulf of Mexico/Mississippi River Watershed Nutrient Task Force has set the goal of reducing the size of the dead zone to about 1,900 square miles.
In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly 3 million recreational fishers further contributed more than $1 billion to the Gulf economy, taking 22 million fishing trips.
The Gulf hypoxia research team is supported by NOAA's Center for Sponsored Coastal Ocean Research and includes scientists from the University of Michigan, Louisiana State University and the Louisiana Universities Marine Consortium. NOAA has funded investigations and forecast development for the dead zone in the Gulf of Mexico since 1990.
"While there is some uncertainty regarding the size, position and timing of this year's hypoxic zone in the Gulf, the forecast models are in overall agreement that hypoxia will be larger than we have typically seen in recent years," said NOAA Administrator Jane Lubchenco.
The actual size of the 2011 Gulf hypoxic zone will be announced
|Contact: Jim Erickson|
University of Michigan