Plastic Podcast Episode 19: How do plastics impact coral reefs?

Dive into plastic pollution's impact on deep sea coral reefs with host Clark Marchese and expert Dr. Lucy Woodall. Discover the vital roles of coral reefs, from supporting marine life to protecting coastal communities, and learn about the threats posed by plastics, from disease transmission to structural damage. Dr. Woodall shares insights from her research and recent expeditions, emphasizing the urgent need for global action to protect these critical ecosystems. Tune in to understand the intricate connections between plastic pollution, climate change, and marine conservation, and explore solutions for a sustainable future.

Episode Guests: Dr. Lucy Woodall

More information about Dr. Woodall here

Browse Dr. Woodall’s publications on Research Gate

Visit the Nekton website here

More information about the episode and the Plastic Podcast

Episode Transcript  and more information on the Pine Forest Media Website

Follow Pine Forest Media on Instagram @pineforestmedia

Hosted, produced, and edited by Clark Marchese 

Cover art and PFM logo by Laurel Wong. 

Theme music by Tadeo Cabellos 

Transcript:

[00:00:09.790] - Clark

Hello, and welcome back to another episode of Plastic Podcast, the show that tells the science and the story of our relationship with plastic. I am your host, Clark Marchese, and today we are going deep sea diving into a discussion about plastic and deep sea coral reefs. If you've been listening to the show for a while, you know we've talked about plastic pollution in many different contexts. But today, we are taking a closer look at how plastic is affecting one of the most vital and diverse ecosystems on our planet, coral reefs. To tell us all about this, I found a researcher named Dr. Lucy Woodall, who is an Associate Professor at the University of Exeter and a Principal Scientist at Necton, a UK-based NGO. She's been studying the oceans for years and asking critical questions about the patterns of life in the sea and how human activities are impacting these systems. In today's episode, we'll hear about her recent deep sea expedition. We'll learn why coral reefs are essential for our oceans and our coastal communities. We'll talk about Dr. Woodwell's discoveries on how plastic is impacting coral reefs from disease transmission to structural damage and why there is a need for further research on deep sea Reefs.

[00:01:31.270] - Clark

Without further ado, let's get started. All right, Dr. Woodall, welcome to the show. Maybe I'll have you start by introducing yourself and telling us a bit about your research.

[00:01:53.270] - Dr. Lucy Woodall

Hi, great to talk to you, Clark. I'm Dr. Lucy Woodall. I'm an Associate Professor at the University of Exeter, which in the southwest of the UK, and I'm also Principal Scientist of a UK NGO called Nekton. I guess I would define my research as being interested in trying to understand patterns of life in the ocean. Really asking three questions: what's there, why is it there? How have we, as humans, impacting those plans?

[00:02:25.810] - Clark

Those are definitely the types of questions we need to be asking. Also, when we were trading emails before this, you mentioned you just got back from a deep sea expedition. Can you tell me about that project?

[00:02:37.190] - Dr. Lucy Woodall

Yeah, well, I was incredibly fortunate to be out in South Africa for the last three weeks, working with an amazing NGO out there called Wild Oceans. We were looking at some reefs at about 60 meters off the Coast in Durban, two of their marine protected areas. This project itself is multiple different projects. This is just one small work package, and it really relates the ocean to the communities on land. I was just doing a very small part of the amazing projects that they're doing out there, trying to ensure that there is resilience against climate change within the biological and human communities along the coastline.

[00:03:18.810] - Clark

Amazing. Well, today we're going to be talking about plastic and coral reefs, which is one area where you focus a lot on in your research. I'm curious, how did you get interested in this topic?

[00:03:29.360] - Dr. Lucy Woodall

Yeah, I guess I started working on plastics back, 2015 now, so quite a long time ago, and it was totally by accident. I had come back from an expedition in and around the Southern Ocean area on the Southwest Indian Ocean Ridge. I was meant to be looking for nematodes, tiny worms in sediment. My background was in genetics, and I was meant to be looking at the genetics of these small creatures and identifying them. The short story there is that we found lots of new species. About 95% of what we found was new to science. But while I was going through and looking at these very small worms under the microscope, I was also seeing blue, yellow, green, I need fragments and mostly fibers. I hadn't looked at deep sea sediment before, and I was quite confused about what these things were. Of course, these days everyone would go, Well, of course, they're microplastics. But it wasn't the first thing that came to mind. I I spoke to some colleagues and I was like, I'm finding these things, and I really want to know what they are. After a while, I was like, I think the only things that could be this vibrant is plastic.

[00:04:42.760] - Dr. Lucy Woodall

I did a little bit of research and connected with researchers that had got there before me. They'd be already looking for microplastics in the ocean. The study that we ended up doing was looking at their ubiquity in the deep sea. So saying, Hey, look, we find them in coastal waters, we find We find them on the beaches, we find them in shallow waters and on the surface, but actually they are sinking right down to the depths, and we're finding a lot of them. So for example, in the areas that we were looking, we were finding about 25 fibers in a teacup. I'm British. I can use teacup as a size, right? So 25 fibers in a teacup. So it gives you an idea of just how much we're finding. So now my research really is based on thinking about what are some of those places across our planet in our wonderful ocean that we as humans really haven't seen so much before. I'm very fortunate with the work that I do with Nekton, partnering with nations, so that together we can answer some of these questions about some of the deeper reefs. So beyond the scuba diving decks of about 30 meters.

[00:05:51.310] - Dr. Lucy Woodall

But when we get that little bit deeper, equipment gets harder to find that can access these spaces. So myself, along with many others, are now really looking at those deeper reefs to see if we can understand them a little bit more to ensure that they don't get left behind in really important management of protection.

[00:06:11.740] - Clark

Okay, so I have two follow-up questions based off of that. The first is, how deep is deep sea considered? And then the second one is, where do we find most of our coral reefs? Are most of them in the deeper seas or more close to the coastline?

[00:06:27.710] - Dr. Lucy Woodall

Well, you asked me two questions, but actually, that's a lot of questions in there. Let me start with your first one. 200 meters is traditionally the definition of deep sea. You can see already there's a bit of a challenge. To 30 meters, we can use scuba gear. Then by 200 meters, that's when deep sea science happens. There has been this bit of a gap until, I would say, the last 15, 20 years, but not many people are really thinking about this 30 to 200 meters. While, of course, 200 It is very important, and it's that definition because that's where we don't see any light from the surface getting down, and those conditions are very different to what we see in surface waters. That's what my work really focuses on, is trying to input some more data into what we call deep reefs. You can say mesophotic reefs, mesophotic coral reefs, that's middle light. You can call them the deeper reefs, rarephotic rare light. I don't really mind what you call them as long as they're in our public consciousness as actually really important areas. Now, the second question you asked me is actually a much harder one to answer.

[00:07:40.210] - Dr. Lucy Woodall

Coral reefs, where are they found? Well, typically our shallow water coral reefs, about 1% of our planet, including about a quarter of our marine organisms, so super diverse, they're across our coastlines and we've either them, if we've been lucky enough to live there or go on vacation or even see them on TV and in the films. Vibrant life. I'm like a kid in a candy store. I want to see all that stuff. It's amazing. That's what we see in vibrant, healthy coral reefs. They are home to huge diversity of life and nurseries. They're also really important for protection for coastlines. However, shallow water tropical coral reefs are only one type of coral We get coral reefs right down in the deep sea as well. Different types of coral, but they're still coral. I think a neat summary, really, to your answer is we've got our tropical coral reefs. We know they're important, but are We have a vast array of other coral habitats that are all the way into our deep, deep, dark sea, which we're only just now starting to understand.

[00:08:55.970] - Clark

Okay. Well, thank you for saying that. It's good to keep in mind because a lot of attention probably goes on to the shallow reefs because, well, for a number of reasons, perhaps mostly because they're easier to access, but we cannot forget about the others. Before we start talking about how plastic is impacting these coral reefs, maybe it would be a good idea to fully establish how important they are to our ecosystems. You mentioned a couple of their functions briefly, but can you just give us an understanding of the ecological functions that coral reefs play out and why they're important to the ocean ecosystem?

[00:09:27.450] - Dr. Lucy Woodall

Coral reefs are incredibly important habitats. We say they are habitat-forming. In and around them, other things live. What we're thinking is they're creating homes for lots of other marine species. This is particularly important because often we'll find our coral reefs in areas with quite low nutrients in the water. Other things maybe such as algae, are not necessarily growing there. Coral can only live there because they've got their great little algae that live in the corals themselves, the Zuzanthes, which do the photosynthesis. They don't necessarily need lots of nutrients in the water because they can survive through energy coming from the sun. I mentioned shelter, so they're like houses for lots of marine creatures. They're also nurseries, so some of our smaller fish in their area. This includes things that we as humans eat. This is important both for our fisheries, and that's livelihoods and economic benefits as well. Then also there's this protective function. As we can imagine, storms, the number of storms and the intensity of storms are increasing due to the impacts of climate change. Actually, the energy in the ocean is dissipated as they go through coral reefs. So this structure is really important to be able to protect our coastlines, and that includes, of course, the important vegetation along the coastlines, but of course, also human communities as well.

[00:11:01.440] - Dr. Lucy Woodall

I think you can tell just from that massive range of functions, their value. Of course, I am only talking about our tropical coral reefs as opposed to those that are in our deep sea. But what we can say is those that are in our deeper reefs that are just a little bit deeper following down from our shallow water coral reefs, have many of the same functions. It's really important, therefore, for us to think of this as a continued space.

[00:11:31.450] - Clark

Then how is plastic messing all of this up? There was an article that you published that focused on three ways. Maybe we can go through them one at a time. The first one talked about how plastic and coral reefs can quickly spread through food webs. Then the second, we have disease transmission, and finally, structural damage. Maybe we can walk through each one of these.

[00:11:51.510] - Dr. Lucy Woodall

Yeah, I can talk about them briefly. My researcher hasn't specifically addressed any of those. I am going to be calling on other people's research, so they'll have to take an apology from me now if there's any nuances that I don't have right. But firstly, I want to say that plastics is just one stressor in our coral reefs. We have many of them. I've already mentioned the consequences of climate change. Coral reefs also are really impacted by any additional nutrients in the water, such as outpouring from sewage. We also have fishing and lots of unsustainable fishing practices that are going on. It's really important for us to be thinking about these global impacts and local impacts on what we can do to bring that stresser level down because that's what our coral reefs are really suffering from. Specifically, when we're thinking about plastics, we think about how did they get into the system and how could they potentially impact organisms. That, of course, is really different depending on the life history and the life cycle of the organism that we're thinking about. But also, let's think about coral reefs not just as the coral themselves, but actually as all the organisms that are within that ecosystem.

[00:13:08.820] - Dr. Lucy Woodall

Of course, within that, you've got sponges and other things that live in and around the coral and on the sea floor, and they're filter feeders. They're pulling in all these microplastics. You've also got fish, some small fish all the way up to really big predators like sharks. These are being impacted. They're ingesting these microplastics and also not just microplastics, but some large pieces of plastic as well. There's a number of studies out there that have looked at fish stomachs and found the huge numbers of plastics in these spaces. However, if we find plastics internalized in an organism. We can't automatically say that it's problematic, right? Because just because we find something there doesn't mean to say there's an impact. What we need to do, and what researchers are doing right now, is actually making those connections from saying, Hey, look, we're finding these things in animals across the planet, to saying, What are the processes and what is the consequences of having these microplastics internalized in these animals? This could be multiple things. It could be the polymer itself. It could be additives that are put into the plastics as they're being made. But also, as soon as plastics get in the environment, there's chemicals that are adsorbed into those plastics.

[00:14:28.890] - Dr. Lucy Woodall

That could be anything. Because we know that we've been talking here about pollution from plastics. I mentioned a little bit from sewerage, but there's lots of different chemicals that are polluting our oceans in different quantities and in different places. I would encourage everybody to think about when you see plastic, to also think that there's other pollutants in that environment as well. I like to almost think of plastics like a gateway opportunity.

[00:14:59.160] - Clark

Right. Actually, on our very second episode ever, Abby Barrows told us how microplastics in the ocean act as a sponge, soaking up all the other chemicals in the ocean, not to mention the chemicals in the plastics themselves, which we've talked about on the show as well. We've also covered biomagnification and bioaccumulation. So the high diversity ecosystems, like a coral reef, is a way for the plastic chemicals to move through the food chain really quickly.

[00:15:25.400] - Dr. Lucy Woodall

I think your next question was regarding disease transmission and what could happen there. Again, they've been very, very early days. But some work that I did looked at bacteria on different substrate in the deep sea. And one of those was plastic. And what I found, along with many other researchers that have looked at this in different environments, is that we get a different type of community of bacteria and archaea on plastic than you would on wood or fabric or glass or metal, which is some of the other substrates that I looked at. This helps us really understand how disease transmission can be made. It can be just an increase of a particular type of bacteria, which happens to be a pathogen for a particular organism. But the other piece we need to look at is that plastics themselves move through the ocean. We call them a transboundary issue. Here in the UK, we could lose plastics out of one of the rivers, but it might not end up here. It might end up in the Caribbean, or it might end up in the Mediterranean. There are some amazing models of our surface ocean to figure out where they might end up, but we don't really know.

[00:16:43.390] - Dr. Lucy Woodall

As plastics move along, they're just not inert. Things live off them, right? So something that could be absolutely fine here around the UK, if it ends up in the Caribbean, might be problematic. Could be an invasive disease or a pathogen for something.

[00:16:58.390] - Clark

Oh, my goodness. I literally I would never have thought of that, of bacteria living on plastics moving across the entire ocean. Of course, we've seen some pretty catastrophic events happening with the introduction of a new species into a new environment.

[00:17:12.640] - Dr. Lucy Woodall

Then finally, you were talking about structural damage, what's happening there. I think this is mostly associated, I would say, with larger pieces of plastic or indeed the processes that get plastic into the environment. This can sometimes be some quite heavy things as well, but this gets washed down with the increasing storms and stormwater. This can land on our reefs or on any of our other coastal habitats and damage them as storm surge comes through. But we also have processes such as fishing. Fishing on Coral reefs can include plastic gear, and just the fact of having that gear on the reef can damage the reef itself.

[00:17:54.420] - Clark

So bearing in mind all of these consequences, you also mentioned that we should remember that coral reefs are facing a lot of other pressures outside of plastic or in addition to plastic. One concept that comes up a lot on the show also is that of compounding issues where one environmental stressor makes an organism or an ecosystem even more vulnerable to another. Do we see any ways in which plastic has an interplay with other stressors facing coral reefs? Yeah.

[00:18:20.790] - Dr. Lucy Woodall

I think it's really important to think about plastic and climate change as not separate identities. We wrote a paper a few years ago now, and there's been many follow-ups as well to show this into play. Across the planet at the moment, we've got a few crises. We've got plastic pollution, we've got reduction of biodiversity, We've got climate change. While they seem maybe so massive and so challenging to get your head around even just one of them, why would you put all three of them together? But in fact, that's what we have to do to think about solutions that are not siloed. Unless we think about all of these things together, then we're not going to come up with solutions. So when we think about stresses, we absolutely have to think about this climate change component that's related to plastics. I think what I would like the take home message to be that, yes, plastics are a challenge, climate change is a challenge, unsustainable fishing practices, and many other forms of pollution, unsustainable tourism is also a challenge to our coral reefs. But unless As we think about these things collectively and ensure that the actions we put into place are sustainable into the long term, then we're not going to get that long term change that we need for future generations to be able to prosper and even to survive.

[00:19:46.220] - Clark

Right. I think we've also tried to cover that intersection between climate change and plastic on the show. I'm wondering, though, is it still too early to tell how plastics are affecting coral reefs ability to perform their ecosystem functions? Are Are you seeing any evidence of that yet?

[00:20:02.840] - Dr. Lucy Woodall

I mean, there was an amazing global study that came out that was looking at large pieces of plastic and the prevalence of disease on coral reefs that had plastic or less plastic. And they were showing there was more disease. But as I said before, it's really about the mechanisms involved. We can hypothesize what those are, but also what we need to remember is there's not going to be one mechanism, right? Our biological communities are as complex as we are as human beings. It's not just one thing that's happening, it's multiple things happening.

[00:20:37.280] - Clark

The next question is, and I'm going to be going back to what we were mentioning at the beginning of why it's important to study the deeper reefs. The paper that I read that you published found something quite interesting that basically said that microplastic concentrations are... Okay, let me read this. Most studies see that microplastic concentrations decrease at lower depths so that we see more micro microplastics at the surface, but then deep sea reefs comparatively have higher concentrations than shallow reefs. My question is, why is that happening?

[00:21:10.260] - Dr. Lucy Woodall

Yeah, so great question. Let me start by clarifying a few things. Yeah, so lots of studies have gone through and they've taken water at the surface and down through the water column, and they said, as we go through the water column, then there's less microplastics. Now, the study that we showed was an accumulation of data that we'd collected and also acknowledging the amazing work that others have done as well. But it looked at large pieces of plastic that we could physically identify. And this was on the reefs themselves. So it was looking at plastic on reefs at different depths. We're comparing different things. We're looking at microplastics versus big bits of plastic, and we're looking at water column versus sea floor, but at different depths. While it's surprising, and you might think the shallower, the more plastic because that's nearer to humans, and let's face it, humans are where plastics come from. There could be a number of different reasons. Firstly, it could be that, in fact, some of those reefs are right up in the shallows because of the various stresses, things like bleaching and the dying back of some of these reefs have caused them to be less complex.

[00:22:21.990] - Dr. Lucy Woodall

They don't have the same structure as reefs that have been protected by slightly cooler waters in the depths. It could be a structure or piece. It could be that we're just not observing them in the shallows because there's many other things that are distracting us. We're only humans. It also could be that when we get down to a to depth, we're not getting resuspending of the plastics in surges or as the tidal cycle goes through, and actually they're sitting there and accumulating more. There could be lots of different reasons that we're seeing this. We could We're going to certainly report on what we've seen to date. I think it's really important for us to keep our minds open and say, actually, depth was a really important indicator of where we're likely to find more plastics, but actually for us to really understand and really ask questions you've asked me is why? Why is it at these particular depths? Is it something about the sites that we were looking at or is it something a little bit different? Now, we also looked at other key predictors of where we found this debris, not just plastic, but other human debris.

[00:23:31.460] - Dr. Lucy Woodall

This was things like closeness to human habitation, closeness to markets, and also closeness to maroon protected areas, areas that have some form of area and geographic protection. If there's a trading center nearby, especially if that's to do with fisheries, then you might expect more fisheries to be in the area. Again, those things make sense. The one that stumped us for a little while was the closeness to marine protected areas, right? The whole point of having a marine protected area, let's just remind ourselves what that means. Marine protected area has got lots of different definitions, but essentially it's a geographic area in the ocean where some specific activities have either been banned or they've been regulated in a certain way, okay, to protect that bit of the ocean. But then let's think about it. Why do we have marine protected areas? And that's because we know that providing geographic area protection to areas means that biodiversity increases, you get greater fish numbers and larger fish. Okay, what do fishers want? They want bigger fish, larger numbers of fish. So this is buffer zone, and we call it spillover effect, right? Fish don't know where the edges of marine protected areas are.

[00:24:52.980] - Dr. Lucy Woodall

So if you fish just that side of those, then maybe you'll get some of the benefits of these areas. And we think that's maybe what's happening, why we're seeing maybe larger amounts of plastic near to marine protected areas because of fishers using this spillover effect and trying to have greater fishing effort in these areas near the protected areas.

[00:25:16.010] - Clark

Sure. I wonder how you would even address that, because unless you make the whole ocean marine protected area, then there's always going to be an edge to the protected area. I wonder what you could do about that.

[00:25:29.120] - Dr. Lucy Woodall

It's a really good question. In fact, lots of people have thought about it, and these are things like buffer zones. You have your clear zonation of what's protected. Maybe it's no tape, maybe nobody can go in it in the center. Then you've got some other zones that maybe tourists can go into in boats. Then maybe you've got some areas where other activities can go on, maybe line fisheries, but no nets. Then you might have a boundary area around that. Then outside of that is the full area you can undertake any activities?

[00:26:02.870] - Clark

Well, this is leading me perfectly into the next two questions, which maybe I can ask together. You've worked on an article as well that was discussing the Global Plastics Treaty negotiations. The purpose of this article was to argue why this treaty must center ecosystems. I'm wondering if you have any reflections on that. Then the next question would be at the same time is if understanding how microplastics are impacting deep sea coral reefs specifically might influence the negotiations or policy outcomes as Our thought about really trying to center the discussions on the ecosystems takes us back to why do we care?

[00:26:39.490] - Dr. Lucy Woodall

Why do we care that there's plastic pollution? Why is there a global recognition that there needs to be a treaty about this particular product? We don't have a global treaty about glass or wood or anything else. It's about plastic itself. I think this is just an opportunity of being able to reflect and turn it on its head and say, actually, what are those things that need to be prevented to allow us to think about there to be a success with a plastics treaty? What we're trying to see in this treaty is something that acknowledges the consequences of plastic on humans, on human health, on human wellbeing, on human livelihoods, and on biological systems. Because in the end, if you don't have biological systems that are healthy, you cannot have human communities that are healthy and thriving.

[00:27:36.540] - Clark

Yeah, I like that idea of using ecosystems as a metric of success to see its effectiveness, because I guess that's the whole point. That's what we're after. Well, as we start to wrap up the episode, I want to ask you if there's anything that we missed today that you think we need to talk about in a discussion about plastics and coral reefs.

[00:27:55.640] - Dr. Lucy Woodall

No, I mean, I think we've covered such a huge range of topics in an area that is already so vast and there's so much amazing work going on across the globe with it. But this shouldn't be an issue that is just tackled in individuals' homes, in individual communities. It needs to be tackled by a global plastics treaty that is strong and robust and ensures that there are really clear guidelines about what we, as global citizens, want to see for our futures.

[00:28:28.430] - Clark

I think we can definitely agree on that. Well, then the last question I have is, where can listeners find you and follow your work?

[00:28:34.560] - Dr. Lucy Woodall

Yeah. So I've got websites up at the University of Exiton also with Necton, which is nectonnmission. Org.

[00:28:42.870] - Clark

All right. I will be sure to include links to all of that in the episode description so that listeners can find it easily. And this is the part where I say thank you so much for taking the time to come on the show today. Thank you for teaching us about coral reefs and most importantly, for your very important research in this space.

[00:28:57.010] - Dr. Lucy Woodall

Great. Well, thank you. It's been lovely chatting with you today.

[00:29:08.570] - Clark

You've been listening to Plastic Podcast. You can find more information about this week's guest and links to their work in the episode description. Cover art for the show was done by Laurel Wong, and the music you're listening to was done by Tadeo Kbejas. I am your host, Clark Morkaisi, and this episode was produced and engineered by me. If you found it interesting, send it to someone you know. Plastic Podcast is part of a larger network our sciencey podcast called Pineforest Media. You can find more information about us in the episode description as well, or on our website at pineforestpods. Com, or on Instagram and TikTok at pineforestmedia. We've got some exciting sciencey podcast coming out this year, and a five-star rating across platforms and a review on Apple Podcasts is one of the best things you can do to support science communication like this and make sure we reach more people, and it also helps the entire network to grow. All right, thank you to all of have made it this far, and we'll talk soon.