Marine heatwaves more devastating to coral reefs than previously thought: Australian research

Rodiano Bonacci
Agosto 10, 2019

Researchers from Australia, the United Kingdom and the U.S. studied the impact of global warming in Australia's Great Barrier Reef and published their findings on Friday in the Current Biology journal.

Marine heatwaves, which have become more frequent, intense, and have been staying longer, are playing a huge role in coral death, says new research from scientists working at the Great Barrier Reef.

But the new study found that severe marine heatwaves can actually degrade the skeletal structure of the coral, potentially killing the organisms in a matter of days or weeks.

Dr Richardson added that the team had documented, for the first time, that severe heatwaves were causing "almost instant mortality of corals". The degradation also puts at risk many other sea creatures that live in the sea coral.

However, the new study-conducted by researchers at the University of New South Wales Sydney, the University of Newcastle, the University of Technology Sydney, James Cook University, and the National Oceanographic and Atmospheric Administration (NOAA)-heightens concerns about the future of coral reefs in a warming world.

"The water temperatures are so warm that the coral animal doesn't bleach - in terms of a loss of its symbiosis - the animal dies and its underlying skeleton is all that remains", she said.

In this study, the team now find that severe marine heatwaves not only trigger bleaching events as we have known them - a breakdown of symbiosis - but in fact can lead to heat-induced mortality of the coral animal itself.

Researchers suggest that "severe heatwave-induced mortality events" should therefore be considered a separate phenomenon to coral bleaching, and one which causes more damage.

Though the study generated alarm, the researchers expressed hope that it will spur public outcry for policymakers to pursue bolder efforts to combat the climate crisis-and, specifically, protect coral reefs, particularly considering the anticipated consequences of inaction.

"We are just going so far beyond what's normal". Dr. Ainsworth explained, what they see here is that when the coral tissue dies, it falls and breaks away from the skeleton. This discovery fits into this category.

"As we begin now to understand this impact, the question is how many more of these "unknown unknowns" might there still be that could bring faster and greater damage to coral reefs from climate change".

Commenting on the research, Dr James Guest from Newcastle University in the United Kingdom, who has been studying coral reef habitats for more than 15 years, said: "It's hard to know just how much we have to keep saying that this is a big problem before policy-makers decide to do something about it".

As well as being vital habitats for marine life, coral reefs are vital to people in coastal communities, who depend on them for fishing, tourism and beach protection.

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