*Wild Wind shifts devastate ocean life*

By Jonathan Fildes
Science and technology reporter, BBC News, San Francisco

The delicate interplay between the oceans and atmosphere is changing
with catastrophic consequences.

Entire marine ecosystems have been wiped out, devastating populations of
sea birds and larger marine mammals.

These "dead zones" occur where there are disturbances to the
nutrient-rich ocean currents, which are driven by coastal winds.

Extreme marine suffocations have occurred off the west coast of the US
every year for the last five years.

The most intense event, which left the ocean floor littered with the
carcasses of crabs, happened in 2006.

Climate models predict increasing uncertainty with wild fluctuations. We
should expect more surprises
Dr Jane Lubchenco, OSU

It was unlike anything that we've measured along the Oregon coast in the
past five decades," said Dr Francis Chan, of Oregon State University (OSU).

Other coastal countries including Chile, Namibia and South Africa have
also been affected.

Plant bloom

The common factor between all of the areas is that marine currents off
the coast rise from the deep ocean.

These upwelling zones bring nutrient-rich water up from the deep,
triggering plankton blooms that underpin the coastal food chain. Nearly
50% of the world's fisheries are in these areas.

The currents are driven by winds that move surface water away from the
coast, drawing more up from the deep.

But now, observations along the west coast of the US suggest that the
upwelling is being disrupted, changing its timing and intensity.

For example, in 2005 the upwelling was delayed which meant that the
plankton blooms did not occur, leading to a collapse in fish populations.

This particularly hit migrating salmon, which pass along the coast in
April and May every year.

"In 2005 they found nothing to eat," said Dr Bill Peterson of the
National Oceanic and Atmospheric Administration (Noaa). "By the time
upwelling started, they were dead."

Huge graveyard

An even more catastrophic event occurred in 2006 when the amount of
upwelling doubled, leading to a huge influx of nutrients and a
supercharged plankton bloom.

When these sank to the ocean floor they stripped the water column of
oxygen, creating a 3,000 sq km (1,150 sq miles) dead zone, where
creatures unable to swim away suffocated en masse.

Dr Francis Chan used underwater cameras to survey the area two months
after the event.

"We were shocked to see a graveyard," he said. "Frame after frame of
carcass, carcass, carcass."

Crabs, worms and sea stars all perished in the anoxic water.

The event was so severe that the researchers fear that marine life
cannot return to the area.

"In previous years, fish that have escaped the low-oxygen area appear to
have returned once the oxygen was renewed," said Dr Jane Lubchenco, also
of OSU.

"This year may be different, however, because unlike earlier years, the
living habitat was also suffocated."

Uncertain future

The researchers believe the cause of these events was changes in the
intensity of the coastal winds, perhaps brought about by global warming.

"What we know from the climate change models is that the land will warm
more than the sea," colleague Jack Barth told the BBC News website.

It is this difference in temperature and pressure that drives the winds.

"As you intensify that gradient - that will drive the stronger winds."

To confirm this link to climate change, the researchers say they need
another 10 to 15 years of data.

In the meantime, they say, we must change our approach to managing and
using these ecosystems, particularly for fish stocks.

"The most prudent course of action is to begin to think differently
about what is happening," said Dr Lubchenco.

"Climate models predict increasing uncertainty with wild fluctuations.
We should expect more surprises."

The research was presented at the American Association for the
Advancement of Science (AAAS) annual meeting in San Francisco, US.