Spawning on the Great Barrier Reef

In an extraordinary breakthrough for global reef restoration, MARRS Reef Stars have been directly witnessed spawning on the Great Barrier Reef (GBR) for the first time. The historic moment was observed by the Reef Co-operative team and Mars Sustainable Solutions', Freda Nicholson, at the Reef Magic pontoon during the 2025 mass coral spawning event—marking a major step forward in demonstrating that active reef restoration can restore functioning, reproducing coral ecosystems to degraded sites. 

The sighting occurred at Moore Reef, where the very first MARRS Reef Stars were installed on the GBR between 2020 and 2022. While scientists had previously detected evidence of reproduction, this is the first time spawning has been directly witnessed as it happened. 

On the night, the team observed extensive spawning from several species of branching Acroporid corals attached to the Reef Stars. This year’s spawning is a split event, with another expected during the first week of December, when table and digitate corals are predicted to release their gametes. 

This milestone was observed at the end of a busy Reef Recovery Day, where visitors joined scientists and Traditional Owners to help build Reef Stars, contribute to Great Reef Census activities, and learn firsthand about Sea Country stewardship. The direct observation of Reef Stars spawning marks a powerful milestone for the Reef Co-operative, which this year celebrates five years of collaborative work on Yirrganydji and Gunggandji sea Country. Since 2020, the partnership—uniting Traditional Owners, marine scientists, tourism operators, and conservation organisations—has installed more than 900 MARRS Reef Stars, trained 24 Reef Intervention Trainees, and contributed 173,000 Great Reef Census images to guide reef protection and identify reefs that are in need of a helping hand 

At the heart of the action was the Mars Assisted Reef Restoration System. Coral fragments were attached to hexagonal, sand-coated steel Reef Stars, which were then installed onto unstable coral rubble created by storms and other disturbances. The frames stabilise the rubble and provide a foundation for new coral growth. Over time, these networks transform degraded areas into vibrant, hard-coral-dominated habitats—jumpstarting natural recovery processes that typically unfold over decades. 

Observing reproductively mature corals on previously installed Reef Stars confirms that restoration activities are successfully reinstating key ecological functions rather than solely restoring habitat structure. These spawning corals are now contributing larvae that can drift, settle, and seed neighbouring reefs, demonstrating that strategic intervention can meaningfully enhance resilience across the wider Great Barrier Reef.