Coral restoration is a dynamic, evolving field with a wide array of techniques and methodologies. It is part of a broad toolkit of conservation and management measures now being used across the tropics to help ensure the survival of coral reefs globally. Restoring corals is not just about protecting biodiversity; they are essential on multiple levels, from coastal protection, supporting medical discoveries, providing food, sustaining fisheries and tourism to support economies and directly support the income for 500 million people. Over this two part blog series we will be diving into coral restoration methods, used both on our projects and emerging techniques that give us hope for the future of our reefs.
Coral Reefs in a Changing Planet
Coral reefs represent less than 0,2% of the oceans’ surface. yet they help sustain 25% of all marine species worldwide. Their presence is critical for the stability of the oceans. Unfortunately, they’re under severe threat from climate change, which is driving ocean heating, acidification, rising sea levels, and more frequent, intense storms. On top of this, pollution and other human activities continue to accelerate their decline.
These changes are happening far too fast for corals to naturally adapt. The planet’s 10 warmest years since 1850 have all occurred in the past decade, and in 2024, global temperatures have exceeded the 1.5°C threshold for the first time (1.55°C ± 0.13°C, WMO, 2025).
Since 1980, 50% of global coral reefs have been lost. And their significant decline is more important than ever: projections indicate coral cover could decline by 70% – 90% by 2050 depending on emissions scenarios. We are witnessing the potential extinction of an entire global ecosystem, but there is still hope.
As the scale of coral loss accelerates, the conservation and restoration fields are racing to innovate and adapt, working to meet this challenge with urgency. But without wide-scale intervention, coral populations will not recover on their own.
Our Techniques: Coral Gardening
From nursery to the transplanted colony
Coral gardening, or coral propagation, is a widely used method that takes advantage of corals’ ability to asexually reproduce to restore damaged reefs. Before corals are returned to their final home, they are grown in underwater nurseries for a few months. This “nursery stage” helps them grow stronger and better prepared for life on the reef.
Why is this important? Well, moving coral to a new location can be stressful. By allowing them grow bigger and healthier in the nursery, we give them a much better shot at surviving and thriving.
How we do it
Once the corals are the appropriate size, there are a number of methods used to secure them onto the reef substrate. We use underwater cement and epoxy, these are ideal for a strong, lasting bond, easy to prepare and cost-effective for mass planting. Additionally Coral Clips® can be a less invasive and speedy method to outplant branching corals and keeps corals in place while they settle in.
Where do they grow?
We’ve got a few options depending on the restoration site and goals:
• Natural rocks and degraded reef substrate: these make up the majority of our restoration sites
• Reef Balls: specially designed concrete structures that mimic a coral reef
• Frames: these interlocking metal frames frames are used to secure rubble beds
• Other Artificial Structures: these can look like anything from a big frame to a Manta sculpture!
Our Techniques: Artificial Reef Substrates
For corals, the choice of substrate is crucial for their survival and long-term growth. Corals require a stable, hard surface to attach to. Sediment can bury them, leading to suffocation, and rubble beds lack the structural integrity needed for corals to bond with the rock and form the reef.
As we lose corals, the structure of the reef that they build also degrades, coral skeletons erode into rubble beds. Once this happens the reef ecosystem not only loses its foundation species (corals) but the complex structure of the habitat they create, and which sustains thousands of creatures.
To mimic the natural foundation that takes thousands of years to form, artificial substrates like Reef Balls and coral frames provide a stable and durable base for coral attachment. These structures not only support coral growth but also help rebuild reef habitats by creating surfaces for marine life to colonize, ultimately a shelter for many reef species.
Our Techniques: BioRock Reefs
Also called Mineral Accretion Technology, the technique was developed by architect Wolf Hilbertz and marine biologist Tom Goreau. They found that by running a small electrical current through seawater, a hard shell of calcium carbonate would form on the cathode. Corals, which rely on calcium carbonate for growth, benefit from this additional supply, allowing them to redirect energy toward growth. Our Biorock structures, powered by solar panels, show great potential, particularly in degraded environments where natural recovery is slow.
Our Techniques: Micro-fragmentation
Micro-fragmentation is a technique where corals are broken into tiny fragments to accelerate their growth due to an increased surface area. These fragments are then fused back together to form larger colonies. This technique, initially developed by Dr David Vaughan and the Mote Marine Lab, can increase growth rates of corals by 40%.
For this process, we need exact cutting tools, that will not only cut to the sturdiest massive colony, but will also accurately cut between the polyps. By doing a clean cut of micro fragments (<10mm width) and prevent the blade and coral from overheating, the bandsaw will boost the growth of the coral and the ability to restore ancient coral colonies quickly.
That is a strong tool when associated to land nurseries, but can also but used with in-water coral nurseries. This technique not only has the ability to boost growth rates but also allows us a effective way to grow massive coral species, increasing the genetic diversity of corals in our projects.
What’s next?
Coral gardening, artificial reef structures, and microfragmentation are key techniques in the fight to restore our planet’s coral reefs. These methods show that, with ingenuity and dedication, we can help corals survive and even thrive at local scales, despite increasing environmental pressures. However, it’s essential to recognize that these methods are mitigation strategies—tools to buy time for reefs while the root causes of their decline, such as climate change and pollution, must be addressed globally.
Ultimately, coral restoration is not about returning to an idealized past but creating a more adaptive and resilient future for our reefs. While the journey is challenging, the progress made thus far is a testament to what can be achieved when passion meets perseverance!
Look out for our second blog in this series soon to journey into the emerging innovations in coral restoration…
Thanks to Marine Biologist and Educator Cyril, and our Head of Science Georgina for this blog!
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