Stanford scientists discover method to help coral recover from bleaching

A study from Stanford School of Sustainability shows bleached coral reefs can fully recover in a matter of weeks by fusing them with healthy corals. The research offers some new hope for vulnerable marine ecosystems. For more on this discovery, we are joined by one of the authors of the study. We want to welcome marine ecologist at the Stanford Doerr School of Sustainability, Fiorenza Micheli. Thank you so much for joining us this morning. Good morning, Alice. Happy to be here. I read that this is somewhat similar to organ transplants in humans. You put a healthy coral in direct contact with a sick coral and it's nursed back to health. Is that what this method, how this method works in the simplest terms? Yes, when the temperature rise, corals expel their algal symbiont. And this is called coral bleaching. And then the corals eventually die because they're starved. What we found in this research is that you put healthy corals, not those colorful corals that still have their symbionts in contact with the bleached fragments, they recover just in a few weeks. And they fully recover at a speed and a rate that had not been previously documented. So this is the discovery. And this requires corals to be genetically identical. So this is the main limitation of this method so far. But it does illuminate a mechanism, the algal symbionts transfer, that offer a ray of hope for the future. Right. Yes, I was going to ask, this is an important step, but it doesn't mean that there's an instant cure now to the problem of coral bleaching. You said that they have to be a genetic match, the corals, in order to put a healthy one to fix or nurse a sick coral back to health. That's right. So this is not a solution yet, but it does open the door to possible solutions if the symbionts can be reintroduced in corals. And so we're working on this next step. What is the next step then? How do we scale this so that we can fix this problem of bleached coral reefs? Because we know that's a growing problem as ocean temperatures rise. So research now is focusing on alternative mechanisms of how to reintroduce this algae because the important discovery is that once those fragments are in contact, just for a few days, that process is jumpstart and then continuous with a very fast doubling rate for the algae. So if we can figure out that first step, then this is potentially a very exciting solution for coral recovery. Can you tell us a little bit about your work with this study, the moment of discovery when you realized that you had stumbled on something pretty big? Yes, Danny Collins is the lead author on the study and he's a PhD student in our program. And he had this really new idea of using contact. And the moment, like the aha moment was just days into the first experiment that he did, where he did put these fragments of corals in contact, where you could see the color seeping from the healthy coral. That was the moment when we all felt like, this is amazing. We had never seen this before. And that led to the whole study. Because it's really so simple. It kind of makes you wonder why it took so long to figure something like that out. That's right. A lot of the focus was on preventing bleaching, on what makes coral more resilient, resistant to bleaching. And so this is a new realm of possibilities for coral recovery. Are there other things we can learn and maybe apply from this successful study and these results to the rest of the scientific world, the animal world, or maybe to medicine? Well, it's an exciting new mechanism that, yes, could be applied to perhaps other questions. But right now, we stay focused on coral and coral bleaching because this is a crisis globally and one that we need and all hands on deck to address. Well, it's positive news to hear that there at least is a breakthrough and a possible solution. Fiorenza Micheli, marine ecologist at the Stanford Doerr School of Sustainability and one of the co-authors of this study, thank you so much for speaking with us about this this morning.