The Great Barrier Reef in Australia is not healing after it experienced a series of severe coral bleaching induced by global warming.
According to a new study, the back-to-back bleaching events that devastated the UNESCO World Heritage Site in 2016 and 2017 has affected its ability to recruit new corals. The findings suggest that the largest collection of coral reefs in the world unlikely to fully recover anytime soon.
New Coral Recruitment Down In 2018
Scientists at the ARC Center of Excellence for Coral Reef Studies monitored the death and birth of corals in the Great Barrier Reef after the 2016 and 2017 bleaching events. The team revealed in the study published in the journal Nature that new coral recruitment in 2018, a year after the second bleaching event, was 89 percent lower than historical levels.
"We never thought we would see disturbance on a scale to affect recruitment to this extent," stated Andrew Baird, co-author of the study.
The Great Barrier Reef located off the north-east coast of Australia is dubbed as the biggest living structure on Earth. It covers 344,400 square kilometers and is home to a wide variety of marine plants and animals, some of which cannot be found anywhere else in the world.
The site has only experienced four mass bleaching events recorded in history and all of them happened in the past two decades. The back-to-back disasters in 2016 and 2017 caused many adult corals to die.
While coral reefs can survive bleaching events, it would take years for them to recover. Scientists estimate that the production of baby corals to return to normal in about five to 10 years, but only if there will not be another bleaching event in the next decade.
The fate of the Great Barrier Reef is looking grim. The UNESCO's climate models predict that bleaching events will become more frequent if the high emission of excess greenhouse gases continues. They warn that bleaching events will occur at least twice in every decade beginning in 2035.
Corals Are Becoming Resilient
The scientists also shared some good news. Evidence suggests that some species of coral are growing more resilient to the impacts of climate change. The team reported that it took much greater heat exposure for the coral reefs to show the same level of damage during the second bleaching event between 2016 and 2017.
"So the reef is now moving rapidly to a new configuration, with a greater proportion of the species that are resistant to bleaching, or that are capable of bouncing back the fastest," added Terry Hughes, director of the ARC Center for Excellence for Coral Reef Studies.
The diversity, however, would be lost. A number of species will be gone if the trend continues.
The study already found that the population of Acropora declined 93 percent in 2018. The branching coral provides most of the reef habitat in the Great Barrier Reef, supporting thousands of other species like clownfish and triggerfish.
