A mother-and-daughter duo of citizen scientists has uncovered the largest known coral colony on Australia's Great Barrier Reef, measuring 111 meters across and covering nearly 4,000 square meters. The J-shaped formation of Pavona clavus was found during a dive as part of the Great Reef Census initiative. Advanced 3D modeling confirmed its size, highlighting the role of community involvement in marine conservation.
Sophie Kalkowski-Pope, marine operations coordinator at Citizens of the Reef, and her mother Jan Pope, an experienced diver and underwater photographer, spotted the massive coral colony during a recent dive on the Great Barrier Reef. The discovery occurred late last year while participating in the Great Reef Census, a conservation project that engages citizen scientists to collect reef imagery and data.
The colony, described as a J-shaped formation of Pavona clavus, spans 111 meters—roughly the length of a football field—and covers about 3,973 to 4,000 square meters. Jan Pope recognized its scale from a previous dive and returned with Sophie to document it properly. 'The moment we entered the water, I immediately understood the significance,' Sophie said. 'It took a three-minute video just to swim across the colony.' Jan added, 'When I got in the water, I’d never seen coral growing like this before. It looked like a meadow of coral. It just went on and on.'
To verify the size, the duo combined manual underwater measurements with high-resolution aerial imagery, creating a detailed 3D model. This was developed with assistance from the Centre for Robotics at Queensland University of Technology. 'Spatial modelling like this is vital,' said Serena Mou, a research engineer there. 'It lets us return months or years later and make exact comparisons to see how the coral evolves.'
Preliminary analysis suggests strong tidal currents and low exposure to cyclone waves may have enabled the colony's growth. The exact location is withheld to prevent damage. Experts note its significance amid threats like mass bleaching events, which have affected over 80% of global reefs since 2023 due to record ocean temperatures. Michael Sweet, professor of molecular ecology at the University of Derby, called it 'bigger than any coral I have personally seen' and emphasized citizen scientists' role in monitoring.
Andy Ridley, CEO of Citizens of the Reef, praised the 'people power' behind such initiatives. Pete Mumby of the University of Queensland’s Marine Spatial Ecology Lab said the census helps identify key areas for reef recovery. Despite the find, experts warn it does not indicate overall reef recovery from climate pressures.
