Gulf's 'dead zone' much smaller than predicted (w/ Video)

Jul 25, 2009

NOAA-supported scientists, led by Nancy Rabalais, Ph.D., from the Louisiana Universities Marine Consortium (LUMCON), found the size of this year's Gulf of Mexico dead zone to be smaller than forecasted, measuring 3,000 square miles. However the dead zone, which is usually limited to water just above the sea floor, was severe where it did occur, extending closer to the water surface then in most years.

Earlier this summer, NOAA-sponsored forecast models developed by R. Eugene Turner, Ph. D. of Louisiana State University and Donald Scavia, Ph.D. of the University of Michigan, predicted a larger than normal dead zone area of between 7,450 - 8,456 square miles. The forecast was driven primarily by the high nitrate loads and high freshwater flows from the Mississippi and Atchafalaya rivers in spring 2009 as measured by the U.S. Geological Survey.

Rabalais believes the smaller than expected dead zone is due to unusual weather patterns that re-oxygenated the waters, among other factors.

This video is not supported by your browser at this time.
Hypoxic zones are areas in the ocean of such low oxygen concentration that animal life suffocates and dies, and as a result are sometimes called "dead zones." One of the largest dead zones forms in the Gulf of Mexico every spring. This data visualization discusses the causes of hypoxia in the Gulf of Mexico. Copyright: National Oceanic and Atmospheric Administration (NOAA)

"The winds and waves were high in the area to the west of the Atchafalaya River delta and likely mixed oxygen into these shallower waters prior to the cruise, thus reducing the area of the zone in that region," said Rabalais. "The variability we see within each summer highlights the continuing need for multiple surveys to measure the size of the dead zone in a more systematic fashion."

"The results of the 2009 cruise at first glance are hopeful, but the smaller than expected area of hypoxia appears to be related to short-term weather patterns before measurements were taken, not a reduction in the underlying cause, excessive nutrient runoff." said Robert Magnien, PhD., director of NOAA's Center for Sponsored Coastal Ocean Research. "The smaller area measured by this one cruise, therefore, does not represent a trend and in no way diminishes the need for a harder look at efforts to reduce nutrient runoff."

The average size of the dead zone over the past five years, including this cruise, is now 6,000 square miles. The interagency Gulf of Mexico/Mississippi River Watershed Nutrient Task Force has a goal to reduce or make significant progress toward reducing this dead zone average to 2,000 square miles or less by 2015. The Task Force uses a five year average due to relatively high interannual variability.

The dead zone is fueled by nutrient runoff, principally from agricultural activity, which stimulates an overgrowth of algae that sinks, decomposes, and consumes most of the life-giving oxygen supply in the water. The Gulf of Mexico dead zone is of particular concern because it threatens valuable commercial and recreational Gulf fisheries that generate about $2.8 billion annually.

The models used to forecast the area of the dead zone are constructed for understanding the important underlying causes to inform long-term management decisions, but they do not include short-term variability due to weather patterns.

Prior to the LUMCON cruise, NOAA's Southeast Monitoring and Assessment Program (SEAMAP) found a similar sized dead zone during its annual five-week summer fish survey.

Source: NOAA

Explore further: New paper calls for more carbon capture and storage research

add to favorites email to friend print save as pdf

Related Stories

Researchers predict large 2009 Gulf of Mexico 'dead zone'

Jun 18, 2009

University of Michigan aquatic ecologist Donald Scavia and his colleagues say 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 ...

Gulf of Mexico dead zone to be studied by marine scientists

Oct 24, 2007

University of Texas at Austin marine scientists have been awarded $781,000 by the National Oceanic and Atmospheric Association (NOAA) to better understand how nutrient pollution from the Mississippi River affects the large ...

Researchers confirm dead zone off Texas coast since 1985

Apr 02, 2008

Researchers at Texas A&M University have confirmed for the first time that a “dead zone” has existed off the Texas coast for at least the past 23 years and will likely remain there, causing potential harmful effects ...

'Dead zone' area shrinking

Sep 30, 2004

A team of Texas A&M University and Louisiana State University scientists conducted a research cruise in late August to the "dead zone" - a region in the northern Gulf of Mexico that suffers from low oxygen and results in hu ...

Recommended for you

Dead floppy drive: Kenya recycles global e-waste

14 hours ago

In an industrial area outside Kenya's capital city, workers in hard hats and white masks take shiny new power drills to computer parts. This assembly line is not assembling, though. It is dismantling some ...

New paper calls for more carbon capture and storage research

19 hours ago

Federal efforts to reduce greenhouse gas emissions must involve increased investment in research and development of carbon capture and storage technologies, according to a new paper published by the University of Wyoming's ...

Coal gas boom in China holds climate change risks

Aug 22, 2014

Deep in the hilly grasslands of remote Inner Mongolia, twin smoke stacks rise more than 200 feet into the sky, their steam and sulfur billowing over herds of sheep and cattle. Both day and night, the rumble ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

superhuman
4 / 5 (6) Jul 25, 2009
The Gulf of Mexico's "dead zone" - where there is too little oxygen in the water for anything to live...

There is never "too little oxygen for anything to live" as plenty of microorganisms don't need oxygen at all.
deatopmg
4.7 / 5 (3) Jul 26, 2009
The doomsters lose another one. The sky is NOT falling!