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Up-close view of dead zone shows "it's just a wasteland"
Seattle Times staff reporter
ABOARD THE ELAKHA, off the Oregon Coast — In years past, the reef a few miles from Oregon's Cape Perpetua was a small underwater gem. It was favored by the quillback, black and canary rockfish, which darted among boulders bedecked with sea stars and anemones.
On Tuesday, underwater video cameras remotely operated from this research vessel sent back a starkly different view — a reef barren of fish but littered with what researchers estimated as thousands of carcasses of decaying crabs.
Worms, normally dug into sea sand, drifted dead along the bottom.
"It's just a wasteland down there," said Francis Chan, an Oregon State University marine ecologist aboard the Elakha. "I didn't expect to see anything quite like this."
These crabs and worms died because they proved too slow to move away from an extraordinary swath of oxygen-depleted water.
Scientists call this a dead zone.
Although this reef appeared to be a worst-case scenario, oxygen-poor water now stretches along 70 miles off the Oregon Coast. Oxygen-poor water also has been detected off the coast of Washington's Olympic Peninsula.
Scientists first detected the phenomenon in Northwest waters in the summer of 2002, and it has appeared every year since then.
On Monday at the reef off Cape Perpetua, researchers took the lowest oxygen readings ever noted in some 40 years of recordkeeping on Oregon coastal waters. They came back Tuesday with a camera to see what was there.
During the entire survey of a roughly 1,400-foot stretch of the reef, there were no confirmed sightings of any fish — dead or alive — on the reef. While some may have died and their bodies washed away, researchers hope most of the fish swam to more oxygen-rich waters.
The dead zone is caused by coastal upwellings as patterns that normally sustain life in the rich coastal waters become more erratic and destroy some life. The normal patterns are a mix of northerly winds that allow upwellings of cold, nutrient-rich deep water to occur and southerly winds that move about the oxygen-poor water.
The Pacific Northwest dead zone results from strong northerly winds that allow the cold water to surface without any mixer winds from the south. This produces a series of upwellings that pile too much oxygen-poor water into the coastal zone.
Researchers at OSU said the erratic wind patterns of recent years are consistent with changes predicted in computer models that attempt to simulate the effects of global warming. But they caution that at this point it is unclear what — if any — link the dead zone has to climate change.
"We can say that what we are seeing is totally consistent with the changes predicted by the models," said Jane Lubchenco, OSU marine ecologist.
Low-oxygen water is common off Washington's northern coast in late summer, said University of Washington oceanographer Barbara Hickey.
Last year, during a research cruise in the Olympic Coast National Marine Sanctuary near Kalaloch, she measured levels below 1 milliliter per liter on 10 days. For three days in September, the oxygen levels were below 0.5 milliliters per liter in shallow waters.
A research ship is working off the coast right now, and it should have some current figures within the next few days.
Even with the low oxygen levels off Oregon in recent years, the state still has some record crab harvests.
This year's dead zone does appear to be more intense in some areas.
Monday's reading off Cape Perpetua was 0.1 milliliter per liter, 25 times lower than the low end of normal for dissolved oxygen readings.
It was so radical a measurement that Chan didn't believe what he found until he double-checked the measurement back at his laboratory later that evening.
What happens next is uncertain.
If southerly winds kick up, then the dead zone could unravel. If northerly winds prevail, it could intensify, and Chan isn't sure what to expect.
"With oxygen readings this low, we are in uncharted territory," he said.
Seattle Times staff reporters Sandi Doughton and Christine Clarridge contributed to this report.
Hal Bernton: 206-464-2581Footnote
The Elakha: The Elakha is a research vessel operated by Oregon State University and the Oregon Department of Fish and Wildlife and sponsored by the Partnership for Interdisciplinary Studies of Coastal Oceans.
Copyright © 2006 The Seattle Times Company