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(Reuters) – Climate change is likely to make reef-building stony corals lose out to softer cousins in a damaging shift for many types of fish that use reefs as hideaways and nurseries for their young, a study showed.

Soft corals such as mushroom-shaped yellow leather coral, which lack a hard outer skeleton, were far more abundant than hard corals off Iwotorishima, an island off south Japan where volcanic vents make the waters slightly acidic, it said.

A build-up of carbon dioxide in the atmosphere is turning the oceans more acidic in a process likely to hamper the ability of creatures such as lobsters, crabs, mussels or stony corals to build protective outer layers.

"Soft coral has the potential to be a winner in coral reefs," lead author Shihori Inoue of the University of Tokyo told Reuters by e-mail of the findings, the first study of likely winners and losers among soft and hard corals.

"Reef communities may shift from reef-building hard corals to non-reef-building soft corals under (carbon dioxide levels) predicted by the end of this century," the authors wrote in Monday's edition of the journal Nature Climate Change.

When it reacts with water, carbon dioxide in the atmosphere can form carbonic acid. That damages hard corals, tiny animals that secrete calcium carbonate to form their stony protective layer.

"When combined with their ability for rapid colonization, soft corals may out compete hard corals in coral reef environments subject to ocean acidification," the scientists wrote.

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