Coral reef species may adjust to climate change

Nicky Phillips Brisbane Times 22 Jul 11;

MANY of the world's coral reefs, including the Great Barrier Reef, could survive the coming decades if greenhouse gas emissions are reduced, a study has found.

While past research had predicted large-scale destruction from global warming was inevitable, recent studies have shown some species were more capable of adapting than others.

But the capacity for these corals to adjust could be greatly reduced by human activities such as over-fishing, pollution and habitat destruction.

As part of the study, published in the journal Science, scientists reviewed the most recent research on the effect of climate change on coral reefs, as well as evidence from the fossil record.

A marine biologist and study leader, John Pandolfi, said the response to climate change varied dramatically between regions.

''We can't say everywhere is doomed in two decades because CO2 is this level and pH is that level; it's just not that black and white,'' said Professor Pandolfi, from the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

''Our expectation is that some regions are less likely to completely collapse in the next few decades than others.''

A marine biologist and co-author of the study, Sean Connolly, also from the centre, said there was good evidence to show that past global warming and ocean acidification had had devastating impacts on coral reefs.

There was also evidence that marine species coped differently to ocean warming and coral bleaching.

He warned that the findings did not mean coral reefs were out of danger.

"There is no doubt that unchecked global warming would have a devastating affect on the world’s reefs," he said.

"If we do nothing, by later this century then all bets are off," Professor Connolly said.

"There is a wide range of responses to climate change among different organisms; some are already suffering with the climate change that has happened already, while others aren’t doing so badly," he said.

There was also uncertainty around which species would be able to adapt to rising temperatures and ocean acidification in time, he said.

Ocean acidification occurs when excess carbon dioxide in the atmosphere is absorbed by the ocean. Too much carbon dioxide reduces the availability of calcium carbonate, the building block of coral skeletons.

The rate of adaptation for many species could be increased if human activities such as fishing and runoff were managed appropriately.

To increase the ability for a species to adapt to one stress, others needed to be reduced, Professor Connolly said.

"The organisms that have an unusually good ability to cope with high temperatures and ocean acidification have to be able to survive and reproduce offspring that also have those tolerances. But if there is also a lot stress from coastal development [and] runoff then they can die out," he said.

Authorities also needed to ensure populations of marine species did not decline dramatically.

"If you reduce a population size you reduce its ability to adapt rapidly to environmental change," he said.