Explainers · 6 April 2021

What is Coral IVF?  

This world-leading technique could be key to restoring and repairing damaged coral populations on the Great Barrier Reef and around the world.

What is Coral IVF?

Coral IVF is a world-leading technique to grow baby corals and use them to restore damaged coral reefs.

Our researchers capture coral eggs and sperm, called spawn, from healthy reefs and rear millions of baby corals in specially-designed floating pools on the Reef and in tanks. When they are ready, we deliver them onto damaged reefs to restore and repopulate them.

Researchers deploy coral babies onto damaged reefs.

How do corals reproduce?

Many coral species on the Great Barrier Reef are known as “broadcast spawners”. They reproduce by sending enormous quantities of spawn into the water, where the eggs are fertilised and turn into free-swimming tiny larvae.

When the larvae are mature enough, they fall to the sea floor and settle. If they are lucky, they attach to a suitable surface and turn into a coral polyp. They grow by producing more polyps and begin life as new juvenile corals.

During annual spawning events, our researchers collect a huge volume of excess spawn from reefs with a healthy coral population, that would otherwise have drifted out to sea, or been eaten. They put it into floating nurseries on the Reef where larvae form over a number of days. When they are mature enough, we deliver them to damaged reefs where they can attach and grow.

Corals spawn just once a year in a synchronised mass breeding event.

Does Coral IVF work?

Our research team, led by Southern Cross University’s Professor Peter Harrison and CSIRO’s Christopher Doropoulos, began trialling Coral IVF on the Great Barrier Reef in 2016 and the early results are promising. Recent field trips to our sites have shown the transported corals have grown well on the Reef and are now the size of dinner plates. We expect them to spawn this year, helping boost the local population further.

The early results of Coral IVF are promising. Credit: Gary Cranitch, Queensland Museum

Why is Coral IVF important?

Coral reefs around the world are facing a growing number of threats including climate change, which leads to increased water temperatures. Heat stress is one of the causes of coral bleaching and, while bleached corals can recover, severe bleaching events can kill large areas of coral reef. The Great Barrier Reef – the world’s largest coral reef – has suffered three mass bleaching events in the past five years.

To help our Reef recover, we have more than 100-Reef-saving projects underway right now and the world’s largest coral reefs program. We are developing, testing and deploying new techniques to protect and restore coral reefs at scale and help them resist and adapt to a changing climate. Coral IVF is just one part of this innovative work, which can be scaled up and deployed on coral reefs around the world.

Find out more about Coral IVF here.