Coral bleaching occurs due to a breakdown in coral-algae symbiosis, caused by stressful environmental conditions, such as extremes of light, temperature, or salinity. These environmental stressors result in the expulsion of algae that live in coral tissue, causing coral to appear bleached — they may even die due to starvation.
Bleaching can occur at one degree above the summer maximum temperature, approximately 30 to 31 degrees Celsius in regions such as the Great Barrier Reef and the Caribbean. In the Arabian Gulf, however, coral are exposed to summer temperatures up to 36 degrees Celsius — yet they somehow survive.
As ocean temperatures are predicted to increase one to three degrees in the next 100 years due to climate change, reefs elsewhere are expected to bleach every summer, which will lead to the death of many coral colonies. If this continues to happen every year, coral reefs may cease to exist.
Edward Smith, a postdoctoral associate at NYU Abu Dhabi's Marine Biology Laboratory, studies coral biology; his main goal is to discover what allows Gulf coral to survive under extreme conditions that would kill other coral. "Despite these thermally tolerant corals being unique in the global system, they haven't really been well studied, and that's largely because of where they are based," Smith said. "The biggest selling point of the Gulf is that it is a natural aquarium in which to study climate change in corals."
Through extensive fieldwork and laboratory experiments, Smith, along with Emily Howells, a postdoctoral researcher at NYUAD, conducts in-depth studies that address the molecular and the physiological aspects of corals in the Gulf. They are trying to learn if corals in the Gulf are genetically different from other populations, or if there are environmental conditions in the Gulf — such as light, sediments, or the salinity of the seawater — that allow Gulf coral to survive this extreme environment.
Furthermore, if Gulf coral are discovered to be genetically different, there are more questions to ask: What are the Gulf coral doing differently than others? How long has it taken Gulf coral to acquire these abilities to survive high temperatures? Smith explained: "What we can learn from the coral populations here will help us predict what is going to happen in the future with climate change, and it can also help guide future management of the reefs." His work may help keep tomorrow's coral reefs as colorful as they are today.