The corals that are the most widespread and best at building reef systems may be the most vulnerable to the impacts of climate change, according to an international team of researchers from Australia, the Netherlands, Germany, Italy, the US and the UK.
In a study published today in Science Advances, the researchers examined the fossil history of corals, as well as global ocean conditions including temperature and sea level, from more than 60 million years ago.
A type of corals called staghorn coral started becoming major contributors to reef building about 1.8 million years ago, according to John Pandolfi, a scientist from the ARC Centre of Excellence for Coral Reef Studies at the University of Queensland. “And coral reefs have been so successful ever since then due in part to its ascendance — indeed, reefs grow most rapidly when staghorns are the dominant reef-building corals,” he said in a statement.
Staghorn corals are the predominant species found in reefs in the Great Barrier Reef off the coast of Australia, and throughout the Pacific, and in the past have been the most resilient coral species to withstand changes in the ocean environment.
The corals also play an important role in maintaining the overall health of reef systems, lead author of the paper Willem Renema from the Naturalis Biodiveristy Center in the Netherlands said in a statement. “Staghorn corals contribute strongly to the structural complexity and three-dimensionality of reefs,” he said. Aside from the reefs themselves, staghorns also “play an important role in the ecosystem services delivered by coral reefs” such as “coastal protection and providing habitat for reef-associated biodiversity,” he added.
Now, however, staghorn corals are declining rapidly worldwide due to numerous factors like oceans becoming warmer and more acidic, as well as factors like overfishing and pollution.
Today’s study adds to growing research on coral reefs’ struggle with warming oceans. Earlier this week, a separate study found that nearly 93 percent of the Great Barrier Reef is suffering from coral bleaching — a process by which corals shed the algae that live on it and keep it alive — likely due to warmer waters driven by climate change and El Niño.
Scientists are now trying to figure out why some corals survive bleaching events and other changes, in the hopes of figuring out how strategies to help corals survive an ever warmer ocean environment and to identify potential mitigation tactics humans can take.
Despite the abundance of bad news for coral reefs, one bright spot was the recent discovery by scientists from the Scripps Institution of Oceanography at the University of California, San Diego of some healthy reefs in a remote islands in the Central Pacific that have not been impacted by human activity.
Scientists have identified some actions that we can take to help endangered. “Relieving local pressures on staghorn corals — for example, by improving water quality — helps increase their resistance to thermal stress from climate change,” Pandolfi said. “So by managing local anthropogenic stressors such as sediment runoff, dredging, and other sources of pollution, we can insure that these corals will be at their best when confronting global warming.”