Algae clearing supports transplanting of coral babies at Magnetic Island

The scientists have been clearing algae that has been choking sections of the reef, making room for Professor Peter Harrison’s team from Southern Cross University to deploy millions of coral larvae – defying inclement weather to resettle the coral babies on the reef in a process known as ‘coral IVF’.

It’s almost 38 years to the day at the same location since Professor Harrison and colleagues discovered the mass coral spawning natural phenomenon. The discovery radically changed scientific views about how corals on the Great Barrier Reef, and other reefs around the world, reproduce.

The first coral spawning of the 2019 season began in the evenings of October 18 and 19 and since then the Southern Cross University team has collected the coral spawn and grown millions of coral larvae in rearer pools for an experiment to resettle the babies on the reef.

Professor Harrison said the algae problem was particularly bad on inshore reefs including Magnetic Island, located eight kilometres off the Townsville coast, due to poor water quality, increased nutrients and bleaching events.

“Our previous extensive reef trials have shown that supplying coral larvae to degraded reefs can rapidly restore breeding coral populations within a few years, and for this new collaborative project we’re examining how effective the combination of algae removal and larval restoration can be,” Professor Harrison said.

“I’m pleased by the initial rates of larval settlement we’re seeing so far and we’ll be monitoring the reef sites over coming months to see how many new juvenile corals become visible next year.

“It’s exciting to be back working at Magnetic Island attempting to restore corals on these degraded reefs, as I first thought of this idea back in the early 1980s when we discovered mass coral spawning on the Great Barrier Reef at this location.

“This project is a great example of reef research and management collaboration, with Southern Cross University combining forces with James Cook University’s algal removal team led by Associate Professor David Bourne, and Craig Humphrey at AIMS (Australian Institute of Marine Science) SeaSim where the team reared millions of larvae after the corals spawned.”

The collaborative partnership also involves the Great Barrier Reef Marine Park Authority, EarthWatch Australia, Reef Ecologic, and Port of Townsville Limited. Funding is from Southern Cross University, Mitsubishi CSR, the National Environmental Science Program Tropical Water Quality Hub and the Great Barrier Reef Foundation. 

Coral spawning

Professor Peter Harrison describes mass coral spawning as billions of coral eggs and sperm being released into the sea simultaneously and spectacularly like an ‘underwater snow storm’ which occurs at night after full moons in late spring or early summer.

The discovery of mass coral spawning not only earned Professor Harrison and colleagues a prestigious Eureka Prize for Environmental Research, but sparked his idea about how corals could be restored on a mass scale using millions of larvae, following a catastrophic bleaching event.

Coral IVF

For the past seven years Professor Peter Harrison has been successfully developing ‘Coral IVF’ on the Great Barrier Reef and in the Philippines as a method to restore dying coral reefs. The process involves Professor Harrison and his team collecting coral spawn, growing millions of coral larvae in enclosures on the reef and sometimes in tanks on land, before releasing larvae onto dead and damaged reef areas to stimulate the recovery of degraded coral reefs.

Prior to this, Professor Harrison has successfully trialled the process on other degraded reefs in the Philippines and multiple sites on the Great Barrier Reef. This year Arthur Bay reef at Magnetic Island, just off Townsville, was selected for the study for the early part of the coral spawning season.

Cluster of baby corals newly settled (Credit Peter Harrison)

Rearing coral larvae at AIMS (Credit Mark Walsh)