Coral reef bleaching: Heatwaves kill coral reefs far faster than thought

James Marshall
August 10, 2019

Their research showed that while it was previously understood that coral bleaching can lead to a break down of symbiosis, marine heatwaves can lead directly to heat-induced mortality of the coral animal as well.

This bleaching and skeletal decay risks the lives of the many other sea creatures call the coral framework home.

As per new research carried on by the University of New South Wales (UNSW), the University of Technology Sydney, the University of Newcastle, the US NOAA, and James Cook University, ocean heatwaves due to global warming affect coral reefs worldwide more than scientists expected.

Coral reefs may be even more susceptible to marine heatwaves than previously thought, with a new research revealing on Friday that not only is coral affected by bleaching, but higher water temperatures can be directly fatal to the coral as well. These increasingly severe thermal conditions are causing an unprecedented increase in the frequency and severity of mortality events in marine ecosystems, including on coral reefs. They suggest that severe heatwave-induced mortality events should therefore be considered a distinct biological phenomenon, with more direct damage different from coral bleaching.

The findings revealed that extreme heat waves go beyond just causing a process known as "bleaching", a coral-related event that occurs when water temperatures get so warm that they expel algae from their tissues, forcing them to turn white.

"We are just going so far beyond what's normal". The heat kills the tissue on the coral reefs, leaving them vulnerable to microbes which then cover the stripped skeletons, dissolving them within as little as a few days.

"It confirms that we are on a trajectory where heatwave events and heat stress is becoming so severe it's beyond the capacity of the ecosystem to withstand it", she told AAP.

"Climate scientists talk about "unknown unknowns"-impacts that we haven't anticipated from existing knowledge and experience", said study co-author Scott Heron of Australia's James Cook University". This discovery fits into this category. The scientists hope that politicians would come up with solutions to tackle climate change and, subsequently, coral reefs' damage. "By focusing on especially severe marine heatwaves, we should be able to predict this direct coral death, too".

"Given that the degradation of coral reefs will result in the collapse of ecosystem services that sustain over half a billion people, we urgently need actions both globally and locally that protect and conserve these truly wonderful places".

"Across the globe coral reefs are still a source of inspiration and awe of the natural world, as well as being critically important to the communities that rely upon them".

Other reports by Click Lancashire

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