Dead Zone Reappears Off the Oregon Coast

CORNELIA DEAN / New York Times 6aug2006

For the fifth year in a row, unusual wind patterns off the coast of Oregon have produced a large “dead zone,” an area so low in oxygen that fish and crabs suffocate.

This dead zone is unlike those in the Gulf of Mexico and elsewhere, which result from fertilizer, sewage or runoff from hog or poultry operations carried by rivers. The Oregon zone appears when the wind generates strong currents carrying nutrient-rich but oxygen-poor water from the deep sea to the surface near shore, a process called upwelling.

The nutrients encourage the growth of plankton, which eventually dies and falls to the ocean floor. Bacteria there consume the plankton, using up oxygen.

Jane Lubchenco, a marine biologist at Oregon State University, said the phenomenon did not appear to be linked to recurring El Niño or La Niña currents or to long-term cycles of ocean movements. That made Dr. Lubchenco wonder if climate change might be a factor, she said, adding, “There is no other cause, as far as we can determine.”

The dead zone, which appears in late spring and lasts a matter of weeks, has quadrupled in size since it first appeared in 2002 and this year covers about 1,235 square miles, an area about as large as Rhode Island, Dr. Lubchenco said.

The zone dissipates when winds shift.

It is not clear what effect the dead zone may have on future fish or crab catches, Dr. Lubchenco said. So far, she said, the dead zone has not formed until the Dungeness crab season has been nearly over.

Hal Weeks, a marine ecologist who leads the Marine Habitat Project for the Oregon Department of Fish and Wildlife, said the formation of the low-oxygen, or hypoxic, areas had so far caused “localized disruptions” in fishing but no overall decline in catches and no interference with recreational fishing.

Dr. Weeks said these areas might have occurred in the past and gone undetected. But he added that when he convened a meeting of scientists and fishermen about 18 months ago to discuss the issue, the fishermen said they did not recall problems occurring so regularly.

“Based on people’s memories,” Dr. Weeks said, “they did not have a pattern or periodicity to it.”

He and Dr. Lubchenco said scientists would take a research vessel out to sea on Tuesday and lower a robot vehicle to photograph the sea bottom to check fish and crab mortality.

“You don’t normally haul up a pot and find any dead crabs in it,” Dr. Lubchenco said. “And the crabbers that we have talked to have all reported dead crabs.”

Dr. Weeks said he hoped the research cruise would help explain what was going on. “I am expected to give the best possible technical advice to my managers,” he said, “and I am afraid right now I don’t have answers for them.”

In 2002 when the dead zone first appeared, Dr. Lubchenco said, she and other researchers dismissed it as an interesting anomaly. “But now, five years in a row, we are beginning to think there has been some sort of fundamental change in ocean conditions off the West Coast,” she said, possibly because of changes in the jet stream caused by global warming.

source: http://www.nytimes.com/2006/08/06/us/06coast.html?_r=1&oref=slogin&pagewanted=print 6aug2006

Dead Zone Suspected in Fish Die-Off 

SANDI DOUGHTON / Seattle Times 27jul2006

A "dead zone" of oxygen-poor water has appeared off the Oregon coast for the fifth year in a row, and reports of crab and fish dying off Washington's Pacific shore suggest the phenomenon is occurring here, too.

Members of Washington's Quinault Indian Nation spotted large numbers of dead greenling, rockfish and flatfish on the beach last week. Some live fish were trapped in tide pools, including rat fish — a deep-water species.

"That tells us they were running from something," said Joe Schumacker, of the tribe's fisheries department. "If you're a fish looking for oxygen, the surf zone is where you would want to go."

Dead crab have been reported along the coast in Washington and Oregon by fishermen and observers on shore.

Preliminary data collected by researchers from the Olympic Coast National Marine Sanctuary show low oxygen levels along portions of the state's northern coastline, but it will be a couple of weeks before more complete numbers are in.

"We don't have a full picture yet," said Mary Sue Brancato, resource-protection coordinator for the sanctuary.

With a more extensive monitoring network, researchers at Oregon State University have no doubt a massive dead zone is parked a couple of miles off their state's coast. If northerly winds continue pushing the oxygen-depleted water toward shore, die-offs on par with those of 2002 are possible, OSU marine ecologist Francis Chan said.

That was the first year scientists detected the low-oxygen zone, alerted by widespread reports of suffocating fish and crab.

Since then, dead zones of varying scope and intensity have formed every summer, said OSU marine biologist Jane Lubchenco.

"We think that is signaling a fundamental change in atmospheric conditions," she said.

Shifting winds seem to be the main factor responsible for the dead zones' formation. Those winds are determined by land and sea temperatures — both of which have been rising as a result of global warming.

"We're seeing wild shifts from year to year in the winds that drive this system," Lubchenco said. "This increased variability is exactly what climate change models predict ... but we can't definitively say this is because of climate change."

Dead zones caused primarily by polluted runoff have formed in several marine areas around the world, including the Gulf of Texas and Washington's Hood Canal.

But pollution doesn't appear to play a role off the Pacific coast, Lubchenco said.

What does seem to be key is the wind-driven process of upwelling. Normally considered a good thing, upwelling brings deep, nutrient-rich waters to the shallow ocean, fueling the food web.

But deep waters are naturally low in oxygen, and if the process is knocked slightly askew, the result can be deadly for sea life.

Most of the dead zones off the Oregon coast seem to have been caused mainly by changes in wind patterns, which lead to intense spurts of upwelling, followed by calm periods.

During the calm, tiny plants proliferate madly, then die. Their decomposition robs the water of oxygen.

Washington scientists started taking continuous oxygen readings this year, Brancato said. Before that, spot measurements suggested oxygen depletion but weren't definitive.

"This is the first time we are going to be able to correlate oxygen levels with observational data from crab fishermen and shore-based volunteers," she said.

source: http://seattletimes.nwsource.com/cgi-bin/PrintStory.pl?document_id=2003155114&zsection_id=2002111777&slug=deadzone27m&date=20060727 6aug2006

OSU Researchers:
Recurring Dead Zone Off Oregon is Spreading

Salem News 6aug2006

CORVALLIS — A hypoxic “dead zone” has formed off the Oregon Coast for the fifth time in five years, according to researchers at Oregon State University.

A fundamental new trend in atmospheric and ocean circulation patterns in the Pacific Northwest appears to have begun, scientists say, and apparently is expanding its scope beyond Oregon waters.

There have been reports of dead crabs stretching from the central Oregon coast to the central Washington coast. Some dissolved oxygen levels at 180 feet have recently been measured as low as 0.55 milliliters per liter, and areas as shallow as 45 feet have been measured at 1 milliliter per liter.

These oxygen levels are several times lower than normal, and any dissolved oxygen level below 1.4 milliliters per liter is hypoxic, capable of suffocating a wide range of fish, crabs, and other marine life.

"There is a huge pool of low-oxygen water off the central Oregon coast with values as low as 0.46 milliliters per liter,” said Francis Chan, marine ecologist in the OSU Department of Zoology and with the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO), a marine research consortium at OSU and other universities along the West Coast.

“OSU researchers have documented this year’s region of low-oxygen bottom waters from Florence to Cascade Head,” Chan said. “The lack of consistent upwelling winds allowed a low-oxygen pool of deep water to build up. Now that the upwelling-favorable winds are blowing consistently, we’re seeing that pool of water come close to shore and begin to suffocate marine life. If these winds continue to blow, we expect to see continued and possibly significant die-offs.”

As events such as this become more regular, researchers say, they appear less like an anomaly and more like a fundamental shift in marine conditions and ocean behavior. In particular, a change in intensity and timing of coastal winds seems to play a significant role in these events.

"We're seeing wild swings from year to year in the timing and duration of winds favorable for upwelling,” said Jack Barth, an oceanographer with PISCO and the OSU College of Oceanic and Atmospheric Sciences. “This change from normal seasonal patterns and the increased variability are both consistent with climate change scenarios."

Barth and his colleagues are working on new circulation models that may allow scientists to predict when hypoxia and these “dead zones” will occur. No connection has been observed between these events and other major ocean cycles, such as El Niño or the Pacific Decadal Oscillation.

The lack of wide-scale ocean monitoring makes determining the size and movement of the dead zone difficult, although some new instrumentation being used this year by OSU scientists is helping. Dissolved oxygen sensors have been deployed on the sea floor both close to shore and in 260 feet of water off Newport, some of which are sending data in near real-time.

In addition, a new underwater unmanned vehicle equipped with sensors to measure temperature, salinity, chlorophyll and dissolved oxygen is routinely sampling across central Oregon waters.

During normal years, cold water rich in nutrients but low in oxygen upwells from the deep ocean off Oregon, mixes with oxygen-rich water near the surface, causes some phytoplankton growth and provides the basis for a thriving fishery and healthy marine food chain. During dead zone periods, some of the normal processes – including wind and current conditions – can change. This allows huge masses of plant growth to die, decay and in the process consume even more of the available oxygen near the sea floor, causing hypoxic conditions for marine life.

The first event in 2002 caused a massive die-off of fish and invertebrate marine species on the central Oregon coast. Less severe and somewhat different events occurred in 2003, 2004 and 2005.

The 2006 “dead zone” has a wider north-south extent. Some crabbers in the central Washington coast reported all dead crabs in pots at depths of about 45-90 feet, north of the Moclips River. Large numbers of dead Dungeness crab have been reported on the beach as far north as Kalaloch. Numerous species of bottom fish have been found dead on the beach south of the Quinault River in Washington.

In Oregon, the most vulnerable area in recent years has been the central third of the coast between about Newport and Florence, where conditions seem to be conducive to the development of low-oxygen waters. It’s not always easy to measure the biological impact of the dead zones, because many dead animals may be washed out to the deep sea. But researchers say that this year’s event may ultimately be as severe as the first one in 2002, although it reflects slightly different wind and ocean current conditions.

Collaborating on this research are scientists from OSU, PISCO, the Oregon Department of Fish and Wildlife, National Oceanic and Atmospheric Administration, University of Washington and the Olympic Coast National Marine Sanctuary.

Researchers say that it’s difficult to tell what long-term ecological impacts these dead zone events may have on marine ecosystems.

“Many marine species live in fairly specialized ecological niches and any time you change the fundamental physics, chemistry and nature of the system, it’s a serious concern,” Barth said.

Jane Lubchenco, the Valley Professor of Marine Biology at OSU and principle investigator for PISCO, also said that the biological monitoring of species health and impacts in the nearshore Pacific Ocean is “grossly inadequate,” making it difficult to evaluate the long-term impacts of low-oxygen and other events

source: http://www.salem-news.com/articles/august012006/dead_zone_8106.php 6aug2006