News | July 12, 2023

Novel Adhesive Offers Path For Reef Restoration Projects

QUT researchers are developing an underwater adhesive gel inspired by nature and investigating ways of using it on coral reefs, including the Great Barrier Reef, to accelerate the natural stabilisation process and reef recovery such as by coral planting.

The two-pronged project funded by the Reef Restoration and Adaptation Program (RRAP), involves researchers from the QUT School of Chemistry and Physics who have developed the gel-like adhesive, and researchers from the School of Earth and Atmospheric Sciences who are conducting laboratory tests to determine the most effective method for gluing underwater coral rubble as well as live coral fragments.

Professor Leonie Barner, who leads the team of Dr Lalehvash Moghaddam, Adrian Baker and Dr Nathan Boase, and are developing the adhesive, said the project evolved out of a workshop she attended where the challenge was put to develop a product that could be used in wide-scale restoration projects on the Great Barrier Reef.

“This adhesive ticks a lot of boxes – it’s biocompatible, biodegradable and it is scalable,” Professor Barner said.

“Now we need to test it on the reef.”

The team have been putting the adhesive through laboratory tests, including for use on a ceramic coral deployment device developed by research partners in the RRAP. The RRAP is funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation.

The QUT researchers have used their adhesive to attach small cement tiles with young corals that slot into the device and are attached using the adhesive, with the ultimate aim being to distribute to the young corals as part of reef re-seeding efforts.

One of the advantages of the adhesive is that, after the coral has time to grow over the ceramic device, it naturally breaks down in a way that does not damage the delicate environment.

While the chemistry team is now planning the first small-scale reef trial with the ceramic devices, other QUT researchers are looking at how the adhesive could be used to help the reef recover from damaging events that produce unstable coral rubble.

Coral rubble is broken and dead coral fragments that are produced naturally and large amounts can be produced by cyclones and wave damage, or can have man-made origins, such as from ship groundings and dynamite fishing.

Rubble stabilisation techniques are needed to secure this loose broken dead coral on the seafloor to allow new corals to attach, regrow and restore the coral reef.

Professor Scott Bryan and postdoctoral researcher Brett Lewis said the adhesive, which is a gel-like material, is being used to mimic a number of marine organisms that, over time, naturally bind and stabilise coral rubble.

“The challenges are that with climate change and the potential for an increasing frequency of bleaching events and cyclones in the future, that when coral reefs are damaged, they won’t have the time to naturally regenerate and recuperate before the next damaging event,” Professor Bryan said.

One possible use for the adhesive being investigated is in sticking together pieces of coral rubble to form more stable masses that can accelerate the natural reef recovery process.

Mr Lewis said the adhesive could be a solution to target coral rubble in areas of high importance and high degradation and encourage the regrowth by glueing and holding together coral rubble.

Currently, methods to rehabilitate coral rubble include adding metal, plastic, or concrete structures to the pristine reef.

Professor Bryan said an advantage of the QUT-developed adhesive was that it could be used to hold coral pieces together while the coral regrew, and that the adhesive was environmentally friendly and sustainable given it partly used plant waste. Mr Lewis said the adhesive would dissolve after a few years leaving no impact on the reef.

Professor Bryan and Mr Lewis are currently trialling methods to determine the best ways of using the adhesive underwater in lab tanks as a precursor to larger-scale field trials. But even at this stage, the researchers are thinking ahead.

“In the future, restoration will likely need to be at larger scale and sustainable – restoration activities that need fleets of boats and lots of divers will be too expensive,” Professor Bryan said.

One possible model for delivering this to key areas of the reef could be through underwater robots, similar to the way QUT researcher Professor Matt Dunbabin’s underwater robots detected crown-of-thorns starfish or delivered coral larvae in another collaborative reef restoration project.

“Once we’ve developed the adhesive, optimised it, and understood how much we need and what strength it gives us on the seabed, then we can work on the process with robotics researchers,” Professor Bryan said.

“This is a new avenue of more sustainable reef restoration.”

Source: Queensland University