Ningaloo reef ‘can survive hotter ocean’

The Ningaloo Reef could withstand a massive rise in sea temperature that threatens to wipe out 90 per cent of the world’s coral reefs because of cooling ocean currents that circulate off the WA coast.

New scientific research has pointed to a worst-case scenario 4C rise in ocean temperatures as soon as 2050, with WA waters already heating up faster than the rest of Australia.

But CSIRO science fellow Beth Fulton, in Perth to present her findings from ecosystem modelling to the international Frontiers of Science marine conference, said the currents off Exmouth could act as an air-conditioner for the world-famous reef.

“Temperature-wise it looks like the reef will be buffered because there is a deep cold-water plume that gets sucked up seasonally and protects the reef, a bit like having an air-conditioner that it can throw on to save itself from massive bleaching,” she said.

“But we don’t know for sure because the ocean acidification, which is also rising rapidly, potentially makes the reef a lot more brittle.”

Dr Fulton described the research as a mixed bag for WA once temperatures rose and acidification took hold, with some of the biggest ocean temperature changes in Australia happening off the west coast.

The cooling currents will not save North-West beaches that are predicted to be wiped out by sea-level rises.

“Sea-level rise is very likely to affect the beaches up there – the work suggests we could lose all of the major tourist beaches,” Dr Fulton said.

The make-up of the Indian Ocean off WA would also become unrecognisable with tropical fish species, including emperor and snapper species, potentially found off Perth.

“It’s not necessarily all going to be bad,” she said. “Some species will find benefits, they will expand their range, they’ll be more productive . . . often fast growing species that like warm waters will move further south.

“But some of the more cold water species are finding it hard to find anywhere to live . . . they run out of habitat so they face problems.”
There was even potential for whale sharks to move further south during their annual stay off WA. Dr Fulton stressed the science behind her modelling was ever changing and had to be constantly monitored.

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