Scientists in Abu Dhabi are stress-testing corals to find the species most resilient to extreme heat which could be used to repopulate the UAE's seabeds.
The study involved colonies being placed in gradually rising water temperatures with their level of heat-tolerance recorded.
The work, carried out by team of scientists from NYU Abu Dhabi’s Mubadala Arabian Centre for Climate and Environmental Sciences (Mubadala Access), could play a leading role in the battle against climate change, said John Burt, a professor of biology at NYU Abu Dhabi.
Hundreds of corals were tested directly in the field on reefs across both coasts of the UAE.
“The UAE is home to corals that already survive in the world’s warmest seas, but climate change is pushing even these hardy species to their limits,” said Prof Burt.
While the researchers are unable to release full details until their findings have been published in a scientific paper, Prof Burt said that the most heat-tolerant UAE corals, found in Ras Ghanada north-east of Abu Dhabi city, and Delta Buoy, 25km offshore from the capital, could deal with temperatures “several degrees Celsius” higher than any other corals analysed so far.
The heat is on
In the UAE study, species called brain corals and knob corals across nine reef sites from western Abu Dhabi to Fujairah were compared, demonstrating differences across species as well as across the country.
The researchers will reveal full details, including further information on which corals are the most heat tolerant, when they officially publish their findings at a later date.
Coral fragments were tested using the Coral Bleaching Automated Stress System (CBASS), which consists of small water tanks where the temperature is gradually raised. The researchers then assessed the organisms’ responses, a process that took 18 hours.
The scientists dived into the waters and removed a thumbnail-sized piece of coral using an drill. They kept each fragment alive by immersing it in water until they were back at shore.
“Once onshore, we immediately put the fragments into the CBASS stress assay system (which we would have already set up and prepared the night before),” Prof Burt said.
“These are functionally highly standardised, insulated and temperature controlled aquaria with specialised lighting where we can keep conditions highly controlled as we run the experiment.”
While the experiment was running, the researchers measured the corals’ physiological responses and carried out visual assessments while the experiment was running.
At the end, to enable the scientists to carry out later biochemical and genetic analysis, each fragment was flash frozen in liquid nitrogen.
Flash freezing involves freezing something quickly to an extremely low temperature so that ice crystals do not form. Liquid nitrogen is used for flash freezing because, with a boiling point of -196°C, it is extremely cold.
Across each site, corals were tested in water at the average monthly maximum temperature, and at temperatures that were 3°C, 6°C and 10°C hotter than this.
Mapping out the future
“So, for example, Drinkle Shoal in western Abu Dhabi had warmest summer temperatures (34.9°C mean monthly maximum), meaning we ramped up the hottest tank to 44.9°C,” Prof Burt said.
“This was the hottest temperature CBASS has ever been run at in the world, as our normal summer temperatures are the hottest on Earth.”
Drinkle Shoal, which is marked on nautical maps, is an area between Delma Island and Sir Baniyas Island.
Mubadala Access undertook the work with the Environment Agency Abu Dhabi, Fujairah Environment Authority, Ras Al Khaimah Environment Protection and Development Authority and Sharjah Environment and Protected Areas Authority.
While UAE corals can survive in some of the world’s warmest seas, scientists are concerned that they are being pushed to their limits by climate change.
Many corals off UAE coasts have suffered bleaching, in which extreme high temperatures cause them to expel the algae that live inside them. While corals may recover from bleaching, as has been seen in reefs off Sharjah, in extreme cases reefs are killed.
Research published last year suggested that most corals in the Arabian Gulf could be wiped out this century because temperatures are rising.
Other work has found that when reefs are affected by extreme temperatures, more heat-tolerant types that are better able to cope with future episodes of warming are left behind, although these may not support as wide a range of other organisms.
In a statement, Maitha Mohamed Al Hameli, director of Environment Agency Abu Dhabi's marine biodiversity division, said that the organisation was “committed to advancing science-based solutions that protect our most vital ecosystems”.
“By rebuilding reefs with heat-tolerant corals, the initiative not only restores structure and biodiversity but also strengthens the long-term resilience of Abu Dhabi’s coral ecosystems in the face of climate change,” she said.
Asila Abdullah Al Mualla, director general of the Fujairah Environment Authority, described the initiative as “a significant step towards ensuring the continued flourishing of our coral reefs” and the ecosystems they are part of.
