Ocean dead zone off Oregon dissipating

GRANTS PASS, Ore. – An ocean dead zone off Oregon that killed fish, crabs and sea worms in an area bigger than Rhode Island last summer lasted nearly three times longer than any of its predecessors before dissipating with autumn’s change in the weather, scientists said Monday.

This year’s dead zone off Oregon ran for 17 weeks, compared to the previous high of six weeks in 2004, and saw oxygen readings near zero that left the ocean bottom littered with dead crabs, sea stars and sea anemones. This is the fifth straight year the dead zone returned. It covered 70 miles of the central Oregon Coast and there are indications a dead zone also formed off southern Washington.

Southerly winds in recent weeks have flushed out the oxygen-depleted waters that were stuck along the Continental Shelf off the central Oregon Coast, and put an end to the condition known as ocean upwelling that triggered the dead zone, Jack Barth, professor of physical oceanography at Oregon State University, said from Corvallis.

“The fact that we’ve seen five in five years now, and this one in 2006 was the most devastating does not bode well for the future,” Jane Lubchenco, a professor of marine biology at OSU who served on the Pew Oceans Commission, said from Corvallis. “We’re seeing a system that is acting very sporadically. It’s changing in ways we haven’t seen before, or at least we haven’t documented before. We can trace all those changes to changes in the winds.”

A recent United Nations report listed 200 dead zones around the world, including one off the mouth of the Mississippi River in the Gulf of Mexico. Almost all of them are caused by fertilizer and pollution running down rivers to feed huge algae blooms, which die and decompose on the bottom, depleting the water of oxygen.

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research thx to MD

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