The climate emergency is gathering pace as scientists continue to quantify the impacts of a heating planet and the long term viability of sustaining humanity, and the planet, as we know it. The Guardian recently reported that some of the worlds top scientists in the UN report Climate Change and Land that the ‘climate crisis is damaging the ability of the land to sustain humanity’. However, it is not just the land that is being affected by the rising temperatures in a report released today the increase in marine heatwaves is having a far more significant impact on coal reefs than previously thought.
Scientists have shown for the first time that during marine heatwaves it’s not just coral animals that are affected – their skeletons also start to decay within weeks. his means that the 3D coral framework which provides home to many other animals on the reef is also at risk.
The team of researchers from UNSW Sydney, The University of Newcastle, The University of Technology Sydney, James Cook University and The National Oceanic and Atmospheric Administration (NOAA) have shown that severe marine heatwaves not only trigger bleaching events, but in fact can lead to heat-induced mortality of the coral animal itself. They suggest that severe heatwave-induced mortality events should therefore be considered a distinct biological phenomenon, with more direct damage different from coral bleaching.
‘Until now, we have described coral bleaching as an event where the symbiotic relationship between coral and its microbes breaks down and corals lose their main source of nutrition, and the coral can die if the symbiosis is not restored,’ author Associate Professor Tracy Ainsworth from UNSW says.
‘But what we are now seeing is that severe marine heatwave events can have a far more severe impact than coral bleaching: 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.
‘We find that the skeleton is immediately overgrown by rapid growth of algae and bacteria,’ says Associate Professor Bill Leggat of the University of Newcastle, a co-author on the paper.
As marine heatwaves increase the team predict that rapid reef decay will become more frequent.
Dr Scott Heron from James Cook University says this rapid dissolving of coral skeletons following severe heatwaves hasn’t been known to date.
‘Climate scientists talk about “unknown unknowns” – impacts that we haven’t anticipated from existing knowledge and experience. 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,’ he says.
Tell your politicians
Associate Professor Ainsworth says that the team hopes that this research will motivate the public to tell decision makers how important coral reefs are to them, and voice the immediate need to preserve coral reefs now.
‘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. 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.’
Find the contact details for Senators and Members at the Parliament of Australia.
Click for the contact details for members of state parliament.