Gulf Coast Dead Zone Set to Grow

By David Biello reports (with narration by Christie Nicholson), SCIENTIFIC AMERICAN
July 4, 2010

There’s a dead zone forming in the Gulf of Mexico, and I’m not talking about the ongoing oil gushing from BP’s well.

No, it’s the annual dead zone that forms thanks to all the fertilizers washing off Midwestern farm fields.   These chemicals flow from tributaries into the Mighty Mississippi and then are carried by Old Muddy down to the Gulf.  

Once there the nitrogen promotes algae growth. When the algae dies, it sinks and microbes feast on its corpse, sucking oxygen out of the surrounding waters in the process.  

The result is deep water that’s devoid of oxygen. This is bad news for creatures on the sea floor such as coral or slow-moving crabs and worms.

Scientists at the Louisiana Universities Marine Consortium predict that this year’s dead zone will cover an area roughly the size of New Jersey, just shy of the record set back in 2002.  

Nearly 120,000 metric tons of nitrogen made it to the Gulf in May of this year. That makes for a big algae bloom and a big dead zone.  

What’s worse, the oil spill could make it even bigger. Turns out that the microbes cleaning up that mess use oxygen too.

—David Biello, with narration by Christie Nicholson