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Oregon dead zone event over, but cause still unknown

Oregon dead zone event over, but cause still unknown

Oregon dead zone event over, but cause still unknown
October 30, 2006

The hypoxic dead zone off the coast of Oregon has finally dissipated but researchers still don’t know why it has formed each of the past five summers.

The dead done, characterized by low oxygen levels, formed in mid-June this year and killed thousands of crabs, sea stars and marine worms. It was the strongest event ever recorded in the area.

“The figures were just off the charts this year,” said Dr. Francis Chan, a marine ecologist with Oregon State University. “We’re very interested now in seeing how the ocean recovers. There is much we don’t know about how sensitive or resilient these ocean systems are, but an event of this magnitude gives us the chance to gain some real insights into how marine systems function and can recover. We expect some fish to return fairly quickly, but with other life forms, it’s hard to say. And we have deadlines, we need to get a lot of this information before another possible hypoxic event starts next year.”

Scientists currently have poor understanding of what causes the conditions and say the dead zone could well return next year.

“Given what’s happened, it would not be surprising if hypoxic conditions developed next year as well, but we can’t say that for sure,” said Dr. Jack Barth, a professor of oceanic and atmospheric sciences at Oregon State University. “And we don’t know what is causing the change in wind patterns that ultimately results in marine hypoxia. There’s a pressing need to better understand these ocean systems, and all this points to an ongoing need for a better coast-wide observing system.”

Low oxygen conditions result from excessive phytoplankton blooms which are produced when unusual winds from the north disrupt the normal coastal currents that bring cold, nutrient-rich waters from the depths to the surface. The researchers say this year’s winds could become more typical in the future as a result of climate change.

The researchers note that the Oregon hypoxia is different from the “dead zones” that are caused by nutrient pollution in the Gulf of Mexico and other parts of the world.

This article used information from an Oregon State University news release.

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