Research offers glimmer of hope for threatened coral
Grim forecasts for the world’s dying coral reefs have just become a little brighter with the release of new research from the United States.
The study, published in the Biological Sciences journal, has found coral may be able to survive better than previously thought in warming sea temperatures.
The researchers used a new, more in-depth method to examine the genetic make-up of 39 coral species.
They discovered that all of those species can in fact host at least two different forms of algae – or what is scientifically referred to as a clade – including one that is associated with higher thermal tolerance.
But while Australian experts have acknowledged the findings as significant, they say it merely “buys us time”.
Marine scientist Dr Ross Hill from the University of New South Wales explains the research:
“Previously it had been thought that a lot of coral species could only harbour one type of clade,” he said.
“But what I was really surprised to see was that all the coral species that they studied had more than one clade in at least one replicate… so each species looks to have the potential to have more than one, which is a new finding.”
Clades are the algae that live inside corals and provide them with nutrients.
Clade D, which the researchers detected a background element of in every coral species they examined, can tolerate higher levels of heat.
“Without a mechanism to cope with rapid environmental change, coral bleaching will likely continue to result in widespread declines in coral cover,” the study concludes.
“Symbiotic flexibility may provide one mechanism by which corals can respond to changing environments, and data shown here suggests that this mechanism may be more widespread among diverse coral species than previously assumed.”
Dr Ross says many of the species they examined are found around Australia, but he says the study really only provides a glimmer of hope.
“The hope is that these clade D background amounts, if they’re in a high enough density, they could remain in the coral, remain healthy and provide some energy to prevent the coral from dying if the sea temperatures rise,” he said.
“So if they have more clade D they will hopefully be less susceptible to bleaching.
“There is the potential that it could give some corals a bit more tolerance to rising temperatures, but only for a limited time.
“The reason is because sea temperatures are continuing to rise and even this thermo-tolerant clade D – it might be half a degree, maybe one degree more tolerant – but at the rate sea temperatures are rising eventually we will still reach the limit of clade D.”
And there are other dampeners.
The presence of clade D in coral can make them more susceptible to diseases and limit the rate at which they grow.
Nonetheless, Dr Hill says it is a significant finding.
“It is an important finding simply because we didn’t know that all these coral species had the potential to harbour this kind of algae.”