Ocean Dead Zones Expanding

U.S. and Swedish research suggests the number of dead zones in the world’s oceans has increased by a third since 1995.

Robert Diaz of the Virginia Institute of Marine Science at the College of William and Mary said dead zones — areas of the ocean with too little oxygen to support most marine life — “rank with overfishing, habitat loss and harmful algal blooms as global environmental problems.”

Agricultural fertilizers are one of the key causes of the dead zones, the Virginia Institute of Marine Science said in a release. “Scientists and farmers need to continue working together to develop farming methods that minimize the transfer of nutrients from land to sea,” Diaz said.

Rutger Rosenberg of the University of Gothenburg in Sweden collaborated on the research, which appears in the Aug. 15 issue of the journal Science.

The researchers counted 405 dead zones around the world, covering an area the size of New Zealand. The largest dead zone in the United States covers more than 8,500 square miles at the mouth of the Mississippi River.