U.N.: Number of ocean 'dead zones' rise
By JOHN HEILPRIN, Associated Press Writer Thu Oct 19, 7:36 PM
ET
WASHINGTON - Scientists have found 200 "dead zones" in the world's
oceans places where pollution threatens fish, other marine life
and the people who depend on them. The
United Nations report Thursday showed a 34 percent jump in the
number of such zones from just two years ago.
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Pollution-fed algae, which deprives other living marine life of
oxygen, is the cause of most of the world's dead zones that cover
tens of thousands of square miles of waterways. Scientists chiefly
blame fertilizer and other farm run-off, sewage and fossil-fuel
burning.
Those contain an excess of nutrients, particularly phosphorous and
nitrogen, that cause explosive blooms of tiny plants known as
phytoplankton. When they die, they sink to the bottom, where they
are eaten by bacteria that use up the oxygen in the water.
"The low levels of oxygen in the water make it difficult for fish,
oysters and other marine creatures to survive as well as important
habitats such as sea grass beds," U.N. officials said. "These areas
are fast becoming major threats to fish stocks and thus to the
people who depend upon fisheries for food and livelihoods."
By 2030, the world's rivers will pump 14 percent more nitrogen into
seas and oceans than that found in the mid-1990s, according to new
U.N. research released at a meeting in Beijing.
Researchers led by Robert Diaz, a marine scientist at Virginia's
College of William and Mary, said they found new dead zones at the
Archipelago Sea in Finland; Fosu Lagoon in Ghana; Pearl River
estuary and Changjiang River in China; and Mersey River estuary in
Britain.
Other new zones found were at the Elefsis Bay and Aegean Sea in
Greece; Paracas Bay in Peru; Mondego River in Portugal; Montevideo
Bay in Uruguay; and in the western Indian Ocean.
The United Nations marine experts said the number and size of
oxygen-deprived zones has grown each decade since the 1970s.
Not all the dead zones persist year-round; some return seasonally,
depending on winds that bring nutrient-rich water to the
surface.
"It seems like a big jump in two years," said Nancy Rabalais,
executive director of the Louisiana Universities Marine Consortium,
who was not part of the U.N. research. She said an important factor
has been the huge increase in pollution from fast-developing
countries.
Rabalais, who has studied the Gulf of Mexico's massive dead zone
that is now the size of New Jersey, said marine creatures that swim
fast enough can usually escape.
"The things that are left behind are the ones that usually can't
survive," she said. When you consider the size of some of these
areas, it's removing what's considered the essential habitat for
fishes and crustaceans."
Other U.N. scientific findings released Thursday, however, raised
hopes for the recovery of damaged coral reefs, which serve as the
ocean's nurseries. It found that reefs bleached in the late 1990s
by high surface sea temperatures are affected by how polluted the
waters are.
"Coral reefs recovering faster are generally those living in marine
protected areas and coastal waters where the levels of pollution,
dredging and other kinds of human-induced disturbance are
considered low," the U.N. said.