Probiotics found to boost coral survival

Researchers have proven that feeding coral a dose of good bacteria increases their overall health and tolerance to stresses related to climate change, such as rising water temperatures.

Coral reefs are critical ecosystems that are essential to the future of our planet. As noted by Anna Marsden, Managing Director of the Great Barrier Reef Foundation, “Not only are coral reefs home to 25% of the ocean’s marine life but they also support the livelihoods of 1 billion people globally.

“However, we are increasingly seeing corals becoming stressed due to threats such as rising water temperatures, which is causing them to become prone to infections and less likely to survive.

“People may be surprised to find out that, just like us, corals rely on a host of good bacteria to help keep them healthy and, just like us, the balance between good and bad bacteria is often disrupted in times of stress,” Marsden said.

“Probiotics have been widely and successfully used to improve both human and animal health; however, their use in marine ecosystems has been largely unexplored until now.”

Now an international research team, led by Professor Raquel Peixoto from the Federal University of Rio de Janeiro, has shown in a laboratory setting that feeding corals beneficial probiotics increases their overall health and improves their chance of survival during heat stress.

“We fed the corals with beneficial microorganisms, which is like feeding them probiotic yoghurt full of good bacteria,” Prof Peixoto said.

“Then we ran numerous stress tests on the corals, and time and time again the corals that had received the probiotics were in better health than those that had not.

“This finding is an exciting breakthrough in boosting the ability of coral species to survive in times of stress and help them cope with a changing climate.”

Microscopic view of corals eating the probiotics.

Prof Peixoto’s research team are currently running tests on different species of corals in the world’s largest artificial ocean (the Biosphere 2) in Arizona, and in laboratories at the University of Hawaii, to refine which groups of good bacteria are the best for each species. They are also investigating new methods to scale up the application for use on coral reefs, such as delivering parcels of slow-release probiotics to targeted reefs during times of heat stress.

Coral in the lab being stress tested.

Marsden said pioneering science such as this provides hope for the future of the Great Barrier Reef, which is currently weathering its third mass bleaching in just five years.

“This technology can be used by Queensland research institutions such as the Australian Institute of Marine Science to help boost the health of the corals reared in their National Sea Simulator before they are transported out to the Reef as part of their reef restoration projects,” Marsden said.

“The survival rate of these corals once they are out on the Reef is currently quite low, so giving them a health boost while they are in the Sea Simulator will boost their chance of survival.

“It will add another tool to Reef researchers’ toolkits as they commence the world’s most ambitious reef restoration and adaptation effort (Reef Restoration and Adaptation Program).”

Top image courtesy Great Barrier Reef Foundation. Photographer: Gary Cranitch, Queensland Museum.

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