A volunteer team working with Citizens of the Reef has documented an unusually large coral structure on the Great Barrier Reef during surveys for the Great Reef Census. The colony was first noticed by diver Jan Pope while scanning the water surface for reef patterns offshore from Cairns, and it was later revisited and surveyed as part of the project’s effort to crowdsource images that track coral cover and identify reefs that may act as sources of larvae.

 

What Makes the Coral Find Significant

 

The coral has been identified as Pavona clavus and is described as spanning roughly 111 metres at its maximum length, covering an estimated 3,973 square metres, which is about half the area of a soccer field. The scale is what makes the finding notable, because very large coral colonies are rare and increasingly difficult to persist as bleaching events become more frequent and severe, reducing the odds that long-lived colonies can avoid repeated thermal stress.

 

How the Size Was Estimated

 

The team used photogrammetry to map the coral, stitching together photographs taken from the surface to create a three-dimensional model from which dimensions and area could be estimated. The mapping process reportedly revealed that the coral was larger than initially expected, highlighting how tools that convert imagery into measurable models can change how volunteers and scientists document large reef structures that are difficult to capture in a single frame underwater.

 

Read more: Coral Reef Microbiomes Yield Hundreds of New Microbes and a Vast Cache of Drug Like Chemistry at Risk from Warming

 

Why Scientists Want Genetic Confirmation

 

A key scientific uncertainty is whether the structure is truly a single colony originating from one polyp or a cluster of colonies that settled close together and later fused as they grew. Experts have noted that genetic testing would be needed to confirm colony status, and sampling would need to be extensive because of the coral’s size. Without that confirmation, the discovery remains highly significant as a giant Pavona formation, even if it ultimately proves to be multiple colonies rather than one continuous organism.

 

What This Says About Reef Monitoring and Resilience

 

Citizens of the Reef has positioned the Great Reef Census as a way to expand monitoring coverage by using crowd-sourced images to assess coral condition and identify areas that may serve as resilience hotspots during spawning events. The new find illustrates how citizen science can surface important reef features that might be missed by conventional survey schedules, and it also underscores why preserving rare large colonies matters, because they can represent decades to centuries of growth and may hold clues about resilience in warming seas.