This Underwater Robot Will ‘Squirt’ Coral Larvae onto the Great Barrier Reef to Save It

The LarvalBot is an experimental technology that could revive damaged and dying parts of the Great Barrier Reef.
Scientists grew coral larvae that an underwater robot will disperse over the Great Barrier Reef.
Coral spawning. Image: Gary Cranitch/Queensland Museum

Millions of tiny corals on the Great Barrier Reef have a new mommy—an underwater robot christened the “LarvalBot.”

The black-and-yellow submersibles, which are roughly the length of a skateboard, are part of an ambitious project to conserve the Great Barrier Reef by seeding it with coral larvae, which can grow and help to regenerate damaged areas. The iconic ecosystem has suffered numerous coral bleaching events over the last two decades, overwhelmingly attributed to climate change.

Matthew Dunbabin from the Queensland University of Technology

Matthew Dunbabin from the Queensland University of Technology operates the LarvalBot. Image: Queensland University of Technology

“We aim to have two or three robots ready for the November spawn. One will carry about 200,000 larvae and the other about 1.2 million,” Matthew Dunbabin, a professor of science and engineering at Australia’s Queensland University of Technology, said in a statement on Thursday.

Coral bleaching can occur when too-warm water temperatures cause them to expel their zooxanthellae—tiny photosynthetic algae that symbiotically inhabit coral tissue, and supply it with up to 90 percent of its energy. Without these organisms, coral appear white and skeletonized. Their absence also makes coral vulnerable to mortality. A 2016 ocean heatwave around the Great Barrier Reef was associated with mass die-offs of 30 percent of its coral population.

But sometimes corals can bounce back, and that’s where LarvalBot can help.

In 2016, scientists at Australia’s Southern Cross University collected coral eggs and sperm from the Great Barrier Reef during its annual November spawning event. They cultivated the spawn into a million coral larvae, and returned them to the wild where 100 survived and continued to grow.

Now these same scientists, along with experts from the Queensland University of Technology and the Great Barrier Reef Foundation, are using similar IVF (in vitro fertilization) techniques to robotically fertilize the endangered reef. Robots, the team claims, can fertilize reefs more efficiently than human divers. For example, the robots allow for “up to a 100-times increase” over previous methods, they said in a news release.

A rendering of how the LarvalBot will disperse coral larvae over damaged parts of the Great Barrier Reef.

A rendering of the LarvalBot seeding the Great Barrier Reef with coral larvae. Image: Queensland University of Technology

The team recently collected hundreds of millions of coral spawn to rear into batches of baby corals. They’ll mature in floating ocean enclosures and, once developed (the process takes roughly one week), LarvalBot will disperse them over key areas of damaged reef.

“We concentrate the larvae and put some of these into LarvalBot to gently squirt the larvae onto dead reef areas allowing it to settle and transform into coral polyps or baby corals," Peter Harrison, director of Southern Cross University’s Marine Ecology Research Center, said in a statement.

The semi-autonomous robots will follow preselected paths across the reef while someone manually triggers the larvae release. Each robot is capable of covering more than 16,000 square feet per hour.

“The surviving corals will start to grow and bud,” Harrison said, “and form new colonies which will grow large enough after about three years to become sexually reproductive and complete the life cycle."

It’s unclear right now how successful the mission will be. But Harrison is confident in the technique, saying it has “the potential to revolutionize coral restoration on reefs worldwide.”

The LarvalBot is essentially a repurposed RangerBot—an underwater robot trained to identify and kill the invasive and coral-eating crown-of-thorns starfish that has infested the Great Barrier Reef. The robot, which received funding from Google, kills the starfish by injecting them with a lethal substance.

The coral larvae release is slated to occur during the Great Barrier Reef’s massive spawning event this month.