Great Barrier Reef health update: Mass bleaching and COVID-19

Weekly Reef health update © GBRMPA

The Authority acknowledges the significant impact the COVID-19 virus is having on Reef related industries and communities. The Authority continue to provide updates on Reef health during this time.

Sea surface temperatures

As of 24 March 2020, sea surface temperatures (SSTs) across the Reef were mostly average and additional thermal stress is unlikely to accumulate.

Although temperatures decreased, the effects of prolonged thermal stress are still being observed across the Marine Park and we continue to receive reports of coral bleaching.

Reef-wide aerial surveys to determine the extent and severity of coral bleaching are currently under way.

The Authority has an observer on these surveys conducted by the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University.

Aerial surveys conducted last week showed most offshore reefs north of Cairns had no or low levels of bleaching. Moderate to severe bleaching was observed on inshore and mid-shelf reefs over this area.

Inshore and offshore reefs south of Cairns, particularly between Tully and Townsville, showed severe bleaching.

There was an area offshore in this northern section where reefs were more moderately bleached, including high value tourism reefs.

Inner and mid-shelf reefs surveyed between Townsville and Mackay were mostly severely bleached, but some were only moderately bleached in this central section, including high value tourism reefs.

Reefs in the Swains Pompey Reef complexes (the extreme southeast of the Marine Park) surveyed on 25 March 2020 show high variability in bleaching.

There was about one-third with no or minor bleaching, one-third with moderate bleaching and the remaining third had severe bleaching. There was no consistent north-south or inshore-offshore pattern.

Next week's outlook

Aerial surveys will be completed later this week and the analysis of the aerial survey information will occur in the weeks to follow. After this analysis, we will provide further information how the whole Reef fared this summer.

Media statement: On 26 March 2020 the Marine Park Authority issued a media statement that confirms mass coral bleaching is occurring on the Great Barrier Reef, with very widespread bleaching detected.