Oceans heading for mass extinctions, experts warn

Written by  on June 21, 2011
Great Barrier Reef Park / AFP – Getty Images file
http://www.msnbc.msn.com/id/43479398/ns/world_news-world_environment/#

Thissection of Australia’s Great Barrier Reef in
2009 saw “bleaching” of coralcaused by warmer
than normal ocean temperatures. Bleaching can kill
reefs if it is prolonged.

msnbc.com staff and news service reports

coral-bleaching
WASHINGTON— Mass extinctions of species
in the world’s oceans are inevitable if current
trends of overfishing, habitat loss, global
warming and pollution continue, a panel of
renowned marine scientists warned Tuesday.

The combination of problems suggests there’s
a brewing worldwide die-off of species that
would rival past mass extinctions, the 27
scientists said in a preliminary report
presented to the UnitedNations

.

Vanishing species — from sea turtles to coral

— would upend the ocean’s ecosystem. Fish
are the main source of protein for a fifth of the
world’s population and the seas cycle oxygen
and help absorb carbon dioxide, the main
greenhouse gas from human activities.

“Things seem to be going wrong on several
different levels,” said Carl Lundin, director of
global marine programs at the International
Union for Conservation of Nature, which
helped produce the report with the
International Programme on the State of the
Ocean.

Some of the changes affecting the world’s seas
— which have been warned about individually
in the past — are happening faster than the
worst case scenarios that were predicted just
a few years ago, the report said.

“It was a more dire report than any of us
thought because we look at our own little
issues,” Lundin said. “When you put them all
together, it’s a pretty bleak situation.”

Climate and coral
Coral deaths alone would be considered a
mass extinction, according to study chief
author Alex Rogers of the University of
Oxford. A single bleaching event in 1998 killed
one-sixth of the world’s tropical coralreefs

.
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Oceans heading for mass extinctions, experts warn
Scientist: Situation is ‘more dire’ than any of us thought
Lundin pointed to deaths of 1,000-year-old
coral in the Indian Ocean and called it “really
unprecedented.”

“Not only are we already experiencing severe
declines in many species to the point of
commercial extinction in some cases, and an
unparalleled rate of regional extinctions of
habitat types (e.g. mangroves and seagrass
meadows), but we now face losing marine
species and entire marine ecosystems, such as
coral reefs, within a single generation,” the
experts said.

The chief causes for extinctions at the moment
are overfishing and habitat loss, but global
warming

is “increasingly adding to this,” the report
said.

Carbon dioxide from the burning of fossil
fuels ends up sinking in the oceans, which
then become more acidic, devastating
sensitive coral reefs. Warmer ocean
temperatures also are shifting species from
their normal habitats, Rogers said. Non-native
species moving into new areas can cause
havoc to those ecosystems.

Jelle Bijma, of the Alfred Wegener Institute,
said the seas faced a “deadly trio” of threats of
higher temperatures, acidification and lack of
oxygen that had featured in several past mass
extinctions.

Runoff from fertilizers into rivers and seas has
reduced oxygen in those areas, creating
dozens of “dead zones” around the globe.
The U.S. Geological Survey earlier this month
said it expects the dead zone from the
Mississippi River to set a record when it builds l
ater this summer due to flooding runoff.

“From a geological point of view, mass
extinctions happen overnight, but on human
timescales we may not realize that we are in
the middle of such an event,” Bijma wrote.

Chemicals and plastics from daily life also are
causing problems for sea creatures, the report
said. Overall, the world’s oceans just cannot
bounce back from problems — such as oil
spills — like they used to because of all the
compounding factors, scientists said.

Confounding the most dire predictions, the
GulfofMexico

has bounced back from last year’s major oil
spill, but it is still dealing with the growing
“dead zone” and above average sea
temperatures.

Similar ‘stressors’ in past extinctions
Describing the multiple events affecting the
world’s oceans as high intensity “stressors,”
the experts said similar compounding led to
the previous five mass extinction events in the
past 600 million years — most recently when
the dinosaurs vanished 65 million years ago,
apparently after an asteroid struck.

Data: The rise and fall of Earth’s
species (on this page)

The conclusions follow an international
meeting this spring in England to discuss the
fate of the world’s oceans. A full report will be
published later this year, the panel said.

Lundin said that “some of these things are
reversible if we change our behavior.”

Overfishing is the easiest for governments to
address, the experts said.

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“Unlike climate change, it can be directly,
immediately and effectively tackled by policy
change,” said William Cheung of the University
of East Anglia. “Overfishing is now estimated
to account for over 60 percent of the known
local and global extinction of marine fishes.”

Among examples of overfishing are the
Chinese bahaba. Its swim bladder is desired in
Asia as a medicinal product, and the cost per
kilo (2.2 pounds) has risen from a few dollars
in the 1930s to $20,000-$70,000 today.

Listed as critically endangered, the bahaba is
just one of more than 500 marine species
threatened by overfishing, Cheung noted. “The
only chance for many of these species to
recover is to stop overfishing and protect
them so that the populations can rebuild,” he
added.

“If action is not taken immediately, our
generation will see many more species follow
the footsteps of the Chinese bahaba,” Cheung
said.

Steve Murawski, a University of South Florida
professor and previously chief science advisor f
or the U.S. National Marine Fisheries Service,
said “it’s difficult to judge the veracity of the
results or the scientific support” for the
findings because the full report hasn’t been
published.

But he noted that in the United States “a strong
set of management requirements backed by
the force of law have resulted in an end to
domestic overfishing.”

“This is of course a very hopeful sign because
the USA is such an important fishing nation,”
he added. “Is the record commensurate
globally? No it is not, and thus I would
certainly support” the panel’s advice to reduce

global fishing “to levels commensurate with
long-term sustainability of fisheries and the
marine environment.”

The Associated Press and Reuters contributed to this
report.

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