Larval Reseeding

The baby coral breakthrough restoring coral reefs.

Larval Reseeding

#The Project

For the first time, researchers have accelerated the formation of new coral colonies on small areas in the Great Barrier Reef using ‘baby corals’ conceived and successfully settled directly on the Reef through a pioneering pilot project funded by the Great Barrier Reef Foundation.

Researchers have successfully piloted small-scale coral restoration on the Reef, with a technique called larval reseeding - capturing coral eggs and sperm during spawning to rear coral larvae before delivering these healthy 'baby' corals onto small areas of reefs. 

During the November 2016 coral spawning, Professor Harrison and his team travelled to the Great Barrier Reef’s Heron Island for the Australian-first trial. They collected vast quantities of coral eggs and sperm during mass spawning, using them to grow more than a million coral larvae, and then delivered the larvae onto reef patches in underwater mesh tents.

Eight months later Professor Harrison’s team returned to Heron Island to discover more than 100 surviving juvenile corals established on the settlement tiles out on the Reef. The research was not without its challenges including the need for careful rearing of coral larval cultures and complex diving operations on the reef by the research team.

#The Process

Parent colonies are collected

Parent colonies are collected

Parent colonies are placed in tanks

Parent colonies are placed in tanks

Researchers take genetic samples

Researchers take genetic samples

Colonies are placed into tanks and monitored

Colonies are placed into tanks and monitored

Corals are ready to spawn when 'budding' appears

Corals are ready to spawn when 'budding' appears

Corals spawn at night under special red light

Corals spawn at night under special red light

Spawn is released and allowed to grow into larvae

Spawn is released and allowed to grow into larvae

Coral spawn is allowed to grow over several days

Coral spawn is allowed to grow over several days

Parent corals are returned back to the Reef

Parent corals are returned back to the Reef

Coral larvae delivered onto reef patches

Coral larvae delivered onto reef patches

Eight months on, the coral grew to 5mm in diameter

Eight months on, the coral grew to 5mm in diameter

#Global significance

The scientist who co-discovered the phenomenon of ‘sex on the Reef’ – mass coral spawning – some 35 years ago is leading the breakthrough which aims to accelerate regrowth of corals.

Professor Harrison’s Great Barrier Reef research builds on the success of his team’s work in the Philippines in an area of reef highly degraded by blast fishing which had similar positive results.

“Our previous studies in the Philippines funded by the Australian Centre for International Agricultural Research, showed that corals can grow from microscopic larvae to dinner plate sized adult colonies within three years and they were able to sexually reproduce. This work at Heron Island is the first step towards proving we can apply these techniques on the Great Barrier Reef,” Professor Harrison said.

He sees great promise in the mass larval restoration approach and says it has the potential to make a difference to reef recovery on a larger scale using natural coral spawn slicks that contain many millions of larvae from different coral species.

“This is the first project of its kind on the Great Barrier Reef to successfully re-establish a population of juvenile corals from larvae settling directly on the reef,” said Southern Cross University’s Professor Peter Harrison, lead researcher on the project.

“This pilot study carried out on Heron Island shows that our new techniques to give corals a helping hand to conceive and then settle, develop and grow in their natural environment can work on the Great Barrier Reef.

“The success of this new research not only applies to the Great Barrier Reef but has potential global significance – it shows we can start to restore and repair damaged coral populations where the natural supply of coral larvae has been compromised.”

#Working with marine park management

In successive years, the team has worked closely with the Great Barrier Reef Marine Park Authority to implement this ground-breaking pilot project.

“Innovative science like larval reseeding is one piece in the puzzle of protecting the Reef into the future,” Great Barrier Reef Marine Park Authority Chief Scientist Dr David Wachenfeld said.

“In recent years, the impacts of climate change on the Great Barrier Reef have undoubtedly accelerated, as we saw with back-to-back years of coral bleaching.

“It is vital everyone keeps working to address climate change and build the Reef’s resilience, and for restoration strategies to be developed that can work over large areas.

“We need to be more proactive and intervene to give the Reef a better chance and that’s why supporting leading-edge research like this is a priority for the Great Barrier Reef Marine Park Authority.

“The success of these first trials is encouraging – the next challenge is to build this into broader scale technology that is going to make a difference to the Reef as a whole.”



#Project partners

Fitzgerald Family Foundation
Southern Cross University
Great Barrier Reef Marine Park Authority