Dead zone rose up from ocean two years ago, scientists say
By Margarete Munro
Canwest News Service; February 14 and February 15, 2008
http://www.canada.com/theprovince/news/story.html?id=c5d0e85f-bac8-4aae-8c5a-6ae71981e99f&k=34729
Oxygen-deprived water rose up from the deep ocean two years ago, cutting a deadly swath along the Pacific Northwest coast, say scientists, who watched in awe as fish fled and crabs, sea stars and worms died en masse, creating a rotting carpet on the sea floor.
The "dead zone" was unprecedented say the researchers, who have been combing through the historic records to understand the phenomenon that bathed at least 3,000 square kilometres, from the Canadian border south to the central Oregon coast, in low-oxygen water in 2006.
The scientists report their findings in the journal Science today. They say it appears to be an increasingly common phenomenon as wind patterns shift along the Pacific coast.
Low-oxygen water has appeared in varying degrees since 2000, in bad years coming within just two kilometres of shore, says oceanographer Francis Chan of Oregon State University, lead author of the Science report that notes how sensitive the marine ecosystem off the Northwest Pacific is to "rapid reorganization."
Canadian researchers say they have been seeing changes in the winds and a drop in oxygen in waters off the B.C. coast as well. But so far "we’re escaping the killing, low-oxygen levels," says Bill Crawford, a research scientist with Fisheries and Oceans Canada.
He and his colleagues are hoping to secure federal funding to install a continuous oxygen monitoring station off southwest Vancouver Island, which Crawford says is probably the most vulnerable region in Canadian waters.
But he suspects oceanographic conditions, including the massive outflow of water from the Fraser River, protect Canada from the "killing waters" that have been smothering sea life across the border.
"It would be tricky for really low-oxygen water to cross and get into Canada," says Crawford, "but I’m not saying it couldn’t happen."
The problem starts in the spring and summer when winds from the north drive deep, low-oxygen water toward the surface "like a conveyor belt," says Chan.
The water is so nutrient-rich it acts like fertilizer, triggering a massive growth of plants and plankton, much of which dies, sinks to the bottom and decays, a process that further depletes the oxygen.
It has long been known that a giant pool of low-oxygen water sits offshore, about 600 to 800 metres below the surface.
Oxygen-deprived water rose up from the deep ocean two years ago, cutting a deadly swath along the Pacific Northwest coast, say scientists, who watched in awe as fish fled and crabs, sea stars and worms died en masse, creating a rotting carpet on the sea floor.
The "dead zone" was unprecedented say the researchers, who have been combing through the historic records to understand the phenomenon that bathed at least 3,000 square kilometres, from the Canadian border south to the central Oregon coast, in low-oxygen water in 2006.
The scientists report their findings in the journal Science today. They say it appears to be
Low-oxygen water has appeared in varying degrees since 2000, in bad years coming within just two kilometres of shore, says oceanographer Francis Chan of Oregon State University, lead author of the Science report that notes how sensitive the marine ecosystem off the Northwest Pacific is to "rapid reorganization."
Canadian researchers say they have been seeing changes in the winds and a drop in oxygen in waters off the B.C. coast as well. But so far "we’re escaping the killing, low-oxygen levels," says Bill Crawford, a research scientist with Fisheries and Oceans Canada.
He and his colleagues are hoping to secure federal funding to install a continuous oxygen monitoring station off southwest Vancouver Island, which Crawford says is probably the most vulnerable region in Canadian waters.
But he suspects oceanographic conditions, including the massive outflow of water from the Fraser River, protect Canada from the "killing waters" that have been smothering sea life across the border.
"It would be tricky for really low-oxygen water to cross and get into Canada," says Crawford, "but I’m not saying it couldn’t happen."
The problem starts in the spring and summer when winds from the north drive deep, low-oxygen water toward the surface "like a conveyor belt," says Chan.
The water is so nutrient-rich it acts like fertilizer, triggering a massive growth of plants and plankton, much of which dies, sinks to the bottom and decays, a process that further depletes the oxygen.
It has long been known that a giant pool of low-oxygen water sits offshore, about 600 to 800 metres below the surface.
