Fears of collapse as coral reefs feel the heat
Under threat... coral can become bleached when water temperatures are too high.
by Marian Wilkinson, Environment Editor
May 13, 2009
http://www.smh.com.au/environment/global-warming/fears-of-collapse-as-coral-reefs-feel-the-heat-20090512-b1u3.html
THE most spectacular stretch of coral reefs on the planet is in danger of collapse from climate change, overfishing and pollution, according to a report being presented today at the World Oceans Conference in Indonesia.
Scientists consider the region known as the "coral triangle" to be the centre of marine life on Earth, teeming with fish and almost one-third of the world's coral reefs. Covering 1 per cent of the planet from South-East Asia to the Pacific, the area also supports about 100 million people.
But in the past 40 years, 40 per cent of the coral reefs and coastal mangroves in the coral triangle have been lost because of pollution, coastal development and overfishing, said a University of Queensland professor, Ove Hoegh-Guldberg, who led the study commissioned by WWF.
"It's an astounding amount," Professor Hoegh-Guldberg said. "At the moment the coral reefs are disappearing at about 1 to 2 per cent a year. You don't have to be a brain surgeon to see that within 40 years we could lose the rest. This may sound alarming but this is not alarmist. This is what we are probably going to experience if we don't get our act together".
To read the full article: http://www.smh.com.au/environment/global-warming/fears-of-collapse-as-coral-reefs-feel-the-heat-20090512-b1u3.html
Showing posts with label issue: coral reefs dying. Show all posts
Showing posts with label issue: coral reefs dying. Show all posts
Thursday, May 14, 2009
Friday, November 28, 2008
Marine Life Faces "Acid Threat"
Marine life faces 'acid threat'
By Julian Siddle
Science Reporter, BBC News
http://news.bbc.co.uk/2/hi/science/nature/7745714.stm
Man-made pollution is raising ocean acidity at least 10 times faster than previously thought, a study says.
Researchers say carbon dioxide levels are having a marked effect on the health of shellfish such as mussels.
They sampled coastal waters off the north-west Pacific coast of the US every half-hour for eight years.
The results, published in the journal PNAS, suggest that earlier climate change models may have underestimated the rate of ocean acidification.
Ocean pH
Professor Timothy Wootton from the department of ecology and evolution, University of Chicago, in Illinois, says such dramatic results were unexpected as it was thought that the huge ocean systems had the ability to absorb large quantities of CO2.
"It's been thought pH in the open oceans is well buffered, so it's surprising to see these fluctuations," he said.
The findings showed that CO2 had lowered the water pH over time, demonstrating a year-on-year increase in acidity.
The research involved taking daily measurements of water pH levels, salinity and temperature, off the coast of Tatoosh island, a small outcrop lying in the Pacific Ocean, just off the north-western tip of Washington state, US.
As well as measuring physical factors, the health of marine life present in the coastal ecosystem was also tracked.
Professor Wootton says biological factors were missing from previous models of ocean climate systems - and that life in the ocean, or in this case on the ocean edge, can also affect seawater pH.
"Over a short time, biology is affecting pH, through photosynthesis and respiration, but current models don't include biological activity as part of the story," he explained.
Calcium carbonate
Every summer, Professor Wootton returned to the same sites on Tatoosh island's windswept coasts, to look at the abundance and distribution of life at the water's edge. He was especially interested in barnacles, algae and the dominant species, the Californian mussel.
The mussel has a calcium carbonate -based shell, which can be weakened or even dissolved by exposure to acid. Professor Wootton says the increase in acidity may be responsible for the decline in mussels noted in the study.
"Patterns show the chances of mussels being replaced are higher than for species without calcified shells," he said.
Other species quickly move into the space previously occupied by the mussels - though one of these species, the barnacle, also has calcified shells.
To explain this apparent anomaly, Professor Wootton says the decline of the dominant species allows a window where another species may thrive - though he expects this to be temporary as the interloper too will eventually be affected by the increasing acidity.
"In the short term, the long term decline is offset by the release from competition," he explained.
It's going down 10 to 20 times faster than the previous models predicted
Professor Timothy Wootton, University of Chicago
Chemical oceanography
The researchers say they were surprised that the plants and animals in their study are so sensitive to CO2 changes. These organisms live in the harsh inter-tidal zones, they may be submerged under water, exposed to the sun, then lashed by waves and storms.
Professor Wootton says the most troubling finding is the speed of acidification, with the pH level dropping at a much greater rate than was previously thought.
"It's going down 10 to 20 times faster than the previous models predicted," he says.
The research team are now working together with chemical oceanographers to see how their coastal observations can be matched with large scale observations, to try to explain why the decline in pH levels seems to be happening so quickly.
"We actually know surprisingly little about how ocean acidity is changing over time, we need a broader network of measurements," said Professor Wootton.
By Julian Siddle
Science Reporter, BBC News
http://news.bbc.co.uk/2/hi/science/nature/7745714.stm
Man-made pollution is raising ocean acidity at least 10 times faster than previously thought, a study says.
Researchers say carbon dioxide levels are having a marked effect on the health of shellfish such as mussels.
They sampled coastal waters off the north-west Pacific coast of the US every half-hour for eight years.
The results, published in the journal PNAS, suggest that earlier climate change models may have underestimated the rate of ocean acidification.
Ocean pH
Professor Timothy Wootton from the department of ecology and evolution, University of Chicago, in Illinois, says such dramatic results were unexpected as it was thought that the huge ocean systems had the ability to absorb large quantities of CO2.
"It's been thought pH in the open oceans is well buffered, so it's surprising to see these fluctuations," he said.
The findings showed that CO2 had lowered the water pH over time, demonstrating a year-on-year increase in acidity.
The research involved taking daily measurements of water pH levels, salinity and temperature, off the coast of Tatoosh island, a small outcrop lying in the Pacific Ocean, just off the north-western tip of Washington state, US.
As well as measuring physical factors, the health of marine life present in the coastal ecosystem was also tracked.
Professor Wootton says biological factors were missing from previous models of ocean climate systems - and that life in the ocean, or in this case on the ocean edge, can also affect seawater pH.
"Over a short time, biology is affecting pH, through photosynthesis and respiration, but current models don't include biological activity as part of the story," he explained.
Calcium carbonate
Every summer, Professor Wootton returned to the same sites on Tatoosh island's windswept coasts, to look at the abundance and distribution of life at the water's edge. He was especially interested in barnacles, algae and the dominant species, the Californian mussel.
The mussel has a calcium carbonate -based shell, which can be weakened or even dissolved by exposure to acid. Professor Wootton says the increase in acidity may be responsible for the decline in mussels noted in the study.
"Patterns show the chances of mussels being replaced are higher than for species without calcified shells," he said.
Other species quickly move into the space previously occupied by the mussels - though one of these species, the barnacle, also has calcified shells.
To explain this apparent anomaly, Professor Wootton says the decline of the dominant species allows a window where another species may thrive - though he expects this to be temporary as the interloper too will eventually be affected by the increasing acidity.
"In the short term, the long term decline is offset by the release from competition," he explained.
It's going down 10 to 20 times faster than the previous models predicted
Professor Timothy Wootton, University of Chicago
Chemical oceanography
The researchers say they were surprised that the plants and animals in their study are so sensitive to CO2 changes. These organisms live in the harsh inter-tidal zones, they may be submerged under water, exposed to the sun, then lashed by waves and storms.
Professor Wootton says the most troubling finding is the speed of acidification, with the pH level dropping at a much greater rate than was previously thought.
"It's going down 10 to 20 times faster than the previous models predicted," he says.
The research team are now working together with chemical oceanographers to see how their coastal observations can be matched with large scale observations, to try to explain why the decline in pH levels seems to be happening so quickly.
"We actually know surprisingly little about how ocean acidity is changing over time, we need a broader network of measurements," said Professor Wootton.
Friday, October 31, 2008
CO2 Curbs May Be Too Late For Reefs
CO2 curbs may be too late for reefs, study warns
by David Adam, environment correspondent
The Guardian
Monday October 27 2008
http://www.guardian.co.uk/environment/2008/oct/27/coral-reefs-co2-wildlife-conservation/print
http://www.guardian.co.uk/environment/2008/oct/27/coral-reefs-co2-wildlife-conservation
A new global deal on climate change will come too late to save most of the world's coral reefs, according to a US study that suggests major ecological damage to the oceans is now inevitable.
Emissions of carbon dioxide are making seawater so acidic that reefs including the Great Barrier Reef off Australia could begin to break up within a few decades, research by the Carnegie Institution at Stanford University in California suggests. Even ambitious targets to stabilise greenhouse gas levels in the atmosphere, as championed by Britain and Europe to stave off dangerous climate change, still place more than 90% of coral reefs in jeopardy.
Oceanographers Long Cao and Ken Caldeira looked at how carbon dioxide dissolves in the sea as human emissions increase. About a third of carbon pollution is soaked up in this way, where it reacts with seawater to form carbonic acid. Experts say human activity over the last two centuries has produced enough acid to lower the average pH of global ocean surface waters by about 0.1 units.
Such acidification spells problems for coral reefs, which rely on calcium minerals called aragonite to build and maintain their exoskeletons.
"We can't say for sure that [the reefs] will disappear but ... the likelihood they will be able to persist is pretty small," said Caldeira.
The new study was prompted by questions by a US congressional committee on how possible carbon stabilisation targets would affect coral loss.
by David Adam, environment correspondent
The Guardian
Monday October 27 2008
http://www.guardian.co.uk/
http://www.guardian.co.uk/
A new global deal on climate change will come too late to save most of the world's coral reefs, according to a US study that suggests major ecological damage to the oceans is now inevitable.
Emissions of carbon dioxide are making seawater so acidic that reefs including the Great Barrier Reef off Australia could begin to break up within a few decades, research by the Carnegie Institution at Stanford University in California suggests. Even ambitious targets to stabilise greenhouse gas levels in the atmosphere, as championed by Britain and Europe to stave off dangerous climate change, still place more than 90% of coral reefs in jeopardy.
Oceanographers Long Cao and Ken Caldeira looked at how carbon dioxide dissolves in the sea as human emissions increase. About a third of carbon pollution is soaked up in this way, where it reacts with seawater to form carbonic acid. Experts say human activity over the last two centuries has produced enough acid to lower the average pH of global ocean surface waters by about 0.1 units.
Such acidification spells problems for coral reefs, which rely on calcium minerals called aragonite to build and maintain their exoskeletons.
"We can't say for sure that [the reefs] will disappear but ... the likelihood they will be able to persist is pretty small," said Caldeira.
The new study was prompted by questions by a US congressional committee on how possible carbon stabilisation targets would affect coral loss.
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