Rapid Growth Found in Oxygen-Starved 'Dead Zones'

By BINA VENKATARAMAN
Published: August 14, 2008
Many coastal areas of the world’s oceans are being starved of oxygen at an alarming rate, with vast stretches along the seafloor depleted of it to the point that they can barely sustain marine life, researchers are reporting.
The main culprit, scientists say, is nitrogen-rich nutrients from crop fertilizers that spill into coastal waters by way of rivers and streams.
A study to be published Friday in the journal Science says the number of these marine “dead zones” around the world has doubled about every 10 years since the 1960s. About 400 coastal areas now have periodically or perpetually oxygen-starved bottom waters, many of them growing in size and intensity. Combined, the zones are larger than Oregon.
“What’s happened in the last 40, 50 years is that human activity has made the water quality conditions worse,” the study’s leader author, Robert J. Diaz, said in an interview.
The trend portends nothing good for many fisheries, said Dr. Diaz, a professor at the Virginia Institute of Marine Science at the College of William and Mary. “Dead zones,” he said, “tend to occur in areas that are historically prime fishing grounds.”
Indeed, while the size of dead zones is small relative to the total surface of the oceans, scientists say they account for a significant part of ocean waters that support commercial fish and shellfish species.