A floating film 50,000 times thinner than a human hair, a device which shoots salt into clouds and machines that churn seawater are just some of the ideas being put forward to repair the Great Barrier Reef at an Australian-first conference in far north Queensland.

Andrew Negri from the Australian Institute of Marine Science said a biodegradable "sun shield" was one of several ideas being discussed at the Great Barrier Reef Restoration Symposium being held in Cairns this week.

He said the project, led by AIMS and the University of Melbourne, had only been trialled in labs so far, but he hoped to test the film on the reef within the next two years.

"The great thing about the film is it is only a molecule thick so you can swim straight through it and it'll just keep self-forming," he said.

"It essentially uses about half a bucket of calcium carbonate to protect an entire hectare of coral reef, and for the film-forming component we need less than a teaspoon of material to keep that carbonate at the surface of the ocean.

"The next step would certainly be to trial it in very large tanks in the National Sea Simulator, then we'll apply for permits to take it out on the Great Barrier Reef and do small scale trials out there.

"But we need to talk to the public to get social license for an experiment like this."

Mr Negri said while the film was not designed to cover the whole reef, it could help prevent coral bleaching at key sites.

New technology to protect Australia's world-famous coral is being discussed at the first Great Barrier Reef Restoration Symposium in Cairns. ( Supplied: Indian Ocean Imagery )

'Like a snow cannon that shoots salt into the clouds'

Another idea being discussed by the hundreds of experts, scientists and engineers at the symposium is the concept of cloud brightening.

The project is part of the Reef Restoration and Adaptation Program led by the Australian Institute of Marine Science.

Program director David Mead said that while addressing climate change was vital, there was a shift in the science community with more experts asking what can be done to fix the current damage.

He said cloud brightening involved encouraging clouds over the reef to deflect sun back into space, so less heat and light reached the coral below.

Symposium organiser David Mead says more scientists are now looking at creative ways to help coral survive climate change. ( ABC Far North: Anna Hartley )

"It seemed [like a whacky concept] to me at first. The team have been looking at using a very fine nozzle to pump small droplets of salt water at the rate of several billion per second," he said.

"The water vaporises and you're left with a salt particle which will float around, and if you can introduce those into the system you can increase the amount of sunlight reflected back.

"It's called cloud brightening because, from above, the cloud appears brighter."

Mr Mead said the process was similar to a snow cannon and would use the same device with a modified nozzle to pump sea water into the atmosphere.

"To apply it as a method on the Great Barrier Reef is a new idea and it is early days," he said.

"We need to look at if it influences weather patterns, and trials need to occur.

"The reef is battered and bruised, but it's beautiful, and Australia has a huge breadth of scientists that can be brought to bear on this challenge.

"Climate mitigation has to be a priority but some of the techniques on the table here [in Cairns] can help us buy time."

Hundreds of experts, scientists and engineers are in far north Queensland looking at innovative ways to tackle coral bleaching. ( Peter Harrison: Southern Cross University )

Trial to start on reef restoration project this summer

A machine that mixes water on the reef is another solution being put forward.

Suzanne Long from the Reef and Rainforest Research Centre said a slow turning impeller would mix water vertically to lower its temperature.

"We're looking at trialling it on the reef this summer, so in December," she said.

"We're moving into a period where none of the old ways of doing things are going to work anymore.

Suzanne Long is in Cairns this week presenting new ideas at the symposium. ( ABC Far North: Anna Hartley )

"We've had a very hands-off approach to managing the reef in the past, but we no longer have that luxury."

While many of the ideas being proposed at the conference may seem extreme, Ms Long said outside-the-box thinking was key to saving the reef.

"Some of the ideas sound really 'out there' until you talk to the scientist championing it and you realise that some of the ideas we'll actually need," she said.

"We have to develop ways to help the reef survive and adapt to increasing temperatures that will continue to occur over the coming decades."

Coral fragment hanging from a 'tree' as part of a study to re-plant coral on the Great Barrier Reef. ( Supplied: Reef Ecologic )

Coral tree nursery to double after early signs of success

Those proposing unusual ideas at the symposium are invited to visit Fitzroy Island off the Cairns coast to see a similarly innovative project successfully saving coral on the Great Barrier Reef.

Rob Giason from the Reef Restoration Foundation said the coral nursery project — which involved small pieces of coral being suspended from a tree-like structure under water — is set to almost double in size after initial signs of success.

He said the project involved resilient coral growing on the trees being replanted onto damaged reefs.

"We're very encouraged by what we see. We started with around 24 corals and within seven months we're up to about 400," Mr Giason said.

"Some of those corals are growing up to 90 per cent of their original size, so it's really encouraging."

Four more coral trees will be built on the site this week, taking the total to 10.

Mr Giason said it was another an example of how a seemingly large leap of an idea could work to help save the reef, and he hoped it encouraged scientists working on equally creative endeavours to continue.