<the Editor says: Did you know? Healthy coral reefs can absorb up to 97% of wave energy, shielding coastal areas from the impact of storms, waves, and flooding. But because coral grows extremely slowly, some scientists have begun training AI to assist with coral restoration efforts, helping coral grow and recover more quickly. Follow the Editor and let's take a look! Full article reprinted from the Low-Carbon Life Blog, co-produced with the Environmental Information Center; author: Chen Mei-Ling.>
The underwater world is filled with tree-like clusters of coral. These animals, which grow mainly in tropical waters, are made up of many polyps (Polyps). Polyps absorb calcium carbonate from seawater to form hard outer shells, and over time these accumulate into the coral reefs we know today. Although coral reefs cover only about 0.2% of the ocean floor, they provide habitat for more than a quarter of all marine species.
Although coral reefs cover only about 0.2% of the ocean floor, they provide habitat for more than a quarter of all marine species. Photo: Hiroko Yoshii／Unsplash
Coral is extremely sensitive to changes in ocean temperature and pH. Rising ocean temperatures and increasing acidity can both cause coral to become sick or die. According to a report by the Global Coral Reef Monitoring Network (GCRMN), a 1.5°C rise in seawater temperature could wipe out 70% to 90% of the world's coral. Some scientists have even estimated that, under the threat of warming, coral could disappear entirely by 2070.
Coral grows very slowly. The conventional approach to coral restoration typically involves cultivating small coral fragments in land-based nurseries before transplanting them onto damaged reefs. This method, however, is both costly and time-consuming, and can only prioritise the most critically endangered reefs. To combat the effects of warming on coral, researchers around the world have developed a range of new technologies to support coral restoration and conservation efforts.
Robots Step Up as Coral Restoration Champions
About 60 kilometres off the coast of Western Australia, in the shallow waters of the Abrolhos Islands — often called Western Australia's Great Barrier Reef — scientist Taryn Foster and her team are training artificial intelligence (AI) to assist with coral restoration work.
Foster's team designed a flat, concrete disc fitted with grooves and a handle to serve as a coral growing base. Scientists train robots to produce plugs sized to match coral fragments, automating the repetitive labour of manual restoration, before deploying the bases in batches on the seafloor.
The results so far have been encouraging. Foster says, "We've deployed several models with different reef structures and tested them on four different coral species — they're all growing well."
Scientist Taryn Foster deploys coral growing bases in batches on the seafloor. Photo: AUTODESK press release
Foster's startup, Coral Maker, has gone a step further by partnering with software giant Autodesk to train AI and collaborative robots (cobots), enabling robots and humans to work together to accelerate coral restoration.
The robots handle the repetitive pick-and-place tasks involved in the restoration process. Robotic arms produce plugs matched to the size of each coral fragment and attach them to the growing bases, while researchers use imaging to determine how the robot should grasp each piece. Even fragments of the same coral species can vary greatly in shape, so the robots require extensive training to recognise coral shapes and produce correctly fitted bases.
Coral Maker's next step is to move the proof-of-concept (PoC) phase out of the lab within a year and a half. Returning coral to the seafloor, however, is no small feat — doing so without damaging the coral or the equipment remains a significant challenge.
Training AI to Listen — Giving Coral a Health Check
Beyond using robots to assist with restoration, AI can also help monitor the health of coral reefs. In recent years, soundscape research on coral reefs has attracted considerable attention, yet coral soundscapes are highly complex and experts often struggle to extract health information from recorded audio.
In 2022, a study published in Ecological Indicators marked a new breakthrough. Scientists from the University of Exeter (UK), working on the Mars Coral Reef Restoration Project in Indonesian waters, collected and recorded sounds from both healthy and degraded coral reefs. They then trained an AI to distinguish between the two, achieving an accuracy rate of 92% — a result that holds great promise for tracking the progress of coral restoration projects.
Ben Williams, a doctoral candidate at University College London's Centre for Biodiversity and Environment Research, noted that traditional visual and acoustic coral surveys require large amounts of intensive labour. Deploying hydrophones in the water — especially in remote locations — is also far easier and more cost-effective than bringing in teams of dive experts to conduct large-scale underwater surveys.
The organisms and fish living within coral reefs can produce a wide variety of sounds whose meaning is not always clear. Using machine-learning algorithms, the research team used computers to filter out acoustic patterns that the human ear cannot detect. Through AI, it becomes possible to assess the overall health of a reef — faster and more accurately than ever before.
Bleaching and Freezing: Innovative Techniques to Help Protect Coral
Another new technology for protecting coral reefs comes from a research team at Texas A&M University. Called isochoric vitrification, the technique involves selecting coral fragments and cryogenically preserving them using a combination of strategic bleaching and liquid nitrogen, storing coral at an ultra-low temperature of −196°C without causing freeze damage.
Scientists are testing isochoric vitrification technology to assist coral conservation efforts. Photo: Cryopreservation and revival of Hawaiian stony corals using isochoric vitrification paper／Nature Communications
Coral reproduces only during a brief window of just a few days each year. Scientists have previously used cryopreservation to collect reproductive cells during spawning events, but in addition to having to time the collection precisely, reaching coral in hard-to-access locations has always been another challenge. The innovative technique developed by Texas A&M University removes both the time and geographic constraints and eliminates the need to maintain delicate equipment underwater, opening a new chapter in coral restoration.
The process begins by "bleaching" the coral sample — removing the photosynthetic algae that live symbiotically within it. The coral is then preserved in a glass-like state inside a specially designed aluminium container and rapidly frozen using liquid nitrogen. It is subsequently slowly rewarmed and rehydrated with seawater within 20 minutes to revive the coral. Thawed coral has been successfully kept alive for up to 24 hours. The research is still in its early stages, and the next challenge is to improve long-term survival rates.
Editor-in-charge: Jenny Tsai
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