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Ocean life 'facing mass extinction'
Depleted fish stocks, dying reefs and "dead zones" among consequences of global warming and pollution, scientists warn.
Last Modified: 21 Jun 2011 07:05
Overfishing and man-made problems are affecting oceans to a greater extent than previously thought [GALLO/GETTY]

Pollution, global warming and other man-made problems are pushing the world's oceans to the brink of a mass extinction of marine life unprecedented in tens of millions of years, a consortium of scientists has warned.

Dying coral reefs, biodiversity ravaged by invasive species, expanding open-water "dead zones," toxic algae blooms, and the massive depletion of big fish stocks are all accelerating, according to the report, which is due to be presented at the United Nations on Tuesday.

"We now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation,'' the report said.

Sponsored by the International Programme on the State of the Ocean (IPSO), the review of recent science found that ocean health has declined further, faster and to a far greater extent than dire forecasts only a few years ago.

These symptoms, moreover, could be the harbinger of wider environmental disruptions, scientists said.

All five mass extinctions of life on Earth - reaching back more than 500 million years - were preceded by many of the same conditions now afflicting the ocean environment.

The rate at which carbon is being absorbed by the ocean is already far greater than at the time of the last globally significant extinctions, which wiped out up to 50 per cent of some deep-sea animals, the report said.

Overfishing has also reduced some commercial fish stocks by more than 90 per cent, it said.

'Major extinction events'

Oceans under threat
Some of the factors increasing stress on the world's oceans:
  The rate at which the ocean absorbs carbon is far greater than the last time a global extinction of marine life occurred - an event which wiped out around 50% of deep sea animals.
  A single mass coral bleaching event in 1998 killed 16% of the world's tropical coral reefs.
  Overfishing has reduced some commercial fish stocks and populations of by-catch species by more than 90%.
 

Pollutants, including chemicals, are being traced in the Polar Seas, where they are often absorbed by tiny particles in the ocean, which are then digested by marine creatures.

"The results are shocking," said Alex Rogers, an Oxford professor who heads IPSO and co-authored the report. "We are looking at consequences for humankind that will impact in our lifetime."

Some of the changes affecting the world's seas are happening faster than the worst case scenarios that were predicted just a few years ago, the report said.

Mark Meekan, of the Australian Institue of Marine Science, told Al Jazeera that the "synergistic effect" of the changes to the planet's oceans was worrying.

"The outcome for us may be some major extinction events if things continue the way they are.

"The report says that we have less than a generation to act. But we really need to be concerned now. Because a lot of these problems, such as global warming, such as oceans certification, have what is called momentum," Meekan said.

"Very soon the feedback mechanisms that are in those processes may take the whole situation out of our hands ... The time to act is now. That's the time we can actually deal with the causes and not just the consequences."

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 coal and other fossil fuels ends up sinking in the ocean which then becomes more acidic. Warmer ocean temperatures are shifting species from their normal habitats, Rogers
said, while melting sea ice and glaciers are also having an impact.

Chemicals and plastics from daily life, and oil spills, also cause problems for sea creatures, the report said.

Source:
Al Jazeera and agencies
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