*[Enwl] Gulf Oil Spill Expected to Create Huge Undersea Dead Zone

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Вт Июн 1 02:17:48 MSD 2010


Oil spill creates huge undersea 'dead zones'
      Clouds of crude and chemical dispersants have formed in the Gulf
of Mexico and oceanologists fear these could have devastating effects
on the food chain

By Emily Dugan
Sunday, 30 May 2010

The world's most damaging oil spill - now in its 41st continuously
gushing day - is creating huge unseen "dead zones" in the Gulf of
Mexico, according to oceanologists and toxicologists. They say that
if their fears are correct, then the sea's entire food chain could
suffer years of devastation, with almost no marine life in the region
escaping its effects.

While the sight of tar balls and oil-covered birds on Louisiana's
shoreline has been the most visible sign of the spill's environmental
destruction, many scientists now believe it is underwater
contamination that will have the deadliest impact. At least two
submerged clouds of noxious oil and chemical dispersants have been
confirmed by research vessels, and scientists are seeing initial
signs of several more. The largest is some 22 miles long, six miles
wide and 3,300 feet deep - a volume that would take up half of Lake
Erie. Another spans an area of 20 square miles.

More than 8,300 species of plants and animals are at risk. Some, such
as the bluefin tuna, which come to the Gulf to spawn, could even face
extinction. Scientists predict it will be many months - even years -
before the true toll of the disaster will be known.

In previous spills, oil rose to the surface and was dealt with there,
but due to the use of dispersants, as well as the weight of this
particular crude oil and the pressure created by the depth of the
leak, much of the oil has stayed submerged in clouds of tiny
particles. At least 800,000 gallons of dispersants were sprayed at
escaping oil in a frantic attempt to keep it offshore, but it now
seems this preventative measure has created a worse disaster. The
chemicals helped to keep the oil submerged and are toxic to marine
life, resulting in unprecedented underwater damage to organisms in
the Gulf.

Once these harmful substances enter the food chain, almost nothing
will escape their effects. Forests of coral, sharks, dolphins, sea
turtles, game fish and thousands of shellfish could all face
destruction. What happens next to these underwater clouds - or plumes
- depends largely on the currents. If they do eventually rise to the
surface, they may end up on the shoreline months or years from now,
causing a second wave of destruction.

The leak itself is far from over. With up to 40 million gallons of
oil now in the sea, efforts to plug the hole (disgorging up to 19,000
barrels a day) have become frantic. Since Wednesday, BP has been
trying to block the source by blasting it with mud and concrete. On
Friday, things took a more desperate turn as BP added a
dubious-sounding "junk shot" of shredded rubber and golf balls. BP's
chief operating officer, Doug Suttles, said yesterday: "To date it
hasn't yet stopped the flow. What I don't know is whether it
ultimately will or not."

"It's the biggest environmental disaster of our time and it's not
even over yet," said the marine toxicologist Dr Susan Shaw, director
of the Marine Environmental Research Institute based in Maine. She
has been diving among the damage and is horrified by the
contamination caused by BP's continued use of dispersants. "They've
been used at such a high volume that it's unprecedented. The worst of
these - Corexit 9527 - is the one they've been using most. That
ruptures red blood cells and causes fish to bleed. With 800,000
gallons of this, we can only imagine the death that will be caused."

According to Dr Shaw, plankton and smaller shrimps coated in these
toxic chemicals will be eaten by larger fish, passing the deadly mix
up the food chain. "This is dismantling the food web, piece by
piece," she said. "We'll see dead bodies soon. Sharks, dolphins, sea
turtles, whales: the impact on predators will be seen in a short time
because the food web will be impacted from the bottom up."

The largest of the clouds, confirmed by a University of South Florida
research ship last week, has gone deeper than the spill itself,
defying BP's assurances that all oil would rise to the surface. It is
now headed north-east of the rig, towards the DeSoto Canyon. This
underwater trench could channel the noxious soup along the Florida
coast, impacting on fisheries and coating 100-year-old coral forests.
Tests on the toxicity of another chemical cloud, some 10 miles long
and heading south-west of the site, are also being done by scientists
from the University of Georgia.

Marine biologists say the timing of this underwater contamination
could not be more catastrophic. "This is when all the animals are
reproducing and hatching, so the damage at this depth will be much
worse," said Dr Larry McKinney, director of the Harte Research
Institute for Gulf of Mexico Studies in Texas. "We're not talking
about adults on the surface; it will impact on the young - and
potentially a generational life cycle."

This could wipe out more precarious species. "Bluefin tuna spawn just
south of the oil spill and they spawn only in the Gulf. If they were
to go through the area at a critical time, that's one instance where
a plume could destroy a whole species."

What happens next to these suspended clouds worries scientists.
Nobody knows how long it will take them to reach the surface and come
towards the shore (if they ever do).

Dr Peter Roopnarine, an invertebrate zoologist and geologist at the
California Academy of Sciences, is conducting tests on molluscs. He
fears a second wave of wetland damage from these sub-surface plumes.
"The organisms we're working with are in shallow sub-tidal waters and
in the salt marshes, so we won't get immediate results from a plume.
But we could end up seeing two disasters on shore, because the plume
will eventually work its way there."

With no confirmation that BP's attempts to stop the flow of oil have
succeeded, the damage is likely to get worse. If this "top kill"
method of plugging the hole with concrete and mud fails, then the
only option left is a relief well, which will take until August at
the earliest to become operational. In the meantime, the surrounding
ocean will become deadlier every day that passes. And even if the
plug works, it may well be too late. As Dr McKinney pointed out: "At
the depth that these plumes are at, the sea will be toxic for God
knows how long."

Additional reporting by Sarah Morrison



http://www.independent.co.uk/news/world/americas/oil-spill-creates-huge-undersea-dead-zones-1987039.html


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