Pioneering research on cross-species coral hybrids, inoculations with protective bacteria and even genetic engineering could provide a lifeline for the ‘rainforests of the oceans’

New super corals bred by scientists to resist global warming could be tested on the Great Barrier Reef within a year as part of a global research effort to accelerate evolution and save the “rainforests of the seas” from extinction.



Researchers are getting promising early results from cross-breeding different species of reef-building corals, rapidly developing new strains of the symbiotic algae that corals rely on and testing inoculations of protective bacteria. They are also mapping out the genomes of the algae to assess the potential for genetic engineering.

Innovation is also moving fast in the techniques need to create new corals and successfully deploy them on reefs. One breakthrough is the reproduction of the entire complex life cycle of spawning corals in a London aquarium, which is now being scaled up in Florida and could see corals planted off that coast by 2019.

“It is a story of hope, rather than saying ‘it’s all going to die and there’s nothing we can do about it’,” said Prof Madeleine van Oppen, from the Australian Institute of Marine Science and the University of Melbourne.

The researchers, who presented their cutting-edge work at a conference at the University of Oxford last week, acknowledge that such serious biological interventions on coral reefs could be seen as controversial or risky.

“But it is too late to leave them alone, given the pace at which we are losing corals,” said van Oppen, who said the broad aim is to speed up natural evolutionary processes. “I don’t have any problem with that. We have already intervened in the marine environment tremendously and there is no part where we cannot see human influence.”

Coral reefs are critical ecosystems in the oceans, hosting more than a million species and sustaining natural services worth $10tn a year, including providing vital food for 500 million people. But climate change is heating the oceans and causing corals to bleach: reefs could die out as early as 2050, with perhaps half already gone.

Facebook Twitter Pinterest Dead and dying coral covered by seaweed after coral bleaching at Lizard Island, north of Cooktown, on Australia’s Great Barrier Reef. Photograph: Ocean Agency

The global coral bleaching catastrophe from 2014 to 2017 was the worst in recorded history. “That was a real wake up call,” said van Oppen, with the the world’s largest – Australia’s Great Barrier Reef – losing half its corals in two years, despite being seen as the best managed. Current restoration methods, which simply replant the same nursery-raised corals, are no longer enough, she said: “ it is only a matter of time before the next heatwave hits. It is very urgent that we develop these new interventions.”

One of the most promising is coral hybrids, and new experiments by Van Oppen’s team have shown that corals adapted to cooler water can be crossed with other species from warmer regions so that the hybrids withstand heat better. “I am very excited because the results are so promising,” she said, adding that she expects the forthcoming research paper to be the first on the topic.

Facebook Twitter Pinterest Madeleine van Oppen Photograph: David Russell/University of Melbourne

The team have now applied for a permit to test the hybrids on the Great Barrier Reef, potentially within a year. “I am hopeful that in the 2018 spawning, which is late in the year, we can place some of them out in the field,” van Oppen said.

Another approach is to toughen up the symbiotic algae that live in the coral animals’ tissues and provide them with food. Leela Chakravarti, one of van Oppen’s team, pushed the algae through 80 generations in the lab, each time selecting for the most heat tolerant, and produced symbionts that could survive 31C water temperature. The experiment proved the concept and now the team looking for ways for the corals themselves benefit from the rapidly evolved algae.

Corals, like most animals, also rely on beneficial bacteria – probiotics – and Raquel Peixoto, at the University of Rio de Janeiro in Brazil, has shown that inoculating corals with a cocktail of 10 hydrocarbon-eating bacteria helps them survive oil spills.

Van Oppen’s team is about start similar work but using bacteria that mop up the damaging reactive oxygen molecules produced when corals are under stress and start to bleach. The promise here is that it might one day be possible to spray probiotics on a reef to strengthen it – a much simpler approach than growing and planting corals.

Genetic engineering is also being explored, as it may be a fast way to get protective genes into corals and symbiotic algae. “We are starting to see what is possible in the laboratory,” said van Oppen and the group are already decoding the genomes of some symbionts.

Facebook Twitter Pinterest Living coral is shown under a microscope at the Hawaii Institute of Marine Biology on Coconut Island, Hawaii. Scientists are preparing to transplant laboratory-enhanced coral onto reefs in Hawaii in hopes that the high-performing specimens will strengthen the overall health of the reef. Photograph: Caleb Jones/AP

Getting both regulatory and public approval to deploy such techniques in the wild is vital, she said. But Prof Alasdair Edwards, at the University of Newcastle, UK, thinks that will be a challenge: “I think the public are going to be very iffy about that, and many scientists are too.”

While super corals are starting to be produced in the lab, if they are to help restore reefs they will have to be successfully delivered in large numbers. But new techniques are being rapidly developed in this area too.

Facebook Twitter Pinterest Jamie Craggs Photograph: Horniman Museum

In November, the first research to replicate the entire life cycle of a spawning coral in a closed system was published by James Craggs, who did the work at the Horniman Museum in London, thousands of miles from the source reefs in Singapore and Australia. As the Guardian spoke to Craggs in Oxford, his team at the museum were busy hybridising the two corals.

A key aim of Craggs’s work is to accelerate research on the mysterious factors that control spawning – a combination of temperature, sunlight, lunar cycles and more. In the oceans, this often happens on just one day a year and is therefore incredibly hard to study. But Craggs is now aiming to produce a spawning event every month and his techniques are being scaled up in Florida, where two of eight large greenhouses have been built to house breeding tanks.

“The work is game-changing,” said Scott Graves, at The Florida Aquarium’s Center for Conservation. “It allows us to spawn corals on site, create multiple spawning events across the year and drastically speed up restoration work to ensure the survival of Florida’s reef.”

Craggs said he expected these tank-grown corals to be going into the waters off Florida in the next two years. He also believes there is a need to act: “We really do need to intervene. We have caused this issue and morally I feel we should do something. There is an awful lot of work that goes on in reforestation: is this any different in principle?”

Facebook Twitter Pinterest A tray of enhanced coral is placed on a reef during a practice run for future transplants in Hawaii’s Kaneohe Bay off the island of Oahu. Photograph: Hugh Gentry/AP

Other new technology presented at the Oxford conference included three-pronged concrete bases to grow corals on in tanks, which can then be wedged into reefs without time-consuming ties or glue. Another is a “badminton technique” for delivering small tank-grown corals to trawler-damaged habitats deep in the Mediterranean. “The fan shape of the coral acts like a badminton shuttlecock and slows the descent, allowing a good landing,” said Maria Montseny, at the University of Barcelona.

Great Barrier Reef: scientists identify potential life support system Read more

The damage to reefs around the world is on a vast scale, while expensive restoration efforts will always be relatively small, But scientists have discovered that in reef systems, just a small part of the reef is often the source of many of the new larvae, so focusing efforts there will have a much bigger impact.

However, all the restoration efforts are only buying time for coral reef survival in the face of global warming – rising temperatures will overwhelm all reefs unless checked. “It is a stopgap measure until we solve the greenhouse gas problem,” said Edwards. “Without that, we are on a hiding to nothing.”