Ocean Dead Zones of the Pacific Northwest – January 6, 2009

“Dead Zones” were first reported and studied in 1910 — 4 areas in the world’s oceans. Currently the world-wide count is over 400. According to a study in the August 15 issue of the journal Science, the tally is 405 dead zones in coastal waters worldwide. These affect an area of 95,000 square miles, about the size of the country of New Zealand. Some of the increase is due to the discovery of low-oxygen areas that may have existed for years and are just being found, but others are actually newly developed.

Nancy N. Rabalais, executive director of the Louisiana University’s Marine Consortium, said she was not surprised at the increase in the number of identified dead zones. “There have been many more reported, but there truly are more that have not yet been identified.”

What has happened? The emergence of industrialized nations along with agriculture and business led to increased flux of nutrients from the land to the estuaries and the seas. It is now happening in developing countries. The number of dead zones has approximately doubled each decade since the 1960s.

What are dead zones? They are areas of sea floor with too little oxygen for most marine life. This condition is called “hypoxia.” Dead zones occur when excess nutrients, primarily nitrogen and phosphorus, enter coastal waters and help fertilize blooms of algae. When these microscopic plants die and sink to the bottom, they provide a rich food source for bacteria, which in the act of decomposition consume dissolved oxygen from surrounding waters. Major nutrient sources include fertilizers, farm runoff, sewage and the burning of fossil fuels.

“We have to realize that hypoxia is not a local problem,” said Robert J. Diaz of the Virginia Institute of Marine Science. Diaz began studying dead zones in the mid-1980′s. He continued, “It is a global problem and it has severe consequences for ecosystems. It’s getting to be a problem of such a magnitude that it is starting to affect the resources that we pull out of the sea to feed ourselves. If we screw up the energy flow within our systems we could end up with no crabs, no shrimp and no fish. That is where these dead zones are heading unless we stop their growth.”

“Farmers aren’t doing this on purpose,” Diaz said. “The farmers would certainly prefer to have their (fertilizer) on the land rather than floating down the river.”

Conventional cotton used in covers and cotton batting requires extremely high amounts of hazardous synthetic chemicals required for production. Seven of the top 15 pesticides used on cotton are classified as at least possible human carcinogens, and billions of pounds of nitrogen-based synthetic fertilizers are also used, resulting in runoff that can create aquatic Dead zones in waterways.
Manure is sometimes used as fertilizer because it contains large amounts of nitrogen and phosphorus, the very same nutrients which are attributed with the creation of the Dead zones, but over-saturated soils are not capable of absorbing the manure and, after a rain or irrigation, it runs off the land into rivers and streams. Municipal and domestic wastes include discharges from sewage treatment plants and storm water runoff from city streets, both of which have a high concentration of nitrogen and phosphorus. Atmospheric deposition results when nutrients settle in the waterways and the ocean directly from the air after being released by sources such as automobiles and fossil-fueled power plants.

Diaz says that many ecosystems experience a progression in which periodic hypoxic events become seasonal and then, if nutrient inputs continue to increase, persistent. Earth’s largest dead zone, in the Baltic Sea, experiences hypoxia year-round. Geologic evidence shows that dead zones were not “a naturally recurring event” in most other estuarine ecosystems. Dead zones were once rare. Now they’re commonplace. There are more of them in more places.

Diaz and collaborator Rutger Rosenberg of the University of Gothenburg in Sweden say that dead zones are now “the key stressor on marine ecosystems” and “rank with over-fishing, habitat loss, and harmful algal blooms as global environmental problems.” Diaz and Rosenberg write “There’s no other variable of such ecological importance to coastal marine ecosystems that has changed so drastically over such a short time as dissolved oxygen.”

The Pacific Northwest

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.

This year for the first time, the effect of the low-oxygen zone is also being seen in coastal waters off Washington, researchers at OSU and the Olympic Coast National Marine Sanctuary indicate.

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.”

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.

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

The “dead zone” now 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. KOMO 4 News reported that it could take hundreds of research trips off the state’s coast to determine whether fish kills are the result of an oxygen-depleted dead zone. New low-oxygen areas have been reported in Samish Bay off Puget Sound and Yaquina Bay in Oregon.

Dead zones off Oregon and Washington are likely tied to global warming, a study says. Low-oxygen areas that show scant signs of sea life have expanded. Peering into the murky depths, Jane Lubchenco, an Oregon State University marine ecologist, searched for sea life, but all she saw were signs of death. Video images scanned from the seafloor revealed a bone yard 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.

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 up welling 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 fishermen were the first to take note of Oregon’s dead zone. Al Pazar recalls his alarming 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 by crew men, be careful with those cute little things,” said Dennis Krulich, a longtime fisherman 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.

The Saanich Inlet on Vancouver Island, Canada, has a “sill” near the mouth of the inlet, about 70 meters deep, which restricts the exchange of water from the Pacific Ocean and the bottom of the inlet. For the same reasons given above, the bottom waters of the Saanich below 100 meters are also anoxic, and sediments from the Saanich have been studied to provide information about changing environmental conditions on the western coast of Canada. The Saanich sediments are particularly valuable because the have annual layers (varves). The study of the Saanich sediments can be compared to tree rings from trees over 12,000 years old that were found in a nearby lake.

The Puget Sound region’s best-known “Dead Zone” crops up frequently in the southern portion of Hood Canal. There, sunlight and high levels of nitrogen fuel blooms of algae that die, robbing the water of oxygen as they are eaten by bacteria, causing the fish to die out. The most recent big fish kill involved Dungeness crabs, shrimp and several species of finfish.

What are some solutions for cleaning up our marine waters and preventing pollution? Ask your state’s Governor to establish numeric nutrient standards to protect waters from pollution. You could make the following points:

Nutrient pollution is one of the biggest water quality problems in the nation.
The state has had many years to set numeric standards for nitrogen and phosphorus. Delay is only making pollution worse. The state should set these standards by no later than 2008.
The state standards should be set low enough to protect downstream waters from excessive nutrients. States are not allowed to contribute to the degradation of downstream waters.
It is important that the state set standards for all water bodies to ensure that nutrient pollution is reduced across the board. (Some states are planning to set standards for some water bodies, delaying standards for others.)
The state should follow the EPA’s technical guidance for developing standards. If not, the state must use a scientifically-defensible method. (Although states are free to use their own methods to develop standards, some states are developing their own methodologies more as a way to delay the process than to arrive at a standard which will protect water quality.)
The state should set standards for both nitrogen and phosphorus. (Some states are planning to address only one of these nutrients.)

Cleaning up and preventing future pollution will take new approaches and resources. The Washington State legislature can move to save Hood Canal and Puget Sound by focusing on the following:

Enhancing authority to control on-site septic systems (HB1458/SB5431) The legislature should provide clear authority for the state to regulate on-site septic pollution as well as provide new tools to help local authorities develop solutions. In areas of special concern, such as Hood Canal and Shellfish Protection Districts, local governments should develop enhanced programs approved by the state. Septic systems in these areas should be inspected and maintained on a regular basis.
Strengthening protections for watersheds and water quality around Puget Sound (HB1639/SB5619; HB1638/SB5618; HB1637/SB5620) The State needs to establish clear water quality objectives and provide adequate direction to local governments about strategies to control storm water and other sources of non-point pollution, particularly including measures to limit conversion of working forestlands. Additionally, landowners should receive tax incentives for voluntary conservation efforts along shorelines.
Making new investments in programs to prevent pollution. To comply with clean water standards, cities and counties need funds to pay for clean water projects, such as community septic systems, and funds to implement new safeguards, such as storm water programs. The pollution problem in Hood Canal indicates much of Puget Sound is in a critical state. Puget Sound is directly connected to the Pacific Ocean. We need to begin working now to reverse this decline in water quality, and guarantee that our marine waters are healthy for future generations. Our waterways deserve no less than the best protection possible.

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