Researchers from the University of Southampton and New York University Abu Dhabi have discovered a species of algae in the Persian Gulf that could protect coral reefs from global warming.
Their report, recently published in the journal Scientific Reports, examines a “thermotolerant” species of algae known as Symbiodinium thermophilum. This algae can survive maximum temperatures of 34-36℃ and annual temperature fluctuations of up to 20℃.
Temperature change and fluctuation is a major problem facing corals worldwide. Sudden or significant drops in water temperature can distress coral and cause them to expel the symbiotic algae that keep them healthy and strong. Though they often look like nothing more than pretty underwater rocks (and indeed, their skeletons are made of limestone), coral are living organisms that sustain a vast array of marine life. According to the National Oceanic and Atmospheric Administration (NOAA), coral reefs cover less than one percent of the ocean floor but support approximately 25 percent of all underwater life – including over 4,000 species of fish.
Most species of coral form symbiotic bonds with algae, which feed off the light of the sun and produce sugars that the coral eats. In return, the algae is provided with shelter and nutrients of its own. However, this delicate relationship can be disrupted by as little as one degree Celsius of temperature change. A severe El Niño event between 1997 and 1998 resulted in the destruction of 15 percent of the world’s corals.
When a coral expels its algae, it typically survives for up to eight weeks before dying. As it does so, its color fades and the coral “bleaches.”
Even before 2014 was officially declared the hottest year on record by the JMA, NASA and NOAA, a coral bleaching off the coast of Florida had many scientists worried about the fate of corals in the rest of the world. Because the oceans are currently absorbing roughly 90 percent of the planet’s heat, coral bleaching events are expected to become more frequent and severe in this century.
Researchers were studying the S. thermophilum algae off the coast of Abu Dhabi to learn how it survived in the warmest coral reef habitat in the world.
“Understanding how corals survive under the extreme temperatures in the Gulf will give us important insights into the ability of reef corals to handle the heat stress, which is threatening their survival in the oceans that are warming up in response to climate change,” Jörg Wiedenmann, professor of biological oceanography and head of the coral reef laboratory at the University of Southampton, said in a statement.
One scientific study says that the world is on track to warm by as much as 4.6℃ by 2100. If that comes to pass, most corals may die off in the coming century – except for those with the S. thermophilum algae.
“It gives hope to find that corals have more ways to adjust to stressful environmental conditions than we had previously thought,” said Wiedenmann.
Of course, corals don’t only have heat to worry about. As countries continue to pump out carbon dioxide, around 25 percent of it is being absorbed by the oceans and turned into carbonic acid. Scientists have stated that the ocean is now acidifying at the fastest rate in 300 million years, endangering corals’ limestone skeletons and weakening the shells of crustaceans and other animals.