'Dead Zones' off US west coast may be irreversible

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'Dead Zones' off US west coast may be irreversible

May 12, 2011 - 01:12
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Scientists work to explain why massive "dead zones" have been invading the US Pacific Northwest's near-shore waters since 2002. An oxygen-depleted "dead zone" the size of New Jersey is starving sea life off the coast of Oregon and Washington and will probably appear there each summer as a result of climate change, says Jack Barth, professor of physical oceanography at Oregon State University researcher.

Tide pool sea stars feast on Dungeness crabs that suffocated in the low oxygen waters of a dead zone.

Dead zones form where microscopic plants, known as phytoplankton, are fertilized by excess nutrients, such as fertilizers and sewage, that are generated by human activities and dumped into the ocean by rivers, or more rarely, where they are fertilized by naturally occurring nutrients. The result: blooms of organic matter that ultimately decompose through processes that rob the ocean of life-sustaining oxygen. Animals that fail to flee dead zones either suffocate or suffer severe stress.

Possible connections between climate change and the relatively recent formation of dead zones in the Pacific Northwest's coastal waters are currently being studied by a research team that is funded by the National Science Foundation and co-led by Jack Barth of Oregon State University (OSU) and Francis Chan of OSU.

The huge area off the coast of Oregon and Washington are one of 400 dead zones around the world, most of them caused by fertilizer and sewage dumped into the oceans in river runoff.

But the dead zone off the Northwest is one of the few in the world -- and possibly the only one in North America -- that could be impossible to reverse. That is because evolving wind conditions likely brought on by a changing climate, rather than pollution, are responsible, said Jack Barth

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