Coral Breeding Key for Great Barrier Reef Recovery

Southern Cross University's Peter Harrison and his Coral IVF team are racing to develop the hardier next generation of corals in the wake of mass coral bleaching earlier this year across the Great Barrier Reef.

The University's Coral IVF team, comprising postdoctoral researchers, PhD candidates and staff members drawn from Australia, Philippines and Europe, are united not only by a shared passion for the breathtaking scale and beauty of the Great Barrier Reef and other global reefs but the urgent need to support coral and reef recovery.

From modest beginnings with a small trial site in 2016 near Heron Island, off Gladstone, this spawning season the Coral IVF team is working with colleagues from the Reef Restoration and Adaptation Program (RRAP) at five locations across the Reef - including the southern, central and northern sections - to scale-up the solution.

Some are helping share the knowledge with traditional owners, marine industries and tourism operators to train them on using the innovative coral larval restoration technique.

At Lizard Island, north east of Cairns, researchers working with colleagues from CSIRO are set to trial new techniques aimed at increasing the efficiency of settling larvae onto Reef areas, thereby increasing recovery rates for coral communities damaged by increased sea temperatures that led to the recent mass coral bleaching.

"Now, more than ever, there is a sense of urgency with this work to scale up by scaling out: to expand the number of reef sites and get more partners and people involved. Monitoring surveys have clearly shown that many areas of the Reef have been hit hard by mass bleaching," said Distinguished Professor Peter Harrison.

"Having teams operating in four regions along more than 1000km of the Reef, and adapting the technique to suit the skill level or the location while all using the same Coral IVF technique to generate many tens of millions of larvae, is exciting.

"At the same time, it's rewarding to see this project grow in scale to generate many millions more larvae by replicating sexual natural reproduction processes and increasing larval supply to support the Reef's natural regeneration process."

As November's supermoon awed sky gazers, Southern Cross University's coral larval restoration team was busy preparing for coral spawning: the annual underwater 'snowstorm' of trillions of eggs and sperm bundles released by many of the Reef's coral species in synchrony under the cover of darkness, triggered by the lunar event.

During spawning last week, the team worked around the clock to collect a high diversity of these egg and sperm bundles from multiple coral spawn slicks.

Now, in specially-designed nursery pools floating on the sea surface, more than 100 million larvae bred from corals that survived the bleaching are being reared. Over the next few days, teams will release the larvae to settle and create baby corals on damaged sections of Reef, and the best adapted of these newly settled corals will grow to adulthood to help bring new life to these Reef areas in future.

Professor Harrison is increasingly concerned about the expanding impacts from climate change.

"We're continually working out ways to improve the efficiency of the larval restoration technique and use surviving heat-tolerant corals to create new populations that are more likely to survive the next bleaching events and adapt to rapidly-changing reef conditions as the impacts of climate change increase," said Professor Harrison.

"The global community must recognise the urgency of the climate crisis and rapidly transition to renewable energy production to better manage climate impacts on reefs and all of Earth's life support systems, otherwise we will continue to lose corals and healthy reefs at faster rates that exceed the capacity for natural recovery.

"There are fewer breeding corals on many reefs due to recent bleaching events, so each of the surviving corals becomes more important and therefore we want to make sure we're breeding from as many of them as possible so we can increase the genetic diversity of the many millions of larvae that we're releasing back onto the Reef system.

"We expect these coral offspring to have increased tolerance for higher-than-average sea temperatures. Once they reach breeding size and sexual maturity, they'll pass on these qualities to the next generation of corals.

"If we don't support the process of natural selection by focussing on the survivors and rapidly expand the scales of successful coral restoration, we're going to lose everything."

This research is part of the Reef Restoration and Adaptation Program which is funded by the partnership between the Australian Government's Reef Trust and the Great Barrier Reef Foundation. Partners include the Australian Institute of Marine Science, CSIRO, Great Barrier Reef Foundation, The University of Queensland, QUT, Southern Cross University and James Cook University.