Reef health

MAP1_GBRMPA Aerial Survey GBR Reef Avg Bleaching Scores All Categories MAR2022 As Australia’s lead management agency for the Reef, we monitor Reef conditions very closely throughout the year. From May to November each year, we issue regular Reef health reports. Over summer, we issue weekly public reports on the conditions of the Reef.

These updates are based on forecasts, water temperature heat mapping, in-water surveys, citizen science and aerial surveys. The current updates are available below and past Reef health updates are also available.

Reef Snapshot: summer 2021-22

The Reef snapshot: summer 2021-22 provides a concise, easy to understand summary of how the Reef has fared over the past summer, what this means for coral and the actions being taken to help coral health.

Map 1: 2022 Aerial Survey observations of reef community coral bleaching throughout the Great Barrier Reef after the final heat wave from 12-23 March 2022. A total of 719 reefs were surveyed by a combination of helicopter and fixed-wing aircraft. Categories are described in the AIMS Standard Operating Procedure.

Findings of the 2022 aerial surveys

The Great Barrier Reef’s waters warmed early in December 2021, exceeding historical summer maximums that typically occur in the hottest summer months.  Ocean temperatures continued to accumulate heat throughout the summer until early April 2022, with three distinct heat waves increasing thermal stress throughout the Central and Northern Great Barrier Reef (GBR).

This prolonged heat exposure led to a mass bleaching of coral across the Great Barrier Reef; the fourth to occur in seven years. Unusually, this was the first mass bleaching event to occur under La Niña conditions.

Increased reports of coral bleaching prompted Reef-wide aerial surveys in the second half of March 2022 to assess the extent of coral bleaching. Aerial surveys were conducted by trained observers from the Great Barrier Reef Marine Park Authority and the Australian Institute of Marine Science.

  • A total of 719 reefs were surveyed from the air between the Torres Strait and the Capricorn Bunker Group in the Great Barrier Reef Marine Park.
  • Of these, 654 reefs (91 per cent) exhibited some bleaching. Coral bleaching observed from the air was largely consistent with the spatial distribution of heat stress accumulation, with a greater proportion of coral cover bleached on reefs that were exposed to the highest accumulated heat stress this summer.
  • The 2022 Aerial Survey Map illustrates the variation in bleaching observed across the Reef in the latter half of March.

Results by region

Northern region - includes coral reefs from the tip of Cape York down to Lizard Island and Cape Tribulation:

The pattern of shallow-water coral community bleaching as seen from the air varied from minor (1-10 per cent coral cover bleached) to severe (61-90 per cent bleached), with severity generally increasing from the northern tip of Cape York down towards Princess Charlotte Bay. Coral cover and the community composition were important factors influencing community bleaching severity through this region, with many reefs dominated by temperature tolerant massive Porites, which did show signs of bleaching at the more impacted sites in southern Princess Charlotte Bay.

Central region - includes reefs from Cape Tribulation, south to the Whitsundays.

The onset of coral bleaching around the Townsville region was captured during a preliminary aerial survey of 43 reefs in early February 2022, after a prolonged period of thermal stress. These preliminary surveys found 87 per cent of reefs exhibited minor to moderate bleaching (11-30 per cent bleached) (see 4 February 2022 Townsville Aerial Survey Map2).

Reef-wide surveys in the second half of March found the pattern of reef community bleaching, as seen from the air, increased in severity compared to early February, following additional heat stress. Community bleaching ranged from major (31-60 per cent bleached) to extreme (>90 per cent bleached) on the shallow parts of reefs from Cooktown to the Whitsundays.

The most severe bleaching occurred on both inshore and offshore reefs throughout this region. Inshore, mid and outer-shelf reefs between Lizard Island and Townsville had a higher abundance of tabular Acropora corals on the shallow reef flats and crests, compared to the Northern and Southern regions.

Southern region - includes reefs from the Pompey Reef area down to the Capricorn-Bunker area and out to Swain Reefs.

Within the southern region, bleaching was highly variable, reflecting the boundary of lower heat stress exposure. Some shallow-water coral communities in the southernmost parts of the Reef exhibited no bleaching (around the Capricorn Bunker Group), with others further north exhibiting major to severe community bleaching offshore Mackay.