"Coral IVF" Could Save Dying Great Barrier Reef, Pilot Study Shows

Early efforts have been successful.

Australia’s Great Barrier Reef is in trouble. It’s taken a serious beating over the past few years in the form of mass bleaching events, including a single heat wave that led to the loss of 29 percent of the reef’s coral. But scientists think they might have found a solution, and early results suggest it could work, and they’re calling it coral IVF. Yeah, you read that right: in-vitro fertilization for coral.

Peter Harrison, Ph.D., the director of the Marine Ecology Research Centre at Southern Cross University in Australia, is leading the project, which just saw its first results. He and his colleagues seeded test reefs at Heron Island and One Tree Island, off the coast of Queensland, with millions of coral larvae 18 months ago. In a recent survey, they found a major increase in the numbers of new coral growing there.

“There’s a very clear outcome, the higher the numbers of larvae that you put into the reef system, the more coral recruits you get,” Harrison tells CNN. “The pilot studies at small scales are giving us hope that we will be able to scale this up to much larger reef scales.”

Bleaching event currently occurring on the Great Barrier Reef. But coral IVF could help it recover.

D. Kauffman

To conduct coral IVF, Harrison and his colleagues do something pretty similar to what’s done in human IVF. During an annual coral spawning event, they collected millions of coral sperm and eggs. They then grew these gametes into coral larvae and redistributed them onto the reef. By doing this, the scientists give the coral a much higher rate of successfully latching onto a reef than the floating spawn would have if left to its own devices.

Harrison was inspired by his colleagues in the Philippines who have found success with this technique in restoring shoreline reefs that had been devastated by dynamite fishing. In that particular case, the remaining corals simply couldn’t produce enough new larvae to repopulate the damaged reef, leading to a cycle of declining overall fertility. And as a result of die-offs caused by climate change, the Great Barrier Reef is at risk of a similar decline. After all, an unhealthy population can’t sustain a healthy population. It needs some help.

When the water gets too warm, coral lose their zooxanthellae and turn white. 


Early results of pilot studies on the Great Barrier Reef suggest that IVF is working. The best-case scenario, reports Harrison, is that these lab-grown larvae will colonize the reef and grow to reproductive maturity, increasing the number of new larvae that can, in turn, reproduce and grow more coral. And while the technique won’t stop coral from dying off due to bleaching events, which scientists say are caused by rising ocean water temperatures, it can help the reef recover more quickly after they occur — which they almost certainly will continue to do.

“The Great Barrier Reef, like many reefs around the world, has suffered from almost catastrophic loss of the coral community, and what this larval restoration hopes to do is to enable the process of coral community and therefore reef recovery to occur at much faster scales than would occur naturally,” Harrison tells CNN. This year, Harrison and his team plan to scale up their approach to see if this plan could become a feasible large-scale management technique.

This project is just one possible solution that scientists have devised to protect and restore reefs, including robots that kill reef-eating sea stars, but all of them hinge on whether humans can slow the pace of global climate change. After all, while coral IVF can improve the rate at which reefs bounce back after catastrophe, without comprehensive efforts to stem climate change, it’s just a bandage on the bigger problem.

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