Reef health

Each summer, we assess the health of reefs in the Great Barrier Reef Marine Park, as this part of the year poses a greater risk of extreme weather, particularly heat waves, cyclones and flooding. Stressful conditions can lead to coral disease outbreaks, while poor water quality may make coral more susceptible to bleaching and lead to greater numbers of coral-eating crown-of-thorns starfish.

We use the best available scientific knowledge contributed by a wide range of research institutions, government agencies, and universities to manage the Great Barrier Reef and ensure it remains healthy for future generations.

It’s important we have accurate, real-time information on Reef conditions. Any visitors to the Reef can report observations of coral bleaching, disease, predation or damage through the Eye on the Reef program. Everyone — regardless of where they live — can help look after the environment by reducing their carbon footprint, for example by recycling, avoiding excess packaging and plastic bag use, reducing energy use by choosing energy-efficient appliances, and using environmentally friendly cleaning products and fertilisers.

When visiting the Great Barrier Reef Marine Park comply with zoning rules, don’t anchor on coral, use public moorings, reduce debris, keep plant-eating fish on the Reef, report illegal fishing, and supply information on Reef health via our Eye on the Reef app.

Update 3: End of season wrap up 2017-2018

Overview of environmental conditions

The start of the summer period (December 2017 to February 2018) was marked by the commencement of a weak La Niña event. The event persisted throughout summer and concluded by early autumn 2018, when El-Niño Southern Oscillation indicators returned to neutral levels. La Niña events are typically associated with above average rainfall conditions in eastern Queensland, however this particular weak, short-lived event did not have a significant influence on summer conditions.

Summer 2017/2018 was the second warmest on record in terms of mean temperatures for both Australia and the state of Queensland. Rainfall was average nationally, however for Queensland this summer was drier than average despite the above average rainfalls in some regions during February.

While mean maximum temperatures were below average for Queensland in March 2018, much of the state experienced warmer than average nights.  March was also characterised by above average rainfall in the north and west of the State, leading to the wettest March in Queensland since 2012.  Numerous flood events affected much of the northern tropics during this period. Australian Institute of Marine Science (AIMS) hydrodynamic models indicate that the heavy rainfall and resultant flooding resulted in decreased salinity on inshore and mid-shelf regions of the far northern, northern and central areas of the Great Barrier Reef Marine Park.

April brought further warm conditions - the first half of April 2018 was abnormally warm almost nation-wide, with the Bureau of Meteorology releasing a special climate statement to summarise the findings.  In Queensland it was the fourth-warmest April on record in terms of mean temperatures, and conditions were considerably dry across most of the state.

Throughout summer and into March and April, sea surface temperatures throughout the Marine Park generally fluctuated between average and above average. Some areas, particularly the inshore regions, experienced periods of significantly above average temperatures. Thermal stress accrued throughout the entire Marine Park, particularly in the far northern and southern management regions, as well as the inshore regions of the central management area.

In April, tropical cyclone Iris, the only cyclone to affect the Great Barrier Reef this season, briefly tracked parallel to, but well offshore of the Queensland coast as a Category 1 and then Category 2 cyclone before downgrading to a tropical low.  At its peak, Iris brought rain and damaging wind gales to the central and southern Great Barrier Reef, in particular the Mackay/Whitsundays region.

Our table of observations and forecasts provides more detailed information.

Reef health monitoring is ramped up over this time to keep an eye on the marine environment.

Overview of coral reef health reports

Prior to summer 2017/2018, multiple significant impacts affected the Great Barrier Reef over the years 2016 and 2017, including severe coral bleaching, outbreaks of coral disease and crown-of-thorns starfish, and a severe tropical cyclone and subsequent flood plumes. A separate summary of these past reef health impacts is available.

Reports from the Eye on the Reef network indicate that, following summer 2017/2018, there are currently minor levels of coral bleaching, disease and damage in the Marine Park. Severe active outbreaks of the coral-eating crown-of-thorns starfish continue in the northern and central management areas, as well as in the southern Swain Reefs.

The full impacts of the major flooding on the tropical northern coast, and cyclone Iris on the central and southern management areas, are yet to be determined.

The Marine Monitoring Program flood response team was mobilized following the flood events to sample the resultant flood plumes. In addition, modelling is being undertaken by AIMS to determine the area potentially impacted by damaging waves associated with tropical cyclone Iris.

Any long-term flood or cyclone-related impacts on coral reefs will be determined by the Reef 2050 Marine Monitoring Program and AIMS Long-Term Monitoring Program surveys.

Our crown-of-thorns starfish control program has continued scheduled culling on selected reefs in the Cairns–Cooktown and Townsville–Whitsundays management areas to help protect corals.

Since the control program began in 2012, more than 600,000 starfish have been culled from reefs of high tourism and ecological value in the Marine Park. The control program’s capacity to protect coral will be expanded with more vessels joining the fleet in 2018.

Want to help us keep an eye on the Great Barrier Reef?

Find out more about how you can get involved in our monitoring programs.

Subscribe to our e-newsletter for further updates on Reef health and management.

Timeline and actions

Key timeline and activities for understanding how coral bleaching and severe tropical cyclone Debbie impacted on the Reef.

Read more on Timeline and actions

Final report: 2016 coral bleaching

Final report by the Great Barrier Reef Marine Park Authority on the 2016 coral bleaching event.

Read more on Final report: 2016 coral bleaching

Coral bleaching news releases

News releases by the Great Barrier Reef Marine Park Authority on coral bleaching.

Read more on Coral bleaching news releases

Current conditions on the Reef

Summary and detailed information on sea surface temperature, tropical cyclones, rainfall levels and flood plumes to date.

Read more on Current conditions on the Reef

2016 coral bleaching event

Mass coral bleaching on the Great Barrier Reef in 2016 was triggered by record-breaking sea surface temperatures.

Read more on 2016 coral bleaching event

Frequently asked questions

Find answers to your questions about bleaching on the Reef.

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Coral bleaching resources

Coral bleaching resources: Image gallery, bleaching infographic, informative video and map of observed bleaching.

Read more on Coral bleaching resources

Responsible reef practices – Spearfishing

Fishers and spearfishers should consider leaving plant-eating fish to help control seaweed and enable coral larvae to settle and create new colonies.

Read more on Responsible reef practices – Spearfishing

Student and teacher resources

Educational materials, including teaching units and a poster series, for primary and secondary school students.

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Eye on the Reef program

Eye on the Reef is a monitoring program that enables anyone who visits the Reef to contribute to its long-term protection.

Read more on Eye on the Reef program

Using the Eye on the Reef app

Download the free Eye on the Reef smart phone app from iTunes/Google play app store or you can use the desktop app to report your Reef sightings.

Read more on Using the Eye on the Reef app

Coral Bleaching Response Plan

The Coral Bleaching Response Plan was developed to meet the challenge of responding to coral bleaching events.

Read more on Coral Bleaching Response Plan

Sea surface temperatures

Australia’s Bureau of Meteorology provides information on sea surface temperatures for monitoring coral bleaching.

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ReefTemp Next Generation is a set of high resolution mapping products that provide information on coral bleaching risk for the Great Barrier Reef region.

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