Flood run off January 4, 2011 NASA image courtesy Norman Kuring, Ocean Color Web. Caption by Michon Scott.

Dirty river run-off the biggest barrier to Great Barrier Reef recovery

Embargoed until: Publicly released:
Corals on the Great Barrier Reef that are exposed to poor quality water from river run-off, like the plumes seen following the recent Townsville floods, recover more slowly from disturbances and are more susceptible to coral disease, according to Australian research. The study found that while reefs exposed to poor water quality are more resistant to coral bleaching, this is cancelled out by them being slower to recover from disturbances, so that the overall impact is a negative one. The researchers found that improving water quality by between 6 and 17 per cent may buffer the predicted increases in coral bleaching at some inshore locations.

Journal/conference: Nature Ecology and Evolution

Organisation/s: Australian Institute of Marine Science (AIMS), The University of Adelaide, ARC Centre of Excellence for Coral Reef Studies, Queensland University of Technology (QUT), ,Dalhousie University, Canada, ARC Centre of Excellence for Mathematical and Statistical Frontiers (ACEMS)

Funder: Australian and New Zealand newspapers have permission from the journal to run this story in print on the day the embargo lifts, with the strict proviso that nothing can appear online until after the embargo lifts.

Media Release

From: Springer Nature

[1] Water quality boosts reef recovery

Coral reefs exposed to poor water quality recover slowly from disturbances and are more susceptible to coral disease, reports a paper published online this week in Nature Ecology & Evolution.  The study finds that improving local water quality may help some reefs better withstand the bleaching impacts of climate change, but these efforts are insufficient to save the most iconic reefs.

Climate change and other pressures are already damaging broad sections of the Great Barrier Reef. The future resilience of this reef will be determined by its ability to resist disturbances and recover from coral loss.

Aaron MacNeil and colleagues used data on coral cover collected from 46 locations in the Great Barrier Reef between 1995–2017 to assess how damage inflicted by tropical cyclones, disease outbreaks and coral bleaching have affected the reef. They also examined how well the reef recovered from various types of damage.

The authors found that poor water quality, resulting from river run-off, was the biggest impediment to coral recovery. They found that corals in areas with poor water quality were in fact somewhat more resistant to coral bleaching, due to the low level of light penetrating the turbid water.  However, these corals recovered from bleaching more slowly and were more susceptible to disease outbreaks.

The authors suggest that a 6–17% improvement in water quality may buffer the predicted increases in coral bleaching at some inshore locations. This level of improvement is within the scope of local government improvement plans, although the targets are unlikely to be met. However, the authors caution that improvements in water quality alone will not protect the heat-sensitive corals typical of outer-shelf reefs.


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