Penny Timms reported this story on Monday, September 7, 2015 18:19:00

MARK COLVIN: There are still fears that warming sea temperatures may damage the Great Barrier Reef, but there's better news when it comes to acidification.



Scientists using specialist technology in Australia believe they've established that increasing levels of acid in the ocean will not speed up coral bleaching.



Penny Timms reports.



PENNY TIMMS: Not too deep below the ocean's surface, change is afoot.



Water temperatures are rising, so too is ocean acidification, and those changes are triggering a chain reaction.



Ocean acidification is a consequence of excess carbon dioxide in the atmosphere. The oceans have absorbed large quantities of CO2, which has caused changes in the chemistry of surface sea water.



Craig Humphrey is from the Australian Institute for Marine Science, based in north Queensland.



CRAIG HUMPHREY: Look there's obviously changes in ocean acidification, and temperature. And what's likely to happen is that there'll be different sensitivities of organisms to these changing water quality parameters. What it probably means is that we're going to get changes in communities, so, there may be reefs in the future, but they'll look very different to what they do currently.



PENNY TIMMS: He's the operations manager of the multi-million-dollar national sea simulator.



It's a machine that allows scientists to manipulate environments in an enclosed space, so that they can predict how oceans and organisms are going to react to pressures like climate change.



CRAIG HUMPHREY: At the moment, we're still constructing a lot of those experimental systems, but the idea is to move experimental science forward and, in a way, attract those researchers to the Sea Sim. Hopefully, the idea is that they'll be running experiments in the sea sim that they may not be able to run elsewhere.



PENNY TIMMS: Of particular note is the relationship between rising sea temperatures and ocean acidification.



Many scientists had thought that the combination of the two accelerated the rate and severity of coral bleaching.



Now, that's been debunked.



KATHARINA FABRICIUS: Our study has confirmed that is not the case, corals are very sensitive to thermal bleaching. But ocean acidification is not making it, fortunately, worse for the corals. So, that was unexpected and it helps with predicting how coral reefs will fare in the future.



PENNY TIMMS: That's Katharina Fabricius, one of the research scientists who has been leading the study.



It was carried out in two parts: the first within the national Sea Simulator; the second part of the study was conducted in waters off Papua New Guinea.



She says the discovery will help scientists better shape their future research and their work to preserve the environment.



Though, she says the discovery is bitter-sweet, because oceans are now 30 per cent more acidic than during pre-industrial times.



And while that may not be accelerating coral bleaching, it is changing the ocean's chemistry and threatening the long-term viability of the world's largest living organism - the Great Barrier Reef.



KATHARINA FABRICIUS: Corals are becoming more and more stressed from accumulative pressures of warming oceans and ocean acidification, in combination with the water quality. At this stage, the outlook for the Great Barrier Reef is not great. The reef has lost half of its coral cover in the last 28 years.



At this stage, all we can do is identify what are the main stresses for the coral reef, where are the main regions that are most vulnerable to the stresses, and therefore helping managers to priorities management actions to make sure the reef will be around in 50-100 years' time.



PENNY TIMMS: Do you think it will be around in that time?



KATHARINA FABRICIUS: At this stage, the pressures are greater than the capacity of the reef to recover.



I think there's a lot of scope to improve local and regional management actions, in particular improving water quality has shown to help corals buy some time, to deal with the warming conditions.



MARK COLVIN: Katharina Fabricius ending that report from Penny Timms.