In a finding that could significantly improve coral restoration efforts worldwide, Queensland Univerity of Technology (QUT) researchers have uncovered critical biological processes that allow corals to attach to a reef.
Led by Dr. Brett Lewis from the QUT School of Earth and Atmospheric Sciences, the study (published in Royal Society Open Science), investigated how coral fragments from three species, Montipora mollis, Pocillopora verrucosa and Acropora millepora, develop self-sustaining attachment to reef surfaces.
“Coral reefs are declining globally, and their recovery often depends on broken fragments reattaching and growing, but that process isn’t as simple as it sounds,” Dr. Lewis said. “Even after decades of coral research, we still don’t fully understand how fragments attach or how to make restoration efforts more effective.”
The QUT research team also included Professor Peter Prentis and Associate Professor Luke Nothdurft, along with Dr. Crystal Cooper from University of Western Australia and Professor David Suggett from UTS.
Using advanced microscopy, researchers have identified a three-step process in coral fragments attaching to the surface of a reef.
“First, they respond to contact by tissue through an immune response and transitioning their tissues—almost like flipping yourself inside out,” Dr. Lewis said. “Next, they anchor themselves with this new soft tissue. Finally, they build a skeleton—normally inside the coral—onto the reef using a specialized appendage which can creep over the reef substrate using its cell to grow the skeleton and sterilize any pathogens or other organisms that get in its path.”
Dr. Lewis said the nature of the appendage played a critical role in coral restoration, as it determined how well and how quickly coral fragments could become self-sustaining.
“Our findings reveal that while the overall attachment process is conserved across coral species, there are distinct biological differences that influence how quickly and effectively corals secure themselves to the reef,” he said.
One noticeable difference was the coral’s attachment appendage and its efficiency growing onto the reef in killing pathogens or even other organisms that get in its way, with more complex appendages leading to faster growth and stronger skeletons in some corals compared to others.
With Montipora mollis, the appendage was larger and more complex, leading to faster and stronger attachment. However, with the Pocillopora verrucosa, the appendage was thinner and slower to develop, which could explain the weaker initial attachment.
“We also found that tiny thread-like structures called mesenterial filaments play a bigger role and are more diverse than we previously thought,” Dr. Lewis said. “Part of the coral’s internal anatomy, they help coral fragments prepare to attach by digesting their own tissues that are no longer needed—eating themselves. This suggests they’re important not just for attachment, but also for helping corals recover and stay resilient when they have damaged tissues or are going through stress or change.”
Dr. Lewis said the work would help coral restoration take another step beyond a one-size-fits-all approach.
“By understanding the attachment processes and their underlying cellular and skeletal differences between species, we can better target corals for restoration and predict which corals will thrive in specific environments and grow fastest, tailoring restoration strategies accordingly,” he said.
[image: Coral polyp cross-section. Credit: Dr. Brett Lewis]
