Two crucial coral reefs in UAE waters are showing signs of recovery from bleaching in a boost for the environment, a study has shown.
When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white. Corals can survive a bleaching event, but their death can lead to diminished coastal protection and reduced fish stocks.
A major bleaching in 2021 left corals in the waters of Sir Bu Nair island and Khor Fakkan in Sharjah vulnerable.
But findings from monitoring carried out since then provide some optimism, as regrowth has been noted.
Experts believe the expansion of crucial protected areas, working with divers to build awareness of corals and other management efforts can turn the tide and further aid the recovery.
“As long as conditions return to normal and we give them time to recover, they can recover," John Burt, professor of biology at NYU Abu Dhabi and one of the paper’s authors, told The National. "We're hopeful that things are going in the right direction.”
Sir Bu Nair island lies about 70km offshore in the Arabian Gulf, in a marine protected area, while the reefs of Khor Fakkan are on the UAE’s Gulf of Oman coast.
The corals found at these two locations are known as table corals (Acropora) and used to be dominant in the region. But increasing heat, along with other stresses such as pollution, mean they are the first to be knocked out and there are only pockets left.
Prof Burt said table corals are important as they grow fast, build reefs quickly and are quite complex in shape, meaning that they are attractive to fish.
A renowned expert on corals, he estimates that about 75 per cent in total coral at Sir Bu Nair and 63 per cent at Khor Fakkan were lost. These were almost exclusively table corals, he added.
It is believed there has been a 15 to 20 per cent increase in live coral since the bleaching event but more monitoring is being conducted.
Table corals had survived at these two locations because the reefs were surrounded by slightly deeper water. When the tide goes in and out, the colder, deeper water chills the reef giving corals a reprieve.
While cautioning the severity of the event should not be underestimated and there had been a shift towards more heat-resilient species dominating the community in the wake of it, Prof Burt said some table corals had recovered and “these are among the fastest growing species that we have around here” meaning they could become dominant again.
The development was outlined in a paper published in Diversity - a peer-reviewed, open access journal – in August. It showed how a biodiversity assessment led by NYUAD's Mubadala Arabian Center for Climate and Environmental Sciences in collaboration with a faculty member at the American University of Sharjah and with the support of the Sharjah Environment and Protected Areas Authority (EPAA) turned its focus to bleaching when researchers saw what was happening.
What causes bleaching?
The Arabian Gulf is one of the world’s hottest seas and scientists believe climate change is making extreme warming events more common.
Prof Burt said the 2021 episode was unique for its severity and the fact it extended across the region. “We had sea temperatures that exceeded 37°C, which is unusually extreme. Normally we'll hit a maximum of 35.5°C most summers," he said.
“That's extremely hot compared to global standards. The Great Barrier Reef would be heavily bleached at 32°C, and we were already well above that."
If cooler temperatures do not return to normal, bleached corals will die. Typically it takes ten years for full recovery after bleaching.
Prof Burt said the recovery in Sharjah's waters was being aided by relatively cooler conditions this year.
What can be done to help?
Coral reefs occupy less than one per cent of the ocean floor yet they are home to more than 25 per cent of marine life, the UN Environment programme has said.
In a speech delivered in June, Inger Andersen, executive director of the UN Environment Programme, said more than 80 per cent of the world’s coral reefs have experienced coral bleaching conditions for almost two years.
But the good news is there is much that can be done to help. Prof Burt pointed to developments such as how experts on the Great Barrier Reef place coverings over the reefs to limit the amount of light that hits it.
Other solutions could include “biobanking” – saving corals during hot summers so genetic resources are not lost.
Prof Burt also praised the “very good management and conservation practices” that have been put in place by Sharjah, pointing to the marine protected area around Sir Bu Nair.
“The protected area is very well enforced,” he said. “The general public is not allowed to visit Sir Bu Nair to go fishing or diving, for example. [The Sharjah authority] also put in mooring buoys in Khor Fakkan so nobody's dropping anchor any more.”
Working with the diving community
Prof Burt said there is room for expansion, adding that it is important to work with the diving community. Novice divers, he said, can tip the tops of corals in what is known as “fin-strike”.
“Corals are incredibly sensitive,” he said. “It's only about two millimetres of the surface of a coral that's alive, and it is a soft, jellyfish-like material. If you hit it with a fin, you are damaging it.”
Managers could limit diving on these reefs and also encourage local dive operators to become certified initiatives such as Green Fins.
“My biggest recommendation would be that we engage with the various diving-related associations and companies that are operating on the east coast of the UAE to ensure that new divers are trained in an area where coral reefs don't exist.”
The shoots of recovery also come as efforts continue across the UAE and region to preserve vital reefs.
Abu Dhabi, for example, has revealed plans to plant millions of coral colonies. There is also work under way to collect corals and safeguard them for restoration, alongside work on selective breeding to create heat-tolerant corals.
“We can try to ensure that the next generation of corals that are restored to reefs are the most hardy available,” said Prof Burt. “Watch this space.”
