Feeding coral reefs with a dose of "good" probiotic bacteria helps them tolerate rising sea temperatures, as new research shows.
Scientists say this is the first time they have proven that feeding corals with useful probiotics improves their overall health and improves their chances of surviving heat stress.
In laboratory tests, corals, to which beneficial microorganisms were added – similar to feeding probiotic yoghurt to humans – were in better health than those that were not.
Laboratory-grown corals that receive probiotics in their diet may have a better chance of survival if introduced into the natural reef.
Research gives hope for the future of coral reefs, including Australia's 1,400-mile Great Barrier Reef, which will survive its third mass bleach in just five years.
According to scientists, coral bleaching killed about 30 percent of the Great Barrier Reef's coral in 2016 and only went through the third mass bleaching event this year.
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Coral in the laboratory as part of experiments supported by the Great Barrier Reef Foundation, an Australian non-profit organization
The laboratory experiments are supported by the Great Barrier Reef Foundation, an Australian non-profit organization that aims to save the world's largest coral reef system.
"People will be surprised that corals, like us, rely on a variety of good bacteria to stay healthy, and just like us, the balance between good and bad bacteria is often upset in stressful times," said the Great's management director Barrier Reef Foundation Anna Marsden.
“Probiotics have been used extensively and successfully to improve human and animal health, but their use in marine ecosystems has been largely unexplored to date.
"Saving the reef is a big task, and this groundbreaking research project is just one of the ways we can make a real difference with our partners."
The file photo taken in October 2016 shows the bleaching of corals on the Great Barrier Reef in Australia, a World Heritage Site
The researchers experimented with injecting beneficial microorganisms into corals before ingesting them through their zooplankton prey.
Professor Raquel Peixoto of the Federal University of Rio de Janeiro conducts probiotic tests on various types of coral in the world's largest artificial ocean – "The Biosphere 2" – in Arizona and in laboratories at the University of Hawaii.
This helps refine which groups of good bacteria are best for each type of coral.
They are also investigating methods to increase application for use on coral reefs, e.g. B. Delivery of slow-release probiotic packages to targeted reefs in times of heat stress.
The underwater speakers played recordings of the sounds of a healthy reef – including the sounds my shoals of fish, shrimp and other reef residents made. Pictured young cardinal fish swimming around healthy corals on the Great Barrier Reef
In humans, slow release probiotics spread bacteria in the intestine over a period of about half a day, and this treatment could give the microorganisms a better chance of survival if they do their job.
The probiotic technique is used by research institutions in Queensland, such as the Australian Institute of Marine Science, to improve the health of corals grown in simulators before they are transported to the Great Barrier Reef.
"The survival rate of these corals once they are on the reef is currently quite low, so if they get a health boost in the sea simulator, their chances of survival increase," said Marsden.
Although coral reefs cover less than 0.1 percent of the ocean floor, they are home to 25 percent of the ocean's marine life.
Picture received Monday April 10, 2017 of bleaching damage on the Great Barrier Reef. Recent aerial photos from the Australian Research Council's Center of Coral Reef Studies have shown that only the southern third of the Great Barrier Reef escaped coral bleaching without damage
They are home to the world's greatest biodiversity of all ecosystems and offer food for marine life, protection against flooding and the preservation of the fishing and tourism industry.
In the past five years, reefs around the world have suffered from coral bleaching events due to the rise in global surface temperature caused by greenhouse gas emissions from human activities.
They are under increasing stress due to threats such as rising water temperatures, making them susceptible to infection and less likely to survive.
Coral bleaching occurs when the oceans get too warm and corals throw off colorful algae.
With rising sea temperatures, warmer waters pollute corals and release algae that live in them. This gives them up to 90 percent of their energy.
This event causes the colorful coral communities to turn white – an effect known as coral bleaching.
Bleached corals are not dead, but have a higher risk of death, and these bleaching events are more common under climate change.
While some coral reefs can recover over time, algae dominate others.
Over the years, repeated bleaching of corals due to ocean warming has disrupted marine ecosystems around the world.
This reduces the availability of food and protection for many marine animals that rely on these coral structures, resulting in a loss of biodiversity.
Australian scientists warned earlier this year that the Great Barrier Reef had gone through its third mass bleaching event in the summer of this year within five years in the summer of the southern hemisphere.
Aerial surveys have shown that the northern, central and southern areas were formed by coral bleaching last summer
Aerial surveys of 1,036 reefs have shown that the northern, central and southern areas are affected, according to Terry Hughes, professor of marine biology at James Cook University in North Queensland.
For the first time, all three regions of the world's largest coral reef system were bleached.
"With summers getting hotter, we no longer need an El Nino event to trigger mass bleaching on the Great Barrier Reef scale," said Professor Hughes, who described the probiotic technique of the bacteria as "another secret weapon."
The Australian Government's Research Council's ARC Center of Excellence previously estimated that only the southern third of the Great Barrier Reef escaped coral bleaching unharmed.
Warm oceans cause coral bleeding
Corals have a symbiotic relationship with tiny marine algae called "zooxanthellae" that live inside and feed them.
When the sea surface temperatures rise, corals drive away the colorful algae. The loss of the algae causes them to bleach and turn white.
These bleached conditions can last up to six weeks, and while corals can recover when the temperature drops and the algae return, heavily bleached corals die and become covered with algae.
In both cases, it is difficult to distinguish healthy satellites and dead corals from satellite images.
This bleach has recently killed up to 80 percent of corals in some areas of the Great Barrier Reef.
Bleaching events of this kind take place four times more frequently worldwide than before.
The ARC Center of Excellence in Australia previously estimated that only the southern third of the Great Barrier Reef escaped coral bleaching without damage.