Healthy corals help bleached neighbours regain colour: Study
AI generated
asserted
AI → help → colour
The world’s coral reefs face an existential threat from rising seawater temperatures that trigger widespread bleaching, a problem driven by climate change and compounded by 2026’s intense El Nino phenomenon.
asserted
that → face → phenomenon
But a new lab study by scientists at Stanford University finds that simply placing healthy, colourful coral in contact with their bleached counterparts is enough to bring the dying ones back from the brink – a finding that could eventually pave the way for real-world interventions if it can be scaled.
uncertain
it → find → interventions
“It’s stunning,” lead author Daniel Collins told AFP about the outcome of the experiments, recalling the “eureka moment” when he first saw positive results and rushed to his PhD supervisor’s office to share the news.
asserted
he → ’ → news
The paper was published on Oct 14 in the journal Science Advances.
asserted
paper → publish → journal
Coral reef recovery is a highly active area of research, with efforts ranging from using artificial nurseries to rescue reefs to finding and cultivating more heat-tolerant species.
asserted
efforts → range → species
Bleached corals had been largely written off because of their high mortality rate, said Collins – though the new work instead demonstrates they “really shouldn’t be thought of as a lost cause.”
asserted
they → bleach → cause
The Stanford team ran a series of tests with pairs of cauliflower corals, finding five days of contact between healthy and bleached fragments was all it took for the latter to mount a spectacular recovery, at which point they could be safely pried apart.
uncertain
they → run → recovery
The key to the success of the method – which the team informally dubbed “helping hands” – is the transfer of healthy photosynthetic algae, also known as symbionts, from which corals derive their colour.
asserted
corals → dub → colour
Corals are marine invertebrates made up of hundreds to thousands of tiny, soft-bodied organisms called polyps.
asserted
Corals → make → organisms
They have a mutualistic relationship with symbionts, which produce the vast majority of food the corals require, in return for shelter, as well as water and the carbon dioxide they need to photosynthesise.
asserted
they → have → shelter
But in times of heat stress, algae can produce toxins, forcing their hosts to expel them.
asserted
algae → produce → them
Collins said the idea for the experiment came from two sources.
asserted
idea → say → sources
The first was a study that showed plastic waste in the ocean can promote disease in corals by transferring harmful pathogens, which made him wonder whether it would be possible to flip that mechanism on its head with a health-promoting transfer.
asserted
it → show → transfer
The second was a happy accident observed by Stephen Palumbi, the study’s senior author, also at Stanford, who noticed in his lab that a healthy coral and bleached coral had tipped over and were touching each other, and the bleached coral had started to recover.
asserted
coral → observe → other
The scaling challenge
The experiments revealed important constraints.
asserted
experiments → reveal → constraints
Three days of contact was the minimum required for a bleached coral to begin to recover, and five ensured full recovery.
asserted
five → require → recovery
They also had to be in direct contact – a few millimetres apart, and nothing significant happened.
asserted
nothing → have → contact
A major limitation was that the process only worked when the two corals shared the same genetic background, or “genet.”
asserted
corals → work → background
Mixed-genet pairings resulted in the corals deploying stinging cells, a hostile response that can be likened to organ rejection in humans.
asserted
that → mix → humans
Powerful laser microscopy revealed the mechanism: after a day or two of contact, the corals’ tissues began fusing, creating a “nutrient highway” between the pair.
asserted
tissues → reveal → pair
The biggest challenge will be translating an exciting lab finding into a real-world solution.
asserted
challenge → translate → solution
“We likely will not be touching corals to each other on reefs,” said Collins, noting the sheer size of reefs tends to preclude this option.
asserted
size → touch → option
However, it is possible to extract healthy symbionts and culture them – and the team is now thinking about ways to re-introduce them en masse to bleached coral.
asserted
team → extract → coral
This also has the benefit of side-stepping the genetic mismatch problem, which applies to the corals, not the symbionts.
asserted
which → have → corals
The Aporia
