Crossbred corals beat the heat on the great barrier reef

By Karl Gruber 26 June 2015
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In a good news story for the Great Barrier Reef, some corals seem to be able to pass on heat-tolerant genes

MIXING UP THE genetic pool of some reef-building corals may help save them from raising sea temperatures, a new study has found.

Australian and American researchers cross-bred the branching coral, Acropora millepora, from samples located at different reefs in Australia. Individuals from Princess Charlotte Bay, on the upper north side of the Great Barrier Reef, were mated with individuals from Orpheous Island, some 540km south.

These two locations have significant differences in water temperature, suggesting that some populations of this coral species harbour genes that help the corals deal with higher water temperatures.

“This discovery adds to our understanding of the potential for coral on the Great Barrier Reef to cope with hotter oceans,” says Dr Line Bay, an evolutionary ecologist from the Australian Institute of Marine Science in Townsville and joint senior author on the study.

A close-up of adult coral (A. millepora). Credit: Mikhail Matz, The University of Texas at Austin  

Coral able to pass on heat-tolerant genes

Previous research has shown that many coral species can interbreed over thousands of kilometres, potentially involving populations that have adapted high sea temperatures. However, it has been unclear whether the heat-tolerance of some of these corals was a trait that could be inherited.

In their experiments, scientists show that larvae exposed to heat stress is up to 10 times more like to survive if one of their parents comes from a warmer, lower-latitude location, suggesting there is a heritable component to heat resistance.

The findings may hold promise for developing novel conservation approaches. “Averting coral extinction can begin with something as simple as exchange of coral immigrants across latitudes, which will happen naturally through larval dispersal but can be jump-started by humans moving adult corals,” says Mikhail Matz, a professor of integrative biology at the University of Texas at Austin and co-lead author.