 Welcome to Healthy Planet, the show for people who care about their health and the health of our planet on the Think Tech Livestreaming Network series. I'm your host, Dr. Grace O'Neill. Joining me today is Wendy Kover, a coral biologist. Today we're gonna talk about coral health. So let's get into it. Wendy, can you tell us about what kind of role coral play in the health of the oceans and what is it that the coral actually do and tell us are they living? Just tell us more about the coral. Sure, absolutely. So yeah, corals are alive. They're animals. They're really rather unique animals and that if you think of sort of the old school animal, vegetable, mineral distinction, in a sense they're actually all three of those. They're technically animals. They have tentacles that capture food, sting food and bring it into their mouth and digest it but there are many, many of those different little polyps on a colony of coral. So they're a colonial animal and they secrete a skeleton. So that's where the mineral part comes in. So they have different shapes. They might be branching, they might be mounding, all different types, many, many species and growth forms and the vegetable part of the equation comes in because they have tiny little symbiotic algae that live within their cells, their single-celled algae. They're called zuazenthele and those little algae are friendly to the coral and they photosynthesize and some of the food that the algae make goes to the coral. So they get a home and the coral gets some food. So they're really incredible organisms that build these skeletons that then make whole huge reefs all together over time. And so all of the barrier reefs offshore where the waves are breaking, they're from the Great Barrier Reef to even just smaller reefs offshore and they create the coral sand, the beautiful white sands of Hawaii. It's actually incredible like how many functions corals have within tropical ecosystems. They're really important for storm protection from waves from their structure and the structure of the reefs also provide homes for all kinds of other animals for all that incredible diversity that we see on coral reefs. Corals are providing the structure and the homes for those fish and invertebrates and other creatures that live on them. So when is the most common time for these coral to feed? Because oftentimes you're maybe snorkeling or diving and you're not necessarily seeing them feeding. When would be a good time if someone wanted to see these corals feed? When would be a good time for them to observe something like this or is it very hard to observe that? Yeah, if you go diving or snorkeling at nighttime, you're much more likely to see a coral with its tentacles extended. It varies a little from species to species, but yeah, they tend to extend their tentacles at night because that also tends to be when the food they wanna capture, the zooplankton is most prevalent, they come up at night. And so more likely to see those tentacles at night, generally during the day the tentacles are retracted, but you can still see that coral light structure. Sometimes they're very, very small, but where that polyp resides in the coral, lots of them in the colony. Nice. And how do they get all the colors that they have? There are many different colors. There are many different colors, different shades of brown and green, sometimes pinkish or bluish. Mostly those colors come from that symbiotic algae that I mentioned, their zoos and fillets. There are many different types of zoos and fillets that the corals can bring into themselves to live symbiotically with them. And usually it'll vary by species, but they're even within a species, there can be many different types of zoos and fillet and slightly different colors that the corals can have as well. So mostly that color is coming from that symbiotic algae. And how long have you been studying coral? I started studying coral in college on a foreign study program. And I first started doing it for work, not long after college when I joined the Peace Corps and I was working on the small island nation of Neway in the South Pacific. And I was working for the fisheries department there and it was really amazing experience. How about you didn't you study coral here in Hawaii? Can you tell the viewers about that experience? Yeah, so for my dissertation work, I worked out on Midway Atoll, which is way out in the Northwestern Hawaiian Islands and what is now Papa Hanau Mokoke, a national monument, renational monument. And I looked at species interactions on the reef. So basically like how herbivores, which are certain types of fish or urchins that eat algae, big macro algae, not the little symbiotic algae I was talking about earlier, but big algae that you can see that grows on the reef. The herbivores will eat that. And that can actually be a great thing for the corals because that macro algae can overgrow and smother the corals if there's too much of it. And so those herbivores are really, really helpful for the corals. They serve a really important function on the reef. So how is the reef affected when there are no herbivores anymore? I guess, you know, with overfishing and everything. How does that affect the reef? It's a big issue, definitely. It's one of the three really big issues affecting coral reefs. Because those herbivores are so important in keeping the algae grazed down. And on a healthy coral reef, you really won't see any hardly any macro algae, maybe one species podinas somewhat regularly. But for the most part, you really don't see it. A healthy coral reef has lots of hard corals, maybe some soft corals, some sponges, but not so much algae. And that's because the herbivores are grazing that algae down. And if you overfish the herbivores, which has happened in a lot of places now, one really notable story that happened in Jamaica, the fish herbivores, mostly parrot fishes and surgeon fishes, they got fished out. And the final remaining herbivores, which were an urchin, the long-spined urchin, those got hit by a disease and they got wiped out. And after that, a hurricane struck and wiped out a bunch of the corals. And what grew in its place because there weren't any fish herbivores anymore was a lot of macro algae. And the corals just couldn't recover with all of that macro algae there. And so there was what they call a phase shift from a coral-dominated system to an algae-dominated system. And so that's sort of the biggest concern with overfishing is that when you lose that really important grazing function, you can actually like completely change what loads on the reef when there are other disturbances or things that go on. When you control the overfishing though, I mean, I guess you can have some regulations, but here a lot of people spearfish too. I mean, how do you think that impacts it? Is that less of an impact? Is it more of an impact? Because I know the spearfishers, they might be more mindful of taking fish that aren't reproducing first or so I've heard, but I don't really know how that affects the reef. Yeah, well, first of all, fishing regulations can have a really big and important impact. And they have in Hawaii in a lot of places. There are some no-take areas where fish have recovered really strongly. There are some areas that protect herbivores, specifically herbivorous fishes like parrotfish and surgeonfish and those have recovered really well and are doing their important duties on the reef. And though with regard to spearfishing, it's an interesting question because spearfishing is very specific. Like the person is down there and you can target exactly what you want and avoid what you don't wanna catch. So that can be great if implemented in a thoughtful manner. Spearfishing also can just make it really easy to get a lot of fish especially. For example, a lot of people, at least in the past would spearfish at night when the parrotfish are sleeping and they kind of just hang out in one spot under a coral or something resting. Super easy to go down, spear them. And so it's almost like too easy to get the fish and to wipe out the fish in an area. And so that's where you can kind of get into trouble with spearfishing as if there's kind of too much of it because it is in some senses an easier way of targeting fish that you wouldn't be able to get otherwise. Yeah, but it's interesting because when I was in Peace Corps on Niue, there are a lot of cultural traditions that they have going way back. And interestingly, one of them is that spearfishing is taboo. You're not allowed to do it on the island at all. It's a longstanding tradition. I don't know how far back it goes. But one really interesting consequence of that that I noticed when living and diving there was that the fish are not afraid of you at all. They're huge parrotfish that are just swimming right really close to you, munching on the reef. They have no fear whatsoever. And then go to some other place where there is spearfishing or especially that had been fished recently and the fish take off as soon as you're there. And sometimes like, it's really terrified. So it's really interesting how that had sort of totally unanticipated effects. I would never have thought about that, but it can also make a difference for divers and snooklers in the experience of being on a reef in terms of how afraid or unafraid the fish are. Fish are kind of smart actually, after all. Yeah, they are. Talk about the two other factors that you kind of mentioned that was the first factor, the fishing. And then talk about the two other factors that are affecting the coral reefs, if you could. Yeah, absolutely. They're sort of the big three, they call it. And that's climate change, pollution, and overfishing. And so we talked about overfishing a bit already. I can talk about the other two if you want as well. Yeah. Okay, so with climate change, things are getting warmer. And we know that in the oceans as well are getting warmer. So one of the biggest problems for corals is that they are really used to a particular temperature range. And when those temperatures get hotter than that for an extended period of time, it's very stressful to them and to that relationship with their symbiotic algae. And so something happens called coral bleaching, which you may have heard of. And that's basically where the coral turns white. It's like it's been bleached by bleach. There's no bleach involved. But that's why it's called coral bleaching. So the coral turns white and we already talked about how the color of the coral comes from that symbiotic algae that it has within itself. And so it turns white because it expels that algae because of the stress like that relationship is no longer beneficial for the two. And so it gets rid of the algae and it becomes a bleached coral. And if the conditions don't cool down pretty quickly, the coral will die because it needs to have that symbiotic algae to live for a long period of time. And so that warming is a really big, big problem for coral reefs, especially because it's projected to have more and more warming over time and coral bleaching events are getting much more frequent worldwide. And this is a worldwide issue, not just in Hawaii. Yeah, affecting corals everywhere. So yeah, climate change in terms of warming, also in terms of acidification. And I don't even know if we want to go into that, but. That is another issue. And then pollution is a really big issue for coral reefs. And there's sort of, I guess, forming types of pollution that can come into reefs. You can get sedimentation coming in. So that's like soils, clays, any kind of land sediment runoff coming into the water. And the problem with that is that, that will basically smother the corals. It can outright kill them if there's enough of it. It can also just decrease the light that's available to the corals because of all those sediments in the water, suspended sediments. And so that makes it harder for the algae to photosynthesize and give the coral food. So sedimentation is a problem for reefs. Also nutrients. So nutrients like phosphates, nitrates, which you find a lot in fertilizers. You find them naturally as well in the sediments, but especially in fertilizers from agriculture, from sewage, from agricultural animal waste. So all those things will bring nutrients into the water. And nutrients, we know are great for plants, right? That's why we put them on our crops. But the plants on the reef are that, the macroalgae that I was talking about earlier that compete with the corals, right, for space. And so you're basically feeding that macroalgae and encouraging its growth instead of the coral's growth. And it makes it harder for the corals to grow, to recover for the little, the young little coral recruits to come in and grow. So nutrients are a problem. So what have we done? We've done sedimentation, we've done nutrients. Chemical pollution is definitely an issue. It's probably one of the least studied things, but there are a variety of chemicals from herbicides and pesticides to petroleum products and things that can get onto the reef and... How about the sunscreen? Because that was a lot. Yeah, sunscreen is one of those chemicals. So chemical sunscreen and those chemicals, and they're still studying all of them, but at least one or two have been shown already to kill corals. Yeah, and so using like a mineral sunscreen instead or a rash guard is really great. Oxide. Yeah, the zinc oxide mineral sunscreens, yeah, are a lot more reef friendly. So those are the ones that will be labeled reef friendly. If you see a sunscreen labeled reef friendly, that's why, because the other sunscreens have those chemicals that can harm corals. And can you tell us, I noticed that when I went to American Samoa to visit you that the coral reef is a lot nicer there, there's more colors than we have here in Hawaii. Do you think it's just because our population is larger here and more trash, more runoff, or is it just because it's a different location? Is it the age of the island? What affects the reef, I guess? What other factors are there that are... Yeah, yeah, it's a really interesting observation. And I think, I mean, probably a large part of what you're seeing is just the fact that Samoa has a much higher diversity of corals naturally than Hawaii does. And that's simply because of geography because it's a lot closer to the center of coral diversity, which we call the coral triangle, which is around Indonesia area. And so the further you get away from that center of diversity, the fewer corals there are, the fewer different types of corals on a reef. And so Hawaii has less diversity, so it's less likely to have all the different colors and different coral types. It can still have good coral cover. And also because of that isolation that Hawaii has, it actually has more endemic species of corals and of fish and invertebrates, which is really neat. So endemic species are found nowhere else on earth. Oh, that's true. So that's kind of a really cool thing about Hawaii's reefs is they're about 20% are so endemic species. So yeah, they just have kind of some different things going on. And in Samoa, there are some absolutely gorgeous reefs that have been well-protected and haven't been subject to pollution and other problems. And there are reefs that have been subject to pollution and bleaching and disease and that have been mostly killed off. So it's a mix. And I think you see that mix in Hawaii too. Like there are some places that are pretty well cared for and are doing well in other places that are really, really struggling. I know there wasn't there, I think you told me there was a problem with overfishing in America Samoa, because so there weren't as many fish there. How did that affect their coral reef? Yeah, it's interesting that you noticed that and yeah, it's true there has been a fair amount of overfishing. You see it in a lot of places. And yeah, it's hard to say exactly how it's affected the reef. In some places the reef has still managed to be pretty good, even though it's fairly overfished because those areas don't really have any nutrient input or pollution coming in and haven't been hit by any major disturbances like a hurricane or something. But in other places, yeah, the reefs actually have been taken over by algae and that's kind of been a combination of the overfishing and the nutrients together, just encouraging that all the growth and not having enough workforce to get rid of it. And so we've absolutely seen that in American Samoa in certain areas because of the overfishing. And so yeah, it can happen in more areas to really helping it doesn't. Yeah, and how about the way, I mean, it must affect when you kill like the predator at the top of a food chain. I mean, if there's a lot of sharks being killed, how does that affect the coral reef? Yeah, having predators in an ecosystem in any ecosystem is really important. They tend to target more diseased or weaker individuals and that tends to keep the whole system healthier. So having predators in general is indicative of a healthier ecosystem. Everything just functions better when you have those predators there. A lot of the weaker individuals, yeah. Well, thank you so much. We're out of time when we have to put it up now. So I'm Dr. Grace O'Neill. This is Altea Planet on the ThinkTech livestreaming network series. We've been talking with Wendy Cover. Thanks to all of you for being here. Thanks to Michael, our broadcast engineer and the rest of our crew at ThinkTech for hosting our show. And thanks to you, our listeners for listening. I'll see you on June 23rd for more of Healthy Planet on ThinkTech, the show for people who care about their health and the health of our planet. Our next show will be about vegan nutrition and nutrition education for medical students with Dr. Michael Clapper. If you have ideas for the show, please contact me at healthyplanethinktech at Gina.com. Check out my website at greasonhawai.com for more information on my projects including future show guests. Anyway, I'm Dr. Grace O'Neill. Thank you for watching. Aloha, everyone. Thank you so much for watching ThinkTech Hawaii. If you like what we do, please like us and click the subscribe button on YouTube and the follow button on Vimeo. You can also follow us on Facebook, Instagram, Twitter and LinkedIn and donate to us at thinktechhawaii.com. Mahalo.