So there are many threats facing the oceans around the world from pollution and climate change to overfishing and coastal development. And we need to understand how those threats are having particular effects on marine habitats and species. If we're going to find ways of successfully protecting them. Helen, obviously, coral plays a very big part in that. But what actually is coral, I've never really understood this carl's and reefs. Yes, A lot of people look at a piece of coral perhaps, I think that it's just a dead bit of rock, but in fact it's a living animal. It's a tiny microscopic animal, a relative of enemies that you might have seen in a rocky pool on the beach is around the british isles, but very, very, very much smaller. And they secrete calcium carbonate, chalky skeletons essentially. And they build reefs. So the reefs are built by these colonies of of animals and they're very important for various reasons for the biodiversity hotspot that coral reefs are. But unfortunately, one of the most endangered marine ecosystems we have are the coral reefs in the caribbean where there's been a massive die off in one of the main species or two of the main species of coral that build the reefs. A while ago, I paid a visit to a Mako island in the Bahamas and had the rather wonderful job of going diving with professor john Bruno from the University of north Carolina. Uh you know, sex marine biology for you. You could have done it anyway. What I was there basically to find out more about how and why the reefs of the caribbean are in so much trouble. So caribbean reefs have changed dramatically since the 19 eighties. I grew up in south florida and in the seventies and early eighties you could snorkel over a coral reef and it was just like a golden wheat field of coral. This incredibly complex community that the corals had built up that was inhabited by fish and all kinds of invertebrates. So, a really biodiverse ecosystem that's changed enormously, and you don't have to be a scientist to recognize that. So the corals have all disappeared, there's still some left, but they're far less abundant, that they were just two or three decades ago and there's a variety of causes for that. The sea is warming, leading to a phenomenon called coral bleaching that kills the corals, their sediment pollution in some cases, possibly nutrient pollution. But here in the caribbean, the really big driver of coral losses, coral diseases in one disease in particular, white band disease wiped out what were then the dominant species, staghorn coral and Elkhorn coral populations have plummeted by 99%. So just envision kind of like a Carolina or south eastern US pine forest where the whole force is made up by a couple of dominant species. And then within a 12 month boom, those species are just gonna just completely transforms the landscape. And there's certainly other things going on. But when you lose those keystone species, that is what we call foundation species that built up the whole system, it's fairly easy in this case. 2.2, 1 primary cause. And if we're looking out for disease corals, what what are we looking for? What are the key signs? Yellow blotches on some of the corals are tell tale sign of coral infection. Dead portions of the coral colony where the corals either white because the tissue has died off or they've lost their symbiotic Susan Felli. Some of the coral diseases are these very clear black bands. So usually some sign of infection, either a white or a black band on the coral. So the signs of infection aren't subtle. It's it's quite obvious that something is different. And there's only really a half a dozen common diseases in the caribbean. So it's actually quite easy to identify them. All right. Well, I think it's time we went in and see what we can find. All right. Yeah. So there's really no question that disease was one of the primary drivers of coral loss in the caribbean. And it's still really a big mystery. We don't know what many of the pathogens are that caused the disease. So we don't know what the bug is, what the infection agent is in many cases. And even when we do, we don't necessarily know why it's become so common. And so it's really kind of hard to nail down whether there's a new pathogen, whether the host is stressed out. So, you know, when we get stressed out, we become more susceptible to common colds and all kinds of diseases, or if something about the environment change and either made the host more susceptible or one of those environmental conditions might make the pathogen more what we call virulent. So it's more able to attack the host and cause problems for it. My lab used to focus a lot on nutrient pollution and now we're focused a lot on temperature. How increases in temperature can lead to outbreaks of coral diseases. I'm also collaborating with a coral immunologists to try to understand how corals essentially fight against disease. So corals have very simple immune systems and essentially how they fight off disease. And so some corals are able to fight it off where others aren't just like with people, you know, some people are just naturally resistant to colds and others are really susceptible to them. It's really is still a big mystery why we're seeing these increases in diseases. We really have no idea how to manage them. So we're kind of at the mercy of this, this ongoing phenomenon right now. So we just got back off our die, we're just drying off. And what we saw was to me, it just seemed like a landscape that showed what it used to be. You could see these huge structures that clearly used to be coral. There were big boulders that are now dead, but maybe with a few patches of coral growing on them. Great big spires and turrets and I think must have been these corporate corals, the staghorn and the outcome possibly the outcome, particularly at that site. Yeah, it was incredible. I mean, there's all kind of caves and tunnels. There was so much structure. I felt like I was flying through a city from which humanity had been annihilated. Didn't feel like that. It was just incredible. There was some fish, but I guess not as much as we expect and just know Very little coral, but the skeletons are all there. So the structure they built up over the last three or 4000 years is all still intact. It won't be forever. So you can see exactly what it was like. Just a couple of decades ago, we saw one incidence of disease. There was a white patch growing across that piece of Montasser coral, I think. Yeah, that's right. So it was called white plague disease. So there was a montessori, a quarrel with about six or seven different lobes and all of them were infected by white plague and they're just kind of inching its way across the coral colony, chewing up the tissue. But as a whole, we was ghostly, ghostly landscape. Is there a chance that the corals will come back? Oh, absolutely. I mean, there's been no coral extinctions in the caribbean. I mean, we're threatened with seeing some coral extinctions, possibly even in my lifetime, but all the species are still here. So if we managed to turn things around, I honestly think we could be back to where we were, it might take a century or so. Yeah, we could see near complete recovery.