As oceans warm, coral reefs could lose their ecological function

Areeba Khwaja

Climate change poses a serious threat to reef-building corals, but researchers found that corals can adapt to these current events if humans can adapt too.

An international group of 22 researchers published a report on the future of reef-building corals, their ability to adapt to climate change and recommendations for human action. They published their predictions on Sept. 1 in Nature Climate Change. Their career-long research culminated at a workshop in Hawaii last year.

Corals are animals that secrete calcium carbonate to build reefs, according to UT ecologist Misha Matz, who contributed to the paper. Global warming increases carbon dioxide in the ocean, and this acidification breaks down the calcium carbonate in corals, according to the National Oceanic and Atmospheric Administration. Matz added that while global temperatures are rising, corals have the ability to adapt evolutionarily to their environment.

“Climate change doesn’t necessarily mean that corals won’t be able to tolerate the heat,” Matz said. “Across different environments, we can already see that three hundred major reef-building species exist in both hot and cold climates. The question is if we can act in time to make sure these temperatures don’t reach an extreme — which they are.”

Matz said because of their adaptive power, we don’t need to wait for some magical mutation to come along and help corals fight their environment. The world simply needs to make a conscious and collective decision to fight climate change instead.

“The momentum in climate change is so large that even if we stopped all greenhouse gas emissions today, the earth’s climate would still keep increasing for several decades,” said Greg Torda, a postdoctoral research fellow at the Australian Research Center.

Bleaching is another significant threat to corals in addition to global warming, both researchers said.

“(Coral bleaching is) a symptom of severe stress, like a fever,” Matz said.

Bleaching occurs when the symbiotic relationship with coral and algae is broken, which takes away the brownish-red color and leaves behind transparent, white coral skeletons.

“The symbiosis between the coral and its algae is a fragile one — just a few degrees of increase in temperature leads … to the coral getting rid of the algae,” Torda said.

According to Torda, corals will never go extinct, but will no longer be able serve the ecosystem if they become rocks. This process already occurred in the rocky reefs of the Caribbean, which Torda said has less than 5 percent coral cover today.

“Corals provide shelter, food and habitat to myriads of reef species,” Torda said. “If corals are gone, so are these species, and the entire ecosystem collapses. We will lose food provisioning, coastal protection, cultural values, tourism and recreation. It is not the corals that will lose, but us, humans.”

Drastic efforts need to occur in order to make progress, although it is a matter of intention, according to both researchers. One-fifth of the world’s population directly depends on reefs for their livelihood or for the economy, so the effects of coral loss would be detrimental, according to Torda.

“We are pretty much on the border, in terms of time left to act, where we could still turn things around if we did the right thing — which, unfortunately, the current leaders of the world are not doing,” Torda said.