Researchers at the Bermuda Institute of Ocean Sciences are looking for ways to help corals survive warming waters.

The BIOS Currents newsletter said that the Enhancing Coral Resilience Against Climate Warming project, also known as Encore, had entered its second year.

The collaboration between BIOS and Arizona State University is intended to learn more about how corals develop a resistance to temperature changes and pass it along to future generations.

Yvonne Sawall, marine benthic ecologist and a principal investigator with the project, said: “Can we make reef-building corals stronger? That is what the Encore project is about.

“We’re trying to train them to become more thermally resistant.”

A 2020 United Nations report found a loss of about 14 per cent of the world’s coral between 2009 and 2018 was primarily due to recurring large-scale coral bleaching events, which are linked to marine heatwaves.

However, researchers at BIOS had shown that adult corals which survive environmental stresses produce offspring that are “preconditioned” to survive in new environments.

The Encore project is intended to build of previous work and examine strategies to help coral populations become more resistant to warmer waters.

This summer, Encore explored whether corals that are exposed to and survive heat stress last year retained a higher resiliency by exposing them to another heat stress this year.

Researchers on the team have also started experiments on coral larvae to determine if early exposure to thermal stress will allow them to be more adaptable once matured.

As of mid-August, brain coral specimens had yet to spawn, but experiments were under way with an “unexpectedly prolific” spawn of mustard hill coral.

Brett Jameson, a postdoctoral scientist with the project, said that the team had started with two groups of mustard hill coral larvae and exposed one to warmer waters (30C) and the other to ambient temperature water (28C).

They were then all transferred to a “common garden”, which was kept at ambient temperature.

After two weeks, the corals were again divided into two groups with half exposed to warmer waters.

“In this way, the study mimics a potential natural scenario in Bermuda, where an early summer marine heatwave is followed by another more intense one in August,” the newsletter writer said.

“This time, half of the recruits previously exposed to heat stress were exposed again, as were half that had remained in ambient temperature in the first phase.

“Likewise, half the ambient group in phase one remained in ambient conditions during the second phase, while half were subjected to warmer water in this round.”

Mr Jameson said: “We will test if the previous stress has been beneficial or detrimental and if we can distinguish between the effects at different levels of coral development.”

The team’s work is scheduled to continue in 2024 as the scientists investigate further if heat-resilient specimens are passing those traits on to their offspring.

Ms Sawall noted that specimens being collected today were already more thermally resilient than previous generations of coral because of natural selection and that scientists had found that the algae hosted by coral had adapted to handle more heat.

“There is hope that through adaptation of the algae, they may actually be able to adapt fairly quickly,” Ms Sawall said. “At least some of them. That’s the hope.”