Saving the reefs - with coral larval restoration

Method ensures corals of greater genetic diversity, which will boost their resilience

- Ariel Yu

In the face of rapidly changing marine environments, one coral reef scientist is experimenting with novel ways of coral propagation that could make these habitats more resilient.

Currently, most coral reef restoration activities around the world involve collecting coral fragments from a "wild" reef and growing them in laboratories before transplanting them onto a degraded site. As the coral fragments are genetically identical to their parents, this method of restoration is also known as asexual fragmentation.

But Professor Peter Harrison from Southern Cross University, Australia, is experimenting with coral larval restoration, which produces genetically unique baby corals instead. This method will ensure corals of greater genetic diversity, which will confer more resilience in the face of marine heatwaves and other threats.

The marine ecologist said that while asexual fragmentation is often adopted by non-governmental organisations to help people understand why corals are important to reef ecosystems, it is inadequate for coral reef restoration and has been overwhelmed by the scale and rate of reef destruction.

"Typically (these corals) have limited genetic diversity and therefore low resilience to things such as bleaching impacts. And (the) most recent modelling is showing that this approach is simply not going to be cost-effective for larger scale, kilometre-types of restoration that we need to be doing urgently now," he added.

Commonly referred to in the media as "Coral IVF (in-vitro fertilisation)", the coral larval restoration method is essentially optimising the natural cycle of coral spawning to restore damaged reef systems, and consists of five phases.

The research team first locates diverse breeding corals that have survived recent bleaching events, which indicates that they could be more heat-tolerant than those that did not survive.