Dead Zones off Oregon and Washington Likely Tied to Global Warming, Study Says

By kenneth R Weiss
The Los Angeles Times
15 February 2008

Low-oxygen areas that show scant signs of sea life have expanded. "We seem to have crossed a tipping point," a scientist says.

Newport, Oregon - Peering into the murky depths, Jane Lubchenco searched for sea life, but all she saw were signs of death.

Video images scanned from the seafloor revealed a boneyard of crab skeletons, dead fish and other marine life smothered under a white mat of bacteria. At times, the camera's unblinking eye revealed nothing at all - a barren undersea desert in waters renowned for their bounty of Dungeness crabs and fat rockfish.

"We couldn't believe our eyes," Lubchenco said, recalling her initial impression of the carnage brought about by oxygen-starved waters. "It was so overwhelming and depressing. It appeared that everything that couldn't swim or scuttle away had died."

Upon further study, Lubchenco and other marine ecologists at Oregon State University concluded that the undersea plague appears to be a symptom of global warming. In a study released today in the journal Science, the researchers note how these low-oxygen waters have expanded north into Washington and crept south as far as the California state line. And, they appear to be as regular as the tides, a lethal cycle that has repeated itself every summer and fall since 2002.

"We seem to have crossed a tipping point," Lubchenco said. "Low-oxygen zones off the Northwest coast appear to be the new normal."

Although scientists continue to amass data and tease out the details, all signs in the search for a cause point to stronger winds associated with a warming planet.

If this theory holds up, it means that global warming and the build-up of heat-trapping gases are bringing about oceanic changes beyond those previously documented: a rise in sea level, more acidic ocean water and the bleaching of coral reefs.

Low-oxygen dead zones, which have doubled in number every decade and exist around the world, have a variety of causes.

A massive dead zone off Louisiana is created each spring by a slurry of nutrient-rich farm runoff and sewage that flows out the Mississippi River, causing algae to bloom riotously, die and drift to the bottom to decompose. Bacteria then take over. In the process of breaking down the plant matter, they suck the oxygen out of the seawater, making it unable to support most forms of sea life.

Off Oregon, the dead zone appears to form because of changes in atmospheric conditions that create the oceanic river of nutrient-rich waters known as the California Current.

The California Current along the West Coast and the similar Humboldt Current off Peru and Benguela Current off South Africa are rarities. These powerful currents account for only about 1% of the world's oceans but produce 20% of the world's fisheries.

Their productivity comes from wind-driven upwelling of nutrient-rich waters from the deep. When those waters reach the surface and hit sunlight, tiny ocean plants known as phytoplankton bloom, creating food for small fish and shellfish that in turn feed larger marine animals up the food chain.

What's happening off Oregon, scientists believe, is that as land heats up, winds grow stronger and more persistent. Because the winds don't go slack as they used to do, the upwelling is prolonged, producing a surplus of phytoplankton that isn't consumed and ultimately dies, drifts down to the seafloor and rots.

"It fits a pattern that we're seeing in the Benguela Current," said Andrew Bakun, a professor at the University of Miami's Pew Institute for Ocean Science who wasn't part of the Oregon study. "It's reasonable to think these hypoxic and anoxic zones will increase as more greenhouse gases build up in the atmosphere."

The Benguela Current has seen sporadic dead zones. There, rotting clumps of algae have also released clouds of hydrogen sulfide gas that smell like rotten eggs and poison sea life. Residents along the coast of South Africa and Namibia have witnessed waves of rock lobsters crawl onto shore to escape the noxious gases.

Bakun considers the Benguela, the world's most powerful current, to be a harbinger of changes in other currents. His theory is that warm, rising air over the land makes upwelling more frequent and more intense. The phenomenon, he said, is complicated by decades of heavy fishing that has reduced schools of sardines to a tiny fraction of their former abundance.

Not enough fish remain to consume phytoplankton before it dies and settles on the bottom, creating an anoxic dead zone.

Crab fisherman were the first to take note of Oregon's dead zone. Al Pazar recalls his alarm in 2002 when he pulled up his traps and found something seriously amiss.

"It was a good amount of crabs," Pazar said. "But they were dead, or dying or very, very weak. Those that we managed to keep alive didn't survive for long."

The fishermen called Oregon State, which dispatched a boat of researchers to investigate.
"It was a big mystery," Lubchenco said. "We didn't know what was killing them."

Fishermen found other oddities. As they pulled up their crab traps, they found baby octopuses, about the size of silver dollars, inching their way up the lines toward the buoys floating on the surface.

"I'd tell my crewmen, be careful with these cute little things," said Dennis Krulich, a longtime fishermen in Newport. "Peel them off the rope, and we'll put them back."

Only later did he realize that these babies were coming up from oxygen-depleted waters that hover near the seafloor, climbing to save their lives. "In 30 years of crabbing, I'd never seen anything like it before, Krulich said.”It's spooky, this dead-zone thing."

The size of the zone has fluctuated over the years. In 2006, it was the largest ever measured, covering an expanse slightly larger than Rhode Island.

Last year, it was smaller but detected over a longer stretch of coastline.

To make sure the phenomenon was actually new, Oregon State marine ecologist Francis Chan reconstructed data from water sampling at 3,100 stations dating to 1950.

He found that low-oxygen areas have long existed in deeper waters, but there was virtually no evidence until recently of hypoxic waters in prime fishing waters, which extend down to 165 feet.

"It's pretty clear this is unprecedented," Chan said. "It's never been detected since we began to measure oxygen levels."

So far, the seasonal dead zones, which begin as early as June and wrap up in September, have not hurt the crab fishery, which mostly operates in the winter. Many crabs and fish manage to flee the low-oxygen area. And fishermen have learned to set their traps in the wasteland of the previous year's dead zones, to catch crabs that return to feed on the detritus of all the suffocated animals.

Scientists say seafood caught in low-oxygen zones is not harmful to eat.

Revealed: Polluting Impact of Humans on the Oceans

By Steve Connor
The Independent UK
15 February 2008

Almost every part of the world's oceans has been tainted to some extent by the destructive footprint of human activity, whether it is from overfishing and pollution or commercial shipping and coastal development.

For the first time, scientists have compiled a comprehensive map of the oceans showing the extent to which they have been damaged by man. The map integrates 17 different kinds of human activity - such as nitrogen fertilisers being washed into the sea from farming - and 20 types of ocean ecosystem, from coral reefs to mangrove forests, to study which parts of the marine environment have suffered most. The scientists found more than 40 per cent of the oceans bear the scars of serious environmental degradation and that only a small percentage have remained as pristine regions free of human influence.

The team of American scientists said the extent of the damage caused by man came as a shock although they believe the information they compiled could be used to improve the conservation and future protection of the marine environment.

The worst affected waters include large areas of the North Sea, the South and East China seas, the Caribbean Sea, the Atlantic off the east coast of North America, the Mediterranean, the Red Sea, the Bering Sea, parts of the western Pacific and the Persian Gulf.

Details of the study were presented yesterday to the American Association for the Advancement of Science in Boston by Ben Halpern of the University of California at Santa Barbara, who led the team of 19 experts from 16 different research centres.

"This project allows us to finally start to see the big picture of how humans are affecting the oceans. Our results show that, when these and other individual impacts are summed up, the big picture looks much worse than I imagine most people expected. It was certainly a surprise to me," Dr Halpern said.

"My hope is that our results serve as a wake-up call to better manage and protect our oceans rather than a reason to give up. Humans will always use the oceans for recreation, extraction of resources and for commercial activity such as shipping. That is a good thing. Our goal, and really our necessity, is to do this in a sustainable way so that our oceans remain in a healthy state and continue to provide use the resources we need and want."

The worst-affected marine ecosystems were coral reefs, nearly half of which have suffered badly, seagrass beds, mangrove forests in estuaries, underwater "mountain" ranges known as seamounts, rocky reefs and shallow continental shelves, especially those near densely populated areas, such as the North Sea.

"This study quantifies the extent of the problems marine scientists have long known to be issues," said John Bruno, a marine scientist at the University of North Carolina at Chapel Hill. "But it's not enough to just know something's a problem. If you want to do something about it you have to know where the problems are and what's causing them."

Ecological mapping in the past has tended to concentrate on one or two environmental factors covering areas with a resolution of 50 sq km. But the latest map integrates 17 aspects of global change, including warmer seas, to a resolution of 4 sq km.

Dr Bruno said: "This new database reveals for the first time the magnitude, geographic extent and precise locations of ocean warming. Armed with new information, the research team can begin to tackle the bigger problem of understanding and forecasting how ocean warming will affect marine ecosystems."

The scientists found that the most pristine oceans tended to be near the poles and there is concern about how they will be affected by future human activities brought about by the melting of polar sea ice, which enables ships to sail through larger areas of open water.

Data gathered for the global map could be used to bolster initiatives such as marine protected areas and ocean zoning which attempt to conserve the natural balance of ecosystems against human activity.

Dr Halpern said: "There is definitely room for hope. With targeted efforts to protect the chunks of the ocean that remain relatively pristine, we have a good chance of preserving these areas in good condition."

Elizabeth Selig of North Carolina University, a member of the research team, added: "This information enables us to tailor strategies and set priorities for the management of ecosystems. And it shows that while local efforts are important, we also need to be thinking about global solutions."