The Great Barrier Reef has seen an increase in coral cover, but risks still remain. 

Coral cover has increased across all three Great Barrier Reef regions, reaching record highs in two areas, according to the latest report from the Australian Institute of Marine Science (AIMS). 

However, this promising news is tempered by concerns over the lasting impact of recent environmental disturbances, including a severe mass bleaching event and tropical cyclones.

AIMS has revealed that underwater surveys conducted between August 2023 and June 2024 recorded significant gains in coral cover. 

The Northern region (north of Cooktown) saw an increase from 35.8 per cent to 39.5 per cent, while the Central region (Cooktown to Proserpine) rose from 30.7 per cent to 34 per cent. 

The Southern region (south of Proserpine) experienced a jump from 34 per cent to 39.1 per cent. 

These figures indicate the highest levels of coral cover recorded in the Northern and Central regions since AIMS began monitoring 38 years ago.

Dr Mike Emslie, leader of AIMS’ Long-Term Monitoring Program (LTMP), described the increases as a positive sign, but emphasised that these results do not account for the full impact of the 2024 mass bleaching event and subsequent cyclones. 

"We saw evidence of early onset mortality, particularly in the Southern region, but the full picture of mortality was not yet apparent during this year’s surveys," he said. 

He noted that bleached corals, though stressed, were still alive when surveyed, meaning that their true condition would only become clear in subsequent assessments.

The timing of the surveys is critical, as most were completed before the onset of significant environmental disturbances. 

The Central region’s surveys were finished before the passage of Tropical Cyclone Jasper in December 2023. 

Additionally, the team surveyed reefs off Townsville in late January after Tropical Cyclone Kirrily, documenting coral damage and reductions in cover of 6 per cent to 10 per cent at several sites.

Still, “we are only one large-scale disturbance event away from a reversal of the recent recovery,” said Dr David Wachenfeld, AIMS Research Program Director.

Aerial surveys conducted by AIMS and the Great Barrier Reef Marine Park Authority in early 2024 found bleached corals on 73 per cent of the reefs surveyed, raising concerns about the long-term survival of these ecosystems. 

Dr Wachenfeld pointed out that almost half of the approximately 3,000 reefs in the marine park experienced more heat stress than ever before, and the full extent of coral mortality remains unknown.

The next LTMP survey season will begin in September, focusing on the aftermath of the 2024 bleaching event and the cyclones, with a comprehensive assessment expected by mid-2025.

More information is available here.