The Gulf of Mexico's dead zone — an underwater area with little or no oxygen that has plagued Gulf waters for many years — will be larger than usual this year, scientists say.
Dead zones are a concern because they can threaten valuable commercial and recreational Gulf fisheries — an even bigger worry with the massive oil spill also threatening Gulf waters.
Scientists are predicting that the area of this dead zone could measure between 6,500 and 7,800 square miles (17,000 to 20,200 square kilometers), or an area roughly the size of the state of New Jersey.
The average of the past five years is about 6,000 square miles (15,500 square km). The largest dead zone on record, 8,484 square miles (21,973 square km), occurred in 2002.
The Gulf's dead zone is mostly caused by the runoff of nutrients, particularly from fertilizers. These extra nutrients stimulate 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, also called a hypoxic 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, an oceanographer at Louisiana State University in Baton Rouge. "It is clear, however, that the combination of the hypoxic zone and the oil spill is not good for local fisheries."
The prediction of the dead zone's size is made with computer models and is an annual requirement of the Gulf of Mexico Hypoxia Task Force Action Plan, whose goal it is to reduce the dead zone's size to just 1,900 square miles (4,900 square km).
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