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Many coastal areas of the creation’s oceans are being starved of oxygen at some alarming charge, with vast stretches beside the seafloor depleted of it to the point where they can barely keep from falling shipping life, researchers are reporting.

The main culprit, scientists said, is nitrogen-rich nutrients from crop fertilizers that spill into coastal waters by fashion of rivers and streams.

A study to be published today in the journal Science says the number of these saltwater “dead zones” in a circle the world has doubled about every 10 years since the 1960s. About 400 coastal areas acquire periodically or perpetually oxygen-starved bottom waters, many of them augmenting in size and intensity. Combined, the zones, one of which is in a desperation off a Skagit County island, are larger than Oregon.

“What’s happened in the last 40, 50 years is that human activity has made the water-quality conditions worse,” said the study’s leader author, Robert Diaz.

The trend portends non-existence good for many fisheries, said Diaz, a professor at the Virginia Institute of Marine Science at the College of William and Mary. “Dead zones,” he reported, “tend to occur in areas that are historically prime fishing grounds.”

Low oxygen, or hypoxia, is a weighty measure of the downstream effect of chemical fertilizers used in agriculture. Air pollution is another factor.

Hypoxia has been seen for decades in such places as the Chesapeake Bay, Lake Erie, the Gulf of Mexico and Long Island Sound, mete Diaz’s survey has found new zones in Washington state’s Samish Bay, Oregon’s Yaquina Bay, prawn culture ponds in Taiwan, the San Martin River in northern Spain and some fjords in Norway, Diaz said.

A dead zone has been newly reported opposite the mouth of the Yangtze River in China, Diaz declared, but the area probably has been hypoxic since the 1950s. “We good didn’t be sure around it,” he said.

“We’re saying that hypoxia is since far and near, it seems,” Diaz said. “We can say that human activities really screwed up oxygen conditions in our coastal areas.”

Douglas Rader, principal great sea scientist for the Environmental Defense Fund, said the chaos in the planet’s azote cycle is not only creating dead zones but in like manner inciting the spread of toxic algae, such as the pfiesteria that has appeared in recent years in the Chesapeake.

“The next big challenge, after global warming, is going to be addressing the massive upset of the world’s nitrogen cycle,” Rader said.

While the size of dead zones is mean relative to the total surface of the oceans, scientists said they chronicle for a significant part of ocean waters that support commercial fish and shellfish fashion.