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In 2007, the “dead zone” in the Gulf of Mexico isn’t as large as predicted, but it’s still the third-largest dead zone ever mapped in the Gulf.

It’s an area about as big as the state of New Jersey, off the coast of Texas and Louisiana. That’s according to Nancy Rabalais, who led a team of scientists aboard a research vessel that mapped the extent of this year’s dead zone.

Rabalais – who is executive director of Louisiana Universities Marine Consortium – said what makes this water “dead” is a lack of oxygen. She said the lack of oxygen in Gulf of Mexico waters affects animals on the sea floor.

Usually, the fish are better swimmers. They can move out of the area faster. We’ve seen brown shrimp come up to the surface of the water. We’ve seen eels that live in the sediments come up to the surface of the water. And this is a trip of about 65 feet for these organisms to go from the bottom of the sediments all the way to the top. Not all of them are intended to be swimming organisms. They’re obviously stressed.

Rabalais said the size of the Gulf dead zone depends mainly on how much nitrogen runoff is carried by the Mississippi River to the Gulf. Nitrogen feeds algae, which eventually decomposes and depletes bottom waters of oxygen.

Our thanks to NOAA , the National Oceanographic and Atmospheric Administration.

总结
research vessel 研究船
sea floor 海底，海床
brown shrimp 褐虾
swimming organism 游泳生物
nitrogen runoff 氮素径流
decompose分解
deplete耗尽