wild places | wild happenings | wild news
make a difference for our wild places

home | links | search the site
  all articles latest | past | articles by topics | search wildnews
wild news on wildsingapore
  Yahoo News 11 Aug 06
Pacific 'dead zone' said to exceed fears
By Joseph B. Frazier, Associated Press Writer

Yahoo News 7 Aug 06
Scientists: Warming triggers 'dead zone'
By Jeff Barnard, Associated Press Writer

GRANTS PASS, Ore. - Bottom fish and crabs washing up dead on Oregon beaches are being killed by a recurring "dead zone" of low-oxygen water that is larger than in previous years and may be triggered by global warming, scientists said.

There are signs it is spreading north to Washington's Olympic Peninsula. Scientists studying the 70-mile-long zone of oxygen-depleted water, along the Continental Shelf between Florence and Lincoln City, conclude that it is being caused by explosive blooms of tiny plants known as phytoplankton, which die and sink to the bottom, then are eaten by bacteria which use up the oxygen in the water. The recurring phytoplankton blooms are triggered by northerly wind, which generates a process known as upwelling in which nutrient-rich water is brought to the surface from lower depths.

"We are seeing wild swings from year to year in the timing and duration of the winds that are favorable for upwelling," Jane Lubchenco, professor of marine ecology at Oregon State and a member of the Pew Oceans Commission, said from Corvallis. "This increased variability in the winds is consistent with what we would expect under climate change."

Scientists first noticed a dead zone off Newport in 2002. That one was traced back to a rare influx of cold water rich in nutrients and low in oxygen that had migrated from the Arctic, said Jack Barth, professor of oceanography at Oregon State and with Lubchenco a principal investigator for the Partnership for Interdisciplinary Studies of Coastal Oceans.

Dead zones have returned each summer since then, but these have been marked by intense bursts of upwelling that were followed by calm periods, when the water contains lower nutrient levels, Barth added.

This year, the upwelling started strongly in April, stalled in May and picked up again in late June. Following the upwellings, scientists found the oxygen levels lower.

"We know it's not pollution. It's not a toxic algal bloom. The simple fact is there's not enough oxygen," said Francis Chan, a research professor of zoology at Oregon State who has been measuring ocean oxygen levels.

Oxygen levels are generally lower in deeper water, said Lubchenco, but what is unusual about this condition is that it is moving into relatively shallow water, about 50 feet deep, and moving toward shore, where the richest marine ecosystems are.

Deep water fish, such as ling cod, wolf eels and rockfish, are showing up in Oregon tide pools, apparently driven toward shore by the advancing dead zone, said Lubchenco. Although the dead zone has been documented along 70 miles of coast, dead crabs and fish also have been showing up along Washington's Olympic Peninsula, Barth said.

"If we continue like we are now, we could see some ecological shifts," Barth said. "It all depends on what happens with the warming and the greenhouse gases."

Dead zones in other places around the country, such as Hood Canal in Washington and the Mississippi River Delta off Louisiana are caused by agricultural runoff fueling blooms of algae that rot and deplete oxygen levels, said Lubchenco. But dead zones like the one off Oregon also occur off Namibia and South Africa in the Atlantic and off Peru in the Pacific.

"We're not really sure what is down the road. If it's just for a short period of time, it will not be as devastating as if it starts lasting a significant fraction of summer," she said.

Yahoo News 11 Aug 06
Pacific 'dead zone' said to exceed fears
By Joseph B. Frazier, Associated Press Writer

PORTLAND, Ore. - Scientists say the oxygen-starved "dead zone" along the Pacific Coast that is causing massive crab and fish die-offs is worse than initially thought.

Scientists say weather, not pollution, appears to be the culprit, and no relief is in sight. However, some say there is no immediate sign yet of long-term damage to the crab fishery.

Oregon State University scientists looking for weather changes that could reverse the situation aren't finding them, and they say levels of dissolved oxygen critical to marine life are the lowest since the first dead zone was identified in 2002. It has returned every year.

Strong upwelling winds pushed a low-oxygen pool of deep water toward shore, suffocating marine life, said Jane Lubchenco, a professor of marine biology at OSU. She said wind changes could help push that water farther out but current forecasts predict the opposite.

After a recent trip to the dead zone and an inspection via camera on a remote-controlled submarine, she said, "We saw a crab graveyard and no fish the entire day." "Thousands and thousands of dead crab and molts were littering the ocean floor. Many sea stars were dead, and the fish have either left the area or have died and been washed away," she said. "Seeing so much carnage on the video screens was shocking and depressing."

The effect on the commercial fishery isn't yet known, said Hal Weeks, a marine ecologist with the Oregon Department of Fish and Wildlife. "The last two years have been record-breaking years in Oregon for Dungeness crab" despite dead zones, he said. "In that fishery there has been no apparent effect. That doesn't mean there won't be," he said.

It is Oregon's most valuable fishery, worth as much as $44 million in recent years.

But Weeks said crab populations fluctuate wildly for reasons not well understood. Whether any harvest decline is a result of normal fluctuation or the effects of the dead zone is hard to say, he said.

He said some reports indicate the loss of fin fish may be due to their movement to areas with more oxygen rather than to mortality.

Al Pazar, chairman of the Oregon Dungeness Crab Commission and a crab fisherman out of Newport, said this season is shaping up to be the second-best ever, around 28 million pounds, but that most crabs are caught in the six or eight weeks following the season's winter opening, well ahead of the appearance of the dead zones.

Few boats are fishing now, he said, and the season closes at midnight Monday.

But he said the affected area is a major crab producer, "right in the thick of it." He said he saw OSU videos from the zone "that made my knees weak."

The 2002 dead zone was the worst until this year's, he said. After 2002, he returned to the area when the season reopened and had good results. "They do move back in," he said.

Oregon State scientists working with the Oregon Department of Fish and Wildlife used a remote-control device Aug. 8 to check biological impact and continue oxygen sampling.

Dissolved oxygen readings off of Cape Perpetua north of Florence are between 3 percent and 10 percent of levels needed for survival and near zero in some areas.

"Some of the worst conditions are now approaching what we call anoxia, or the absence of oxygen," said Francis Chan, a marine ecologist with Oregon State and the OSU-based Partnership for Interdisciplinary Studies of Coastal Oceans. "This can lead to a whole different set of chemical reactions," he said. "It's hard to tell just how much mortality, year after year, these systems are going to be able to take."

A reef near Yachats normally swarms with rockfish, but they are gone. Dead Dungeness crab, sea stars and other marine life carpet the ocean floor. Scientists say water near the bottom is filled with "marine snow," fragments of dead marine life. As it decays, bacteria move in to feed on it and suck remaining oxygen from the water.

"We can't be sure what happened to all the fish, but it's clear they are gone," Lubchenco said. Similar but lesser zones have been found elsewhere along the Oregon and Washington coasts.

Scientists say they don't yet know how widespread it is.

There are no seafood safety issues, OSU experts say. Only live crabs and other fresh seafood are processed for sale.

Researchers say they don't know why it has become an annual event and can't yet tie it to climate change or global warming. The zone this year was spotted about a month ago. Some dead zones been caused by agricultural runoff. Those similar to Oregon's have been found off of Africa in the Atlantic and Peru in the Pacific.

Related articles on Wild shores
about the site | email ria
  News articles are reproduced for non-profit educational purposes.

website©ria tan 2003 www.wildsingapore.com