Marine Heatwaves Seen as Greatest Threat to Coral Reefs

Evidence of coral bleaching.

(CN) – Heatwaves and rising temperatures represent a much greater threat to coral reefs than was previously believed, according to a study published Thursday.

The study, published in the journal Current Biology, examined data from state-of-the-art CT scanning of coral skeletons to better understand how coral reefs are responding to changing climate factors. What researchers discovered was that when heatwaves occur in marine environments, the actual skeletal structure of coral reefs began to breakdown and die-off in the increased heat.

Previous research suggested that the greatest threat to coral reefs experiencing increased water temperatures was coral bleaching, a process that causes coral to release dangerous amounts of algae and turn white.

This new research, however, suggests that as temperatures continue to rise, coral bleaching is being eclipsed by a far more severe threat: that of coral reefs dying and decomposing.

Coral skeleton. (Tracy Ainsworth / UNSW)

Researchers, led by Tracy Ainsworth, professor in the School of Biological, Earth and Environmental Sciences at the University of New South Wales, Sydney, discovered that this die-off is caused by increased levels of bacteria that infect coral skeletons when marine heatwaves increase in frequency and intensity. The bacteria force the coral to degrade significantly, ultimately leading to death and skeletal decay.

The study notes that should coral reefs begin to experience extinction events caused by the increased heat, surrounding marine environments will experience harsh consequences. Numerous sea creatures depend on coral reefs for safety and survival, and should coral reefs experience die-off, such creatures will find their ability to thrive severely diminished. The study suggests this could lead to the collapse of several ecosystem functions, and millions of people and countless organisms would be negatively affected.

The researchers stress the importance of continual research into coral reefs and their sensibility to climate change factors, and that scientists must continue to use available models to predict and respond to any future coral reef extinction events.

Ainsworth did not immediately respond to a request for comment.


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