Gulf of Mexico Dead Zone Shrinks

By Christie Nicholson
July 27, 2009 , Scientific American

[/Below is the original script. But a few changes may have been made during the recording of this audio podcast./]

*The Louisiana Universities Marine Consortium reports that the dead zone in the Gulf is much smaller this year than expected. Christie Nicholson reports*

At first glance it seems like good news: This summer the size of the Gulf of Mexico dead zone <> is less than half its forecasted size, measuring about 3,000 square miles, according to the Louisiana Universities Marine Consortium <>.

Well, it might be smaller—but unfortunately it’s more severe.

Typically dead zones affect waters near the ocean floor but this year the zone extends up closer to the surface.

Dead zones are waters that have become so choked of oxygen <> that they’re unable to support ocean life. Massive amounts of fertilizer runoffs from agricultural fields are what create such hypoxic waters <>. The fertilizer runoff nourishes algae which then feed microbes that consume oxygen.

Scientists say the current shrinkage of this year’s dead zone is due to short-term weather changes, not to any change in an underlying cause.

Unusual weather patterns this year brought high winds and waves in the Atchafalaya River delta and may have infused more oxygen in the shallow waters.

The Gulf of Mexico and Mississippi River Watershed Nutrient Task Force has a goal to reduce the dead zone <> (which on a five-year average measures 6,000 square miles) to 2,000 square miles by 2015.

And this is an important area because the Gulf of Mexico loses 212,000 metric tons of food due to hypoxia <>, and this threatens the fishing industry which generates about $2.8 billion annually.