According to an EPFL team, corals from the Gulf of Aqaba and their symbiotic partner, algae and mycobacteria, are particularly resistant to heat. According to the researchers this protects them from global warming for 100 or 200 years.
Even in the most optimistic scenarios, most of the coral ecosystems in the world’s oceans, from Australia to the Caribbean, to the Maldives would have either disappeared or would be under strict stress by the end of the century. In Lausanne (EPFL) in a press release.
Rising sea temperatures reach their tolerance limits, they lose their main allies, the unicellular algae, which, in exchange for a safe haven in the structure of their trees, give them the nutrients they need for their food by photosynthesis Provide.
Algae have a series of pigments that decorate corals with their beautiful colors and it is their disappearance that causes the famous phenomenon of bleaching. However, in this painting with a monochrome future, the corals of the Red Sea retain their color.
‘A real hope’
‘We know that the northern Red Sea cores in the Gulf of Aqaba are particularly resistant to high temperatures. But we wanted to study the molecular mechanisms of this heat resistance as a whole, ‘the study’s first author, Romain Savary, told in a press release.
The results published in the PNAS Journal are clear: corals, as well as algae and mycobacteria, resist an eyelid without batting the average temperature higher than 5 degrees that they are used to. However, despite the severity of ongoing climate change, the rise in temperature in the Red Sea waters is unlikely to exceed this limit by the end of this century.
“It offers real hope for the preservation of at least one important coral ecosystem,” says Anders Meibom, director of the Laboratory of Biological Geochemistry (LGB) at the EPFL.
As if nothing ever happened
Researchers are likely to subject these corals to a range of temperature levels in the coming decades. While the monthly average maximum water temperature in the region is around 27 degrees, the corals have been heated to 29.5 ° C, 32 ° C and 34.5 ° C. Short term, for 3 hours, and long term, for one week.
During and after the period of heat stress, researchers measured the expression of the gene in the coral and its symbiotic algae as well as the composition of the resident bacterial community.
‘The main finding is that we have realized that these corals still remain well below the tolerance threshold that their molecular mechanisms can withstand, which saves them up to 100, 200 years of temperature rise.’ .
In any case up to 32 ° C, we were able to measure that they recovered without a molecular sequence and were shortened to long periods of heat as well as to their symbiotic partners, ‘the researcher says.
Genetic analysis of samples, the first on this scale, shows how this hyper-resistant coral reacts at the most fundamental level, that is gene expression. This sets a benchmark to define ‘Super Coral’.
The study also highlights the fact that it is a veritable concert of gene expression that bases this superpower on the corals. This is sufficient to fulfill the expectation of genetically manipulating corals of less resistant corals.
For example, to use the Red Sea corals to reopen the Great Barrier Reef, it is hardly possible. ‘Coral is highly dependent on its environment and can generally be adapted elsewhere with only a long natural colonization. In addition, the Great Barrier Reef is Italy-shaped, making it impossible to artificially reintroduce it, ‘says Anders Meibom.
This work was made possible by two unique devices, the Red Sea Simulator, installed by the University of Marine Sciences Institute in Elliott, Israel, and an American Mobile Bleaching Diagnostic System (Coral Bleaching Autonomous Stress System, CBASS).