Restoring coral reefs is a global challenge that has been attempted around the world, with previous research achieving varying levels of success at small and localised scales. CSIRO, together with other leading Australian research organisations, is assessing the prospect of implementing restoration at the scale of the entire Great Barrier Reef.
Coral reefs are suffering from major global and local disturbances
Coral reefs provide ecosystem services, such as fisheries and tourism, worth more than $6 billion per year in Australia alone. Yet a combination of global and local stressors are degrading the state of coral reefs and severely reducing their long term resilience and capacity to recover.
Coral restoration initiatives have previously been limited to highly localised efforts, but upscaling restoration to ecological meaningful scales is necessary in order to provide the capacity to safeguard reefs until global stressors such as coral bleaching from human induced climate change are reduced.
Approaches and implementation of industrial scale coral reef restoration
We are testing the effectiveness of large scale restoration using population models, field trials, and remote sensing approaches.
Population models have been developed using the best available demographic information from the literature. Models compared two potential large-scale restoration strategies: the harvesting, development, and release of wild coral spawn slicks onto a target reef, with the transplantation of gravid coral colonies to provide a seed population and local source of larvae.
Along with our industry partner Van Oord Dredging and Marine Contractors, and Delft University, we conducted a feasibility study to test fundamental components necessary for the large-scale harvesting and long distance transportation of wild coral spawn slicks. The study tested our ability to locate and concentrate spawn slicks for collection, the survival of coral embryos following pumping, comparison of survival using two different industrial scale pumps and the capacity to culture the harvested embryos through to competent larvae in a 50,000 litre aquaculture facility on board a tug boat. Funding was provided through an Advance Queensland Small Business Innovation Research grant.
Understanding of the abundances and movements of coral spawn slicks is needed to quantify their potential for sustainable harvest should this approach be implemented in large-scale restoration efforts. Working with members of our remote sensing team, we are examining the spatial extent and locations of coral spawn slicks throughout the Great Barrier Reef.
Comparing the costs and benefits of harvesting wild coral spawn slicks with transplantation of gravid coral colonies has indicated (in published research) that the controlled release of coral spawn slicks has the potential to achieve large-scale restoration of coral communities with low impact technology at low cost per colony.
Our feasibility study was conducted in November-December 2018. Initial outcomes demonstrate we have the ability to successfully contain wild coral spawn slicks, harvest them onto a large vessel using two pumping approaches, and culture them until the larvae are competent to transition to new colonies on the reef.
The fact that this can be done using large commercial vessels shows that this approach can be used to transport corals across the entire length of the Great Barrier Reef. The next stage of the project will aim to upscale the approach even further and apply large scale restoration providing hundreds of millions of larvae to reefs needing restoration.