“When parents are exposed to an increase in water temperature, we found that their offspring improved their performance in these otherwise stressful conditions by selectively modifying their epigenome,” said Prof Philip Munday, senior author of a new study by Australia’s ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University, and the King Abdullah University of Science & Technology (KAUST).

“Modifying their epigenome” refers to subtle chemical modifications in the fish’s DNA responsible for signalling genes to be switched on or off. Such alterations can be caused by factors such as heat stress, disease or famine.

When both parent and offspring fish were subjected to the same raised water temperatures, the researchers observed epigenome changes that enhanced the next generation’s ability to cope with the new, warmer temperatures.

“We reared spiny chromis damselfish, a common Indo-Pacific reef fish, for two generations under three different water temperatures, up to 3 degrees Centigrade warmer than current-day ocean temperatures,” explained co-author Prof Timothy Ravasi of KAUST.

“The next generation appeared to be advantaged by parental exposure to elevated temperatures.”

The offspring’s altered genetics, or “acclimation”, allowed them to maximise oxygen consumption and energy use, making them better able to tolerate warmer water.

“Acclimation may buffer populations against the impacts of rapid environmental change and provide time for genetic adaptation to catch up over the longer term,” said Prof Munday.

The authors noted that while this adaptation was good news for reef fish, the decline of their coral habitat through climate change would continue to be an over-riding concern for their survival.

Their study is published in Nature Climate Change.

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