Peter J. Mumby

EXPERT REACTION: Is the reef resilient enough to regenerate?

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Australian and UK researchers believe that, despite the current damage to the Great Barrier Reef, there are 100 smaller reefs within it that have the correct conditions to help the ecosystem recover. They say that there is less danger in these smaller reefs of bleaching or the coral being scoffed down by crown-of-thorns starfish, and because of ocean currents, these specific reefs have the potential to provide coral larvae to almost half of the Great Barrier Reef in one year. There were, however, warnings. The scientists say that this is by no means a complete rescue of the Great Barrier Reef, and much needs to be done to protect these potential helpers locally.

Journal/conference: PLOS Biology

DOI: 10.1371/journal.pbio.2003355

Organisation/s: The University of Queensland, CSIRO, Australian Institute of Marine Science (AIMS)

Funder: The study was funded by the National Environmental Science Programme, ARC Linkage grant, Queensland Accelerate Partnership, Great Barrier Reef Foundation, Science and Industry Endowment Fund, and the National Environmental Research Program.

Media Release

From: The University of Queensland

Resilient reefs offer hope for regeneration

Just three per cent of the Great Barrier Reef’s corals may hold the key to regenerating reefs damaged after major disturbances, new research reveals.

Researchers from The University of Queensland, CSIRO, Australian Institute of Marine Science and the University of Sheffield have pinpointed 100 reefs that have the potential to supply larvae to almost half of the Great Barrier Reef’s ecosystem in one year.

UQ School of Biological Sciences and ARC Centre of Excellence in Coral Reef Studies Professor Peter Mumby said these reefs appeared to be less at risk of the damaging effects of bleaching and starfish predation.

“They are well connected to other downstream reefs by ocean currents and can provide coral larvae (fertilised eggs), which float on ocean currents, to support the recovery of other reefs,” Professor Mumby said.

The Great Barrier Reef, consisting of more than 3800 individual reefs, has suffered from unprecedented coral bleaching events over the past two years, and widespread outbreaks of coral-eating crown-of-thorns starfish.

Professor Mumby said the 100 reefs were located in consistently cool areas which rarely experienced damage from coral bleaching.

“Corals on these reefs should fare relatively well and be able to supply larvae to as many reefs as possible, without spreading the pest, crown-of-thorns starfish,” Professor Mumby said.

“Finding these 100 reefs is a little like revealing the cardiovascular system of the Great Barrier Reef.”

Professor Mumby said saving the Great Barrier Reef was possible but required serious mitigation of climate change and continued investments in water quality improvement, starfish control, and local protection.

“Our results can inform where management agencies target on-the-ground actions,” he said.

UQ School of Biological Sciences Dr Karlo Hock said the presence of these well-connected reefs meant the whole system of coral reefs possessed a level of resilience to help it bounce back from disturbances.

“Identifying only 100 reefs with this potential across the length of the entire 2300km Great Barrier Reef emphasises the need for effective local protection of critical locations, and carbon emission reductions to support this ecosystem,” Dr Hock said.

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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Dr Andrew Lenton is Principal Research Scientist at CSIRO Oceans and Atmosphere and is from the Centre for Southern Hemisphere Oceans Research, and Antarctic Climate and Ecosystems CRC

This new study highlights the biological richness and complexity of the Great Barrier Reef (GBR), which is under threat from a range of factors including climate change, water quality, coastal development and fishing.

The GBR has been significantly impacted over the last two summers, with up to 50 per cent coral mortality occurring in the Northern GBR; and while this has been very significant, corals do have a capacity to recover from such events.

This new and exciting research identifies the factors that need to be in place to maximise the capacity of corals to recover from such environmental stresses. In this study scientists bring together multiple datasets, collected over more than 3 decades, to identify those reefs which have both experienced lower environmental stresses and play a critical role in supplying fertilized larvae to other reefs.

These refugia are critical as they maintain the healthy populations and diversity required to rebuild coral populations, and have the ability to repopulate other reefs; and this paper highlights the importance of protecting and managing these refugia.

However, it also recognises that this alone is not likely to be sufficient to ensure the longer-term viability of the Great Barrier as a whole; and will need to be coupled with climate mitigation, local management and active management such as coral re-seeding.

Last updated: 28 Nov 2017 11:00am
Associate Professor John Alroy is from the Department of Biological Sciences in the Faculty of Science and Engineering at Macquarie University

This new paper is really thorough and interesting. It brings together several very different kinds of information with sophisticated modelling, and I think it makes a good case that corals will persist for a while on a fair number of reefs. But I think it's optimistic.

First off, the paper shows that almost all of the reefs most likely to survive are concentrated in the southernmost one-third of the GBR. That makes me wonder whether reefs in the far north can really be kept alive by being replenished from the south.

Second, there are so many species of animals living on the GBR – including some 1500 species of fishes – that many of them must be absent from the 'robust reefs'. Some of those species may already be gone, and others won't last long.

Third, the paper doesn't really address the fact that global warming is just going to get worse and worse over the next few decades and centuries. So, even the "robust reefs" might be wiped out in the not too distant future – unless we really get serious right now about mitigating global warming.

Last updated: 28 Nov 2017 10:58am

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    Coral showing signs of bleaching, with an entire coral colony turned white from recent stress caused by elevated sea temperatures.

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    Image 3

    Diversity of coral forms shows rich underwater life found on healthy coral reefs.

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    Attribution: Peter J. Mumby

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