"Is it just me, or is it getting hot in here?" is what many of the world's fish are probably wondering right about now, as the effects of climate change have seen ocean temperatures rise to potentially deadly levels. But some species seem better equipped than others to cope with rising temperatures, and now researchers from Australia's James Cook University (JCU) have finally figured out why.

To investigate why some fish are able to acclimatise to warmer temperatures, the team looked at how reef fish's genes responded over time to projected future ocean temperatures, rearing the animals through multiple generations in purpose-built facilities designed for the study.

"Some fish have a remarkable capacity to adjust to higher water temperatures over a few generations of exposure," one of the JCU researchers, Heather Veilleux, said in a media statement. "But until now, how they do this has been a mystery."

By sequencing the RNA molecules of adult tropical reef fish, the researchers found 53 key genes involved in long-term, multi-generational acclimation to higher temperatures. "By matching gene expression to metabolic performance of the fish, we were able to identify which genes make acclimation to higher temperatures possible," said Philip Munday, a co-author of the study.

The findings of the study, which was a collaboration between JCU's ARC Centre of Excellence for Coral Reef Studies and researchers at the King Abdullah University of Science and Technology in Saudi Arabia, will bolster future research efforts and aid scientists' understanding of the genetic traits that affect marine conservation efforts.

"Understanding which genes are involved in transgenerational acclimation, and how their expression is regulated, will improve our understanding of adaptive responses to rapid environmental change and help identify which species are most at risk from climate change and which species are more tolerant," said Veilleux.

The research is published in the journal Nature Climate Change.

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