Climate change fuels the collapse of baby corals in the Great Barrier Reef

Is history It was originally published by HuffPost and reproduced here as part of the Climate table collaboration.

The deadly consecutive whitening events that struck the Great Barrier Reef of Australia in 2016 and 2017 led to a collapse in the recruitment of new corals, which severely affected the ecosystem's ability to recover from the devastation.

That's according to a new study published Wednesday in the journal Nature, which found that the number of juvenile corals that settled throughout the Great Barrier Reef in 2018 was 89 percent lower than the historical averages before major whitening events . The loss of so many mature adults during the heat waves of the ocean driven by climate change left the ecosystem, the largest life structure on the planet, largely unable to recover.

The report highlights the difficult situation of corals in a warming world.

Along with a general shortage of descendants, the study documents an alarming change in the composition of coral larvae. Deer antler corals and table corals, the species that provide most of the habitat on the reef, produced fewer offspring than less common stony corals. It is a change that probably reduces the diversity of the reef, which leaves it less resistant to future warming.

"The way the Great Barrier Reef behaves has changed," Terry Hughes, lead author of the study and director of the ARC Center for Excellence in Coral Reef Studies, said by telephone. "The mix of adult species is different. The mix of baby species is radically different. And the way it is interconnected has changed. "

The Great Barrier Reef has been affected by four mbadive whitening events since 1998. Almost 30 percent of the reef died alone in 2016. Scientists at the time described the damage in places like Lizard Island, in the northern part of the reef, as "so sober"And he noticed that" something like a train crash "was about to happen.

Hughes said that under normal conditions, it would take approximately 10 years for coral recruitment to recover.

"The adult population will have to come back together," he said. "There is a shortage of large and highly productive corals in the system, it will take a while to regroup so that larval production returns to normal levels."

But with the forecast of climate change to cause more frequent extreme heat waves, Hughes said that "the big question is whether we have the luxury of a decade for the recovery to fully develop."

Coral bleaching is a phenomenon in which corals stressed by heat turn white after they expel their algae, which provide most of the energy of the coral polyps. If they are not allowed to recover free of stressors, corals may perish. The most recent coral bleaching event, which lasted from June 2014 to May 2017, was the "longest, most extensive and possibly the most damaging coral bleaching event ever recorded," said Coral Reef Watch.

Scientists say that not reducing global emissions of greenhouse gases would mean the loss of reefs around the world. A study supported by the United States published in 2017 predicted that "severe annual bleaching" will affect 99 percent of the world's reefs within the century. The United Nations Intergovernmental Panel on Climate Change warned in a report late last year that the world's tropical reefs could decrease by 70 to 90 percent, with an average global increase of 1.5 degrees Celsius compared to pre-industrial temperatures, the upper limit which is the Paris goal. Climate Agreement. At 2 degrees C, 99% of the reefs could be lost. And the latest federal climate badessment, published by the Trump administration in November, concluded that the loss of unique coral reef ecosystems "can only be avoided by reducing carbon dioxide emissions."

Hughes said the Great Barrier Reef is undergoing rapid change and is in serious trouble, but it is not too late to save it from total destruction.

"He still has a pulse," he said. "I think if we can maintain global warming at 1.5 degrees C, we will certainly have a Great Barrier Reef, but the species mix will be very different from today's."

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