Reef health

Fact or fiction: coral bleaching 101

Do you know what is fact or fiction?

As Australia’s lead management agency for the Reef, we monitor Reef conditions very closely.

Over summer 2019-20 we issued weekly public reports about conditions on the Reef – the full series of information and video updates are below. These updates are based on forecasts, water temperature heat mapping, in-water surveys, citizen science and aerial surveys.

In addition to our regular updates, we’ve released the first Reef snapshot: summer 2019-20.  We also released statements about the mass coral bleaching that occurred on the Reef and a statement on aerial surveys, along with educational information on coral bleaching.

With summer over, we are now releasing monthly updates until the beginning of summer 2020-21 when we’ll resume weekly updates.

The Authority acknowledges the extreme impact that COVID-19 is having on tourism businesses and their communities and we are doing everything we can to support the industry in these difficult times. When it is safe to do so, we will encourage people from across Australia and around the world to see the Reef, love the Reef, and importantly protect the Reef.

Reef health - June 2020

Crown-of-thorns starfish 

Crown-of-thorns starfish outbreaks continue to impact Reef health across the Marine Park, most severely on reefs offshore in the central region and the inshore and offshore southern regions.

The crown-of-thorns starfish control program vessels continue to conduct ongoing surveillance and control in the northern, central and southern Marine Park.  Recent targeted culling effort has been focused on high value tourism sites.

Most recently, one of the control vessels surveyed five reefs in the Lizard Island region. While most of the reefs had low densities or no crown-of-thorns starfish, one reef was found to have established outbreaks.

Following this detection, the control vessel culled all sites on the reef to bring crown-of-thorns starfish numbers down to ecologically sustainable levels for coral growth and recovery.

Temperature and rainfall

Sea surface temperatures throughout the Marine Park were generally average at the end of June.

The Bureau of Meteorology is forecasting July to be drier than average for parts of Queensland’s far northern tropics.

Warmer and wetter than average conditions are predicted for much of Queensland through to September.

The Bureau’s ENSO outlook status has been shifted to La Niña WATCH. La Niña events typically bring above average spring rainfall in the Great Barrier Reef region.

Surveys conducted near Townsville

COVID-19 travel restrictions limited the amount of in-water surveys conducted this year. However with restrictions easing, surveys on reefs offshore from Townsville were conducted by the Australian Institute of Marine Science.

Preliminary observations show some levels of bleaching are still evident on most reefs in this region.

Most observations show bleaching on less than five per cent of colonies, but up to 20 per cent in some parts. Bleaching was mainly observed on the flat, crest and upper slope.

While there was evidence of some mortality due to bleaching, there wasn’t significant widespread mortality observed.

There were also low levels of crown-of-thorn starfish observed on most reefs.

Reports through Eye on the Reef

Reports of coral bleaching, disease and damage made through the Eye on the Reef program continue to observe only scattered, low-level impacts during the month of June, however numbers of reports are currently limited.

If you're visiting the Great Barrier Reef, remember to download our free Eye on the Reef app to record Reef health, animal sightings or incidents.