The annual low-oxygen area off Louisiana's coast is larger than average, but nowhere near the record predicted because of record Mississippi River spring floods.
Nancy Rabalais of the Louisiana Universities Marine Consortium says it's smaller than expected because Tropical Storm Don whipped up winds and waves in the Gulf, mixing oxygen back into lower waters.
Rabalais has studied the so-called "dead zone" since 1985. She reports that it covers about 6,765 square miles of the Gulf of Mexico.
Because it's fed by fertilizer and runoff from across America's heartland, scientists had expected it to cover 8,500 to 9,400 square miles. That would have been about the size of Lake Erie.
The 26-year average through 2010 is 5,200 square miles.