Drought's silver lining: Gulf "dead zone" is smaller
NOAA-supported scientists have found the size of this year’s Gulf of Mexico oxygen-free ‘dead zone’ to be the fourth smallest since mapping of the annual hypoxic, or oxygen-free area began in 1985. Measuring approximately 2,889 square miles, the 2012 area is slightly larger than Delaware.
The survey also found a patchy distribution of hypoxia across the Gulf differing from any previously recorded. This is in stark contrast to last year, when flood conditions, carrying large amounts of nutrients, resulted in a dead zone measuring 6,770 square miles, an area of the state of New Jersey. The last time the dead zone was this small was in 2000 when it measured 1,696 square miles, an area slightly smaller than Delaware.
“The smaller area was expected because of drought conditions and the fact that nutrient output into the Gulf this spring approached near the 80-year record low,” said Nancy Rabalais, Ph.D., executive director of the Louisiana Universities Marine Consortium (LUMCON) who led the survey cruise. “What wasn’t expected was how the scattered distribution of hypoxia areas differed from any others documented in the past. Confirmed, however, is the strong relationship between the size of the hypoxic zone and the amount of fresh water and nutrients carried to the Gulf by the Mississippi River.”