An international team including Galway scientists says it has uncovered “new insights” into coral ecosystems which show that different coral species host their own distinct communities of microbes.
The research, which involved a team at University of Galway, shows that coral reefs harbour diverse microbes and produce chemicals with promising potential for future application in medicine and biotechnology.
Coral reefs are often called “the rainforests of the sea”, supporting a third of all marine macroscopic organisms and operating as marine biodiversity hotspots with a wide range of ecosystem services such as ecotourism and nutrient cycling.
The scientific research has revealed that their true diversity lies in their microbiome - invisible to the naked eye.
The coral microbiome is a complex community of bacteria, archaea, fungi, viruses, and algae that live on and within coral tissues, acting as a crucial, functional unit known as the “holobiont”.
The microbiome samples studied in the research, published in Nature, were collected during the Tara Pacific expedition in 2016-2018.
Reef Secrets — Coral formations in Papua New Guinea host diverse microbial communities revealed by Tara Pacific research, highlighting hidden biodiversity and biotechnology potential Photo: Olivier Thomas
The Tara Pacific is an international consortium of marine scientists addressing the challenges oceans face due to climate change.
The scientists’ work has mapped the microbial landscape of reef-building corals at “an unprecedented scale in an ocean which is home to 40% of the world’s coral reefs”, they state.
The international research team analysed microbiome samples collected from 99 different coral reefs across 32 islands throughout the Pacific Ocean.
They reconstructed the genomes of 645 microbial species - more than 99% of which had never previously been genomically characterised.
These microbes are highly specialised partners of their coral hosts, functioning as prolific producers of bioactive compounds.
Dr Maggie Reddy, Ryan Institute, University of Galway, said: “When we compared our findings with microbes found on other reef species, it became clear how little we still know.”
“Of more than 4,000 microbial species identified, only 10% have any genetic information available, and fewer than 1% of the species found only in the Tara Pacific samples have been studied at all. This shows a major gap in our understanding and underlines the need for much more biodiversity surveys, especially in under-studied regions,” she said.
The research highlights a critical, often overlooked dimension of conservation: when coral reefs die, we don't just lose the corals, sponges, seaweeds and fish; we lose a vast "molecular library" linked to the microbial life, she said.
And it noted that biochemical characterisation of previously unknown enzymes and compounds suggests an immense, untapped potential for biotechnology and medicine.
Professor Olivier Thomas, Ryan Institute, University of Galway, said: “The biosynthetic potential of reef-building coral microbiomes rivalled or surpassed that of traditional natural product sources like sponges.”
“Among the biosynthetically rich bacteria in the reef microbiome, we identified previously unknown microorganisms (e.g. Acidobacteriota) living with corals that produce new enzymes with exciting potential biotechnology uses. “
“The research is a clear call to action to protect our coral reefs – not just because of their value as a unique ecosystem – but to preserve the unique chemical diversity poised to enable future scientific breakthroughs.”
Dr Reddy and Professor Thomas will join an international team of scientists on the upcoming Tara Coral expedition this June in Papua New Guinea, funded by the Tara Foundation and associated public and private partners.
During the voyage, they will collect additional marine samples from the region and investigate the factors that enable certain reef-building corals to be more resilient in the face of climate change.
The full study is published in Nature and can be read here.
