We're kicking off World Oceans Day early with this research story about how coral reefs are similar to humans -- their health is tied to their microbiomes

NSF's Weather or Not!

We're kicking off World Oceans Day early with this research story about how coral reefs are similar to humans -- their health is tied to their microbiomes

National Science Foundation


Diving deep to study the coral microbiome.

Interviewer: Charlie Heck

Interviewee: Monica Medina

Charlie: Tiny, tiny organisms that you can only see with a microscope: They’re in the air, soil, rocks, water, pretty much everywhere. Some thrive in searing heat while others do best in the freezing cold. I’m talking about microbes and we’re made up of millions of them, collectively called our microbiomes. Our very own ecosystems within us. Some microbes cause disease in humans, plants and animals, others are essential for a healthy life. In the oceans, the microbiome of coral plays an important role in the health of coral reefs.

Monica: They’re a large collection of organisms from the tree of life and there is very little known about them.

Charlie: That’s Monica Media, an NSF-funded marine biologist at Penn State University.

Monica: We don’t understand the nutritional dynamics between the coral and the bacteria that live on them. We know there is some bacteria in the gut of the corals and they’re probably exchanging compounds back and forth and we don’t know much about what is happening there. If we can start to do experiments with these organisms, have them in their cultures, sequence their genomes we can see how they complement each other, metabolically.

Charlie: The best studied members of the coral microbiome are the Symbiodinium, photo synthetic algae that live within the tissues of many coral species.

Monica: We have started to learn about some bacteria that seem to also be symbions and people for a long time did not consider that there were other symbions associated with the coral. But now we know that there may be some nutrient exchange between the coral and the bacterial species and in some cases they may be secreting antimicrobial peptides or other chemicals that deter other nasty microorganisms that could land on the coral and make it sick. They are many, many things that these microorganisms may be doing that we just don’t know that may be more beneficial than not.

Charlie: Bacteria in the coral microbiome perform functions vital for its survival. Some microbes help corals by fixing nitrogen, which can be a scarce resource on the reef. Others produce antibiotics that ward off potential pathogens. Without their microbiomes, corals could not persist. A coral reef is always in flux -- If it’s stressed out, it will be more prone to harboring pathogenic microbes.

Monica: Coral reefs are endangered and corals in particular are very important organisms in the reef because they are the ones that build them, where other organism find homes in their little crevices and sediment and even coral rubble. So because they are threatened by multiple stressors associated with climate change and coastal development, they are getting sick and they are being impacted by thermal stress and ocean acidification that is altering this microbiome. And since we know very little about it, we can’t really tackle the problem. We only understand the symbiom that uses the photosynethis that helps build the reef structure. If we want to try to help alleviate the pressure on these ecosystems, it would be really helpful to understand the associated microbiome.

Charlie: That’s Monica Medina, her research on coral microbiomes is funded by aims to describe the composition of the coral microbiome and to determine its role in coral physiology and health.

Charlie: I’m Charlie Heck, co-editor of Science360’s News Service and co-host of the Super Science Show, at the National Science Foundation.

If you have any questions about this story or suggestions for interviews about super cool NSF-funded science, email me at editor@science360.gov.