Thursday, June 25, 2009

Large 2009 Gulf Of Mexico 'Dead Zone' Predicted




Mississippi dead zone in 2004. This year's Gulf of Mexico "dead zone" could be one of the largest on record, continuing a decades-long trend that threatens the health of a half-billion-dollar fishery. (Credit: Photo courtesy of NASA/Goddard Space Flight Center Scientific Visualization Studio)




The official size of the 2009 hypoxic zone will be announced following a NOAA-supported monitoring survey led by the Louisiana Universities Marine Consortium on July 18-26. In addition, NOAA's Southeast Area Monitoring and Assessment Program's (SEAMAP) is currently providing near real-time data on the hypoxic zone during a five-week summer fish survey in the northern Gulf of Mexico.






"The growth of these dead zones is an ecological time bomb," said Scavia, a professor at the U-M School of Natural Resources and Environment and director of the U-M Graham Environmental Sustainability Institute.
"Without determined local, regional and national efforts to control them, we are putting major fisheries at risk," said Scavia, who also produces annual dead-zone forecasts for the Chesapeake Bay.


The Gulf dead zone forms each spring and summer off the Louisiana and Texas coast when oxygen levels drop too low to support most life in bottom and near-bottom waters


Additional flooding of the Mississippi since May could result in a dead zone that exceeds the upper limit of the forecast, the scientists said.
"The high water-volume flows, coupled with nearly triple the nitrogen concentrations in these rivers over the past 50 years from human activities, has led to a dramatic increase in the size of the dead zone," said Gene Turner, a lead forecast modeler at Louisiana State University
.


Farmland runoff containing fertilizers and livestock waste—some of it from as far away as the Corn Belt—is the main source of the nitrogen and phosphorus that cause the Gulf of Mexico dead zone.

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