The dead zone off the coasts of Louisiana and Texas is nearly the size of Connecticut and much larger than federal researchers had predicted earlier this year, according to a new survey.
An annual weeklong cruise led by researchers with the Louisiana Universities Marine Consortium found an area of low-oxygen measuring 4,564 square miles and extending from the Mississippi River to the Texas border. On average, the dead zone has measured about 4,800 square miles since 1985.
The dead zone, also known as hypoxia, forms each spring and summer as fresh water enters the Gulf of Mexico and causes large algae blooms. The algae die and sink to the bottom of the Gulf, where they decompose, using up oxygen in the deeper, saltier water. Fish avoid the low-oxygen water, and bottom-living organisms are killed.
The dead zone could in the long-term affect the overall health
of the Gulf's marine species, said Nancy Rabalais, a leading
hypoxia researcher with the Louisiana Universities Marine
Consortium. She said researchers are studying how the dead zone
affects the growth and reproduction of marine species.
The dead zone could grow much larger this year — perhaps as
large as 6,200 square miles — if major storms do not stir up the
Gulf in the coming months, Rabalais said.
Officials are looking for ways to cut down on the amount of fertilizer and pollution in watersheds that flow into the Mississippi and end up in the Gulf.
The zone's size varies year to year. At 5,800 square miles, last
year's was bigger than Connecticut. The record of 8,500 — about the size of Israel and a bit smaller than New Jersey — was in 2002.
Earlier this month, the National Oceanic and Atmospheric Administration had predicted a much smaller dead zone because the Mississippi and Atchafalaya rivers were carrying much less nitrogen and other nutrients than usual. NOAA predicted that about 1,500 square miles of Gulf waterbottom would likely be without oxygen this year.