Monday October 5, 2009, 2:13 am
QUEENSLAND, Australia -- As human activity pumps more and more carbon into the atmosphere, a new threat has emerged to the world's coral reefs – starvation.

Scientists at the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland have discovered that the symbiotic algae – known as zooxanthellae – which supply 99 per cent of the corals' food supply may be disrupted by high CO2 levels and increased ocean acidification.
The result could be decreased productivity in corals, increasing their vulnerability to bleaching, diseases and other impacts, say PhD researcher Alicia Crawley, Dr Sophie Dove and colleagues, following investigations carried out at Orpheus Island Research Station on the Great Barrier Reef.

By exposing the algae to levels of CO2 likely to occur if the world fails to limit carbon emissions, the researchers found that production of a key enzyme that protects the symbiotic algae from sunlight is reduced by up to half.

“This enzyme provides protection to the zooxanthellae from harmful solar radiation while they are carrying out photosynthesis and producing energy for the corals,” Alicia explains.

“If the algae do not produce enough of this enzyme then the excess light causes oxidative stress, which in turn reduces their ability to convert sunlight into nourishment for the coral.”

“Should this effect continue for some time, the coral may actually expel the zooxanthellae, which is the cause of bleaching. If they do not then recover their algae quickly, the corals die of hunger.”

The researchers say the effect is independent of global warming, as it is driven primarily by increased emissions of CO2 to the atmosphere from the burning of fossil fuels, and the ocean acidification that results from them.

“Our research suggests that ocean acidification may present a double jeopardy for corals – on the one hand it will disrupt the process by which they form their chalky skeletons – the osteoporosis of the reef – and on the other, it will reduce their food supply from their zooxanthellae,” Dr Sophie Dove said.

The combined effect may exacerbate the impact of global warming on the world's reefs and the 500 million humans who depend on them, making coral ecosystems more vulnerable to bleaching at lower temperatures.

“This gives us yet another reason to reduce our CO2 emissions,” Ms Crawley said.

“Our research suggests there may be some benefits for zooxanthellae under lower carbon conditions – but not if we continue to pump out carbon dioxide at the rate we are now doing.”

“It is important to note that this enzyme represents just one change in coral organisms that will occur under high CO2. There are likely to be other changes that we haven't yet examined.

“However it is a further reason for Australia's leaders to act now to tackle climate change issues. The future of our coral reefs depends on it.”

Their article “The effect of ocean acidification on symbiont photorespiration and productivity in Acropora Formosa” appears in the online journal, Global Change Biology http://www3.interscience.wiley.com/journal/122314657/abstract

Monday October 5, 2009, 2:51 am
It would be terrible to see the loss of beautiful corals.Thanks Claudia!

Monday October 5, 2009, 2:58 am
thanks claudia if somrthing isn't done soon there will be nothing left to save

Monday October 5, 2009, 3:02 am
Again so sad these are so incredibly beautiful! ! We have to wake people up and get them to stop killing everything intentionally or not.
Thanks Claudia

Monday October 5, 2009, 3:25 am
There is too much CO2 because there is not enuff OXYGEN! (Also, H2O- Hydrogen and OXYGEN.)

They are cutting down too many OXYGEN producing trees! Nothing else will put oxygen back except trees. They need to knock it off with their logging and PLANT MORE TREES! SOON!

Monday October 5, 2009, 3:52 am
This is possibly in the medial future an unjustly fate for our coral and other plant life. The changes in our waters seem to have gone too far in the wrong direction. When you look back in the history reference noted before our time, when the ships that were in our waters were sail ships, no motors. You think how much better it was for our sea life no oils, no toxins, right there XXX’s out so many pollutants. The world of evolution isn’t always so good. Its ashame what we have gained and how much we are losing.
Sorry I got carried away.
Thanks Claudia

Monday October 5, 2009, 4:07 am
I once seen on TV the dying corals and that is a sad event.

Monday October 5, 2009, 6:49 am
I used to drive on coral reefs on the North Shore of Bermuda. Coral reefs bring to me a sight of astounding beauty. I cannot accept that this opportunity will be denied to my children and grandchildren because of human activity that creates more acid in the ocean's waters. This, Claudia, is tragic news to me. Necessary to know but it still causes me grief. Coral reefs have the greatest biodiversity on the planet. If, no probably when, we lose them, this destruction of habitat could contribute to the massive extinction event now going on planet-wide.

Monday October 5, 2009, 7:17 am
I wanted to send you five stars today, however c2 won't let me ! lololo Many thanks and stars for all you do ((((hugs))))

Monday October 5, 2009, 7:50 am
Thanxxx Sweetie... it is so sad that if the trend conitinues, we hav a high chance of loosing these wonderful edens under the sea... it would be a real loss and irreplaceable

Monday October 5, 2009, 8:01 am
When are we going to wake up? When the planet and its oceans are truly DEAD SEAS?

As we kill off everything aournd us we forget one thing: WE ARE NEXT IN LINE.

Thank you Claudia for a very informative article.

Monday October 5, 2009, 10:37 am
you know there are times when i feel lost ,duze man not know what damage he is causing or just not care,i realy donot get it.Thanx Claudia.

Monday October 5, 2009, 1:53 pm
The Great Barrier Reef only has around 20 years before it is dead! When will people stop playing and do something??????????

The destruction of the oceans will have a greater effect on us than the destruction of the rainforest.

Monday October 5, 2009, 2:03 pm
The Gulf of Mexico's dead zone has increased dramatically. What part of idiotic do these folks not get? Between the climate erosion and the plastic goop in our oceans, thanks to the idiots that throw that plastic bottle overboard, I don't understand why this is continuing and apparently, being allowed.

Monday October 5, 2009, 5:01 pm
Thanks Claudia, how sad to watch so much destruction of the environment caused by human activity. :(

Monday October 5, 2009, 7:32 pm
Beyond words. We can see the catastrophic consequences of human negligence increasing day after day and we go on destroying wildlife.