Some corals are adapting to climate change and becoming more tolerant of warmer temperatures, a study has found.

The discovery opens the door to saving threatened coral populations by allowing them to spread their genes.

Scientists crossed corals from Australia’s Great Barrier Reef with others whose home was 480 kilometres further south.

Larvae inherited significantly greater heat tolerance from Great Barrier Reef parents. An Australian mother conferred a five-fold increase in the ability to withstand heat while a father contributed an additional two-fold increase.

The researchers were able to demonstrate that heat tolerance could evolve rapidly with existing genetic variation.

Coral larvae can move across oceans naturally, but humans could also contribute, relocating adult corals to jump-start the process

Mikhail Matz, from the University of Texas, US, said: “Our research found that corals do not have to wait for new mutations to appear. Averting coral extinction may start with something as simple as an exchange of coral immigrants to spread already existing genetic variants.

“Coral larvae can move across oceans naturally, but humans could also contribute, relocating adult corals to jump-start the process.”

Corals worldwide have been badly damaged by rising sea surface temperatures. Warming waters have been linked to bleaching, a process that kills coral by wiping out the symbiotic algae they depend on for food.

Reef-building corals from the northern Pacific Ocean and Caribbean are similar to those used in the study, published in the journal Science.

The scientists believe coral in these locations may benefit from efforts to protect those that are the most heat tolerant.

“This is occasion for hope and optimism about coral reefs and the marine life that thrives in them,” said Matz.