Australia’s Great Barrier Reef is a true natural wonder: a unique and diverse underwater seascape the size of a small country.

However, cycles of disturbance and recovery threaten to turn its colourful coral gardens into algal-dominated seascapes – then back again. And these cycles are becoming more volatile as our world warms.

At the Australian Institute of Marine Science, we’ve been documenting these changes for the past four decades through our Long-Term Monitoring Program. This is one of the longest records of continuous coral reef data in the world.

Concerningly, we’ve watched the health of the Great Barrier Reef begin to fluctuate dramatically over the past 15 years. The 2024 mass coral bleaching – where a record-breaking marine heatwave bleached coral reefs from the Caribbean to the Indian and Pacific Oceans – was particularly destructive. It caused the largest single-year decline in coral ever measured in two regions.

However, our latest report reveals some promising signs of recovery.

In 2025, the Great Barrier Reef endured its sixth coral bleaching since 2016 – one of only two back-to-back bleachings in the reef’s history.

However, our latest survey data shows the 2025 bleaching was smaller and less severe than in 2024.........

© The Conversation