SPEAKER_00 0:57

Good morning everyone and welcome to Work on the Reef. I'm your host, diver, and marine conservationist Tanya Murphy. And joining me, as always, is Cand Aquarium's marine educator and fish whisperer, Brett Goodbeck.

SPEAKER_02 1:09

Good morning, Tanya. Morning everyone. Hope everyone's had a great week.

SPEAKER_00 1:12

Brett, you know when there's a toddler and you have to cut up their food into tiny pieces to make it easier for them to eat.

SPEAKER_02 1:18

I'm very familiar with that. Yes.

SPEAKER_00 1:20

Well, orcas have been observed doing a similar thing, but with a technique that's a lot more explosive. A bit more aggressive. A researcher in the Gulf of California has filmed an orca headbutting a dead sunfish so hard it exploded into a cloud of scraps. I saw that. Yeah, it's gone a bit viral. That makes it easier for the juveniles to find pieces to eat. According to the ABC News article, when a killer whale butches a fish, it needs to use its head, preferably as a ram and at high speed. But they also use their brains because it's it was a very calculated speed. Yeah, well the way that they coordinated it. And uh for anyone who's unfamiliar, the sunfish is one of the world's largest fish, but they aren't very agile. They're shaped like a huge disc, up to three meters in length, and more like a UFO.

SPEAKER_03 2:12

Yeah.

SPEAKER_00 2:12

Hence their name, it's gonna sunfish. And they tend to just float around slowly, making them easy prey for orcas who like to boot them with their snouts and push them around. But they're also dense, rubbery, and hard to tear apart, so the orcas have figured out a way to fragment them, and it's not the first time this behaviour has been observed. In the viral video, a female orca holds the already dead sunfish in position like a target, then a male charges towards it and she lets go of it just to see mate's impact. It's like a perfectly tired oral path. Let me come out. Well, the sunfish was already deceased. Um but you know, orcas are a bit known for playing with their food. Now, orcas are known to be able to reach more than 40 kilometers per hour in short bursts, and the impact of the orcas now hitting the sunfish creates a loud crunching sound and an explosion of fish bits which are hoovered up by the docraft. So it's equally messy as feeding a toddler, really.

SPEAKER_02 3:13

Oh, absolutely.

SPEAKER_00 3:13

So it ends up everywhere.

SPEAKER_02 3:15

No, I reckon my boys are messier than that.

SPEAKER_00 3:18

Isn't a natural world just fascinating?

SPEAKER_02 3:20

Yeah. It's a whole planet down there. It's awesome. Not for the sunfish. I'd just like to point out.

SPEAKER_00 3:27

Well, they've been on the planet for millions of years, I think. So they've they've gone okay, they stunfish.

SPEAKER_02 3:31

Yeah, they're really funny because they can't swim backwards either. So it'll be like the batfish that people see on the roof, you know, the round you put your hand up and they swim towards you, they just sit there because they don't know how to go backwards until you move your hand. Stuck forever. Yeah.

SPEAKER_00 3:45

Uh well, I think the sunfish has survived because they have a huge amount of spawn. They just procreate. Good on them. Yeah. Good for them. Don't actually know that much more about, but I would like to get a sunfish expert some other time.

SPEAKER_02 4:01

So all our listeners around the world, if you're a sunfish expert, get onto us and we'll get you on the show. Give us a call. Yep, absolutely.

SPEAKER_00 4:07

Now let's dive into today's topic. Brett, I want you to imagine that you've been handed a rather enormous job. You've got the ability to do things that could help boost the reef's resilience. Propagating corals, restoring damaged habitat, culling the coral-eating crown of thorn stars. But there's a capture. You can't do it everywhere. The Grey Barrier Reef is absolutely enormous. It covers an area bigger than New Zealand, and it's made up of more than 3,000 individual reefs. And with ocean warming projected to get significantly worse over the coming decades, we simply don't have unlimited money, time or people to restore every reef. So, Brett, if you had to choose which reefs would you protect, where would you go?

SPEAKER_02 4:51

Don't you dare do that to me. It's like asking which one's your favourite child.

SPEAKER_00 4:55

I know, except there's 3,000 of the 3,000. And they're all intricately reliant upon each other.

SPEAKER_02 5:00

Look, so I don't offend the other 2,999 reefs. I do have one in mind, but I'm not telling you which one it is. Anyone that knows me will probably know which one I've picked.

SPEAKER_00 5:14

I know you've passed it to the coral C, but you've got to go somewhere first, don't you? So it's a tough decision.

SPEAKER_02 5:19

It is.

SPEAKER_00 5:20

And unfortunately, when it comes to reef restoration, we really do have to make choices about where our efforts can have the greatest impact. And that's where today's research comes in. Our guest has identified 112 key reefs that could be particularly important targets for restoration. Reefs where investing our limited resources could potentially give us the biggest bang for our buck. So, what makes these key reefs special? How do you actually work out which reefs are the best candidates for restoration? And if we can't restore the entire Great Barrier Reef, could strategically protecting and restoring these key reefs help preserve the reef as a whole? And perhaps most importantly, can we actually use restoration to buy ourselves some more time while we tackle the much bigger problem of climate change? Here to help us answer some of those questions is Professor Peter Mumby, head of the Marine Spatial Ecology Lab at the University of Queensland. Good morning, Professor Mumby, and welcome to Word on the Reef.

SPEAKER_02 6:22

Morning, Brett. Good morning, Professor. Thank you so much for joining us.

SPEAKER_00 6:25

It's great to have you on the show. Now, before we dive into the topic of priority reefs, can you tell us a bit about yourself and your background?

SPEAKER_01 6:34

Sure. So I grew up in the UK. I became fascinated by the Great Bay Reef. I used to have the Reader's Digest book on the reef. But of course I'd never been to a reef. I'd only been down to the local shore and messed about in rock pools. But I had this dream that one day I would get to see something that fantastic. And I I did a degree in marine biology at the University of Liverpool. And during that time I went on an expedition to Belize in the Caribbean. This was my first visit to a reef, and it really blew me away. And I and I knew that this was going to be something that I would wish to make the rest of my life work, if possible.

SPEAKER_00 7:11

You got hooked in on your first dive, just like the rest of us. Yeah, there's a common theme.

SPEAKER_01 7:16

Yeah, and I've been fascinated by coral reefs ever since. And I worked for many years in the Caribbean and then moved to Australia 16 years ago. For a bunch of reasons, but one of which, from a brief perspective, is that you know the Great Barry Reef has about ten times as many species as you find in the Atlantic. And it's so much more complicated and it really provides a huge challenge scientifically to try to understand bits of it.

SPEAKER_00 7:43

So that's been great. Ten times more species in the Atlantic. So that includes the Caribbean. Pretty amazing. We're so lucky here, aren't we?

SPEAKER_02 7:50

Oh yeah. Yep.

SPEAKER_00 7:52

So we're really intrigued to talk about the priority reefs. But first, while we're on the topic of the Caribbean, I want to talk about parrot fish because parrot fish are awesome. And we haven't really talked about them on our show yet.

SPEAKER_02 8:03

No, we haven't.

SPEAKER_00 8:04

And they play a really important role in reef health. And Professor Mumby, you helped achieve protection for them in the Caribbean. But for any listeners who aren't familiar, can you please describe the parrot fish?

SPEAKER_01 8:15

With pleasure. So parrot fish are particularly brilliantly coloured fish. They are typically about twenty to thirty centimetres long. They have a a beak, very much like a parrot beak. And like parrots, they swim just using their pectoral as sort of side fins and just sort of push themselves forward.

SPEAKER_00 8:34

Yeah, so it's like they're flapping their wings, whereas a lot of other fish swim by swishing their tail from side to side. So yeah. Easily recognizable as a parrot-like fish.

SPEAKER_01 8:43

Yes, and so they lead an interesting life. So they'll often start out as male or female, but then uh as they get older, uh they'll have a territory. And there'll typically be a male who will dominate that territory. And that territory may be, you know, twenty meters by twenty meters in size, something like that. And he'll dominate and have a harem of maybe six females in his territory, and they'll spend most of the day feeding. So they're just uh scraping the bottom and trying to extract food from just inside the surface of the reef. Um they're feeding on some of the sort of bacteria and algae that's associated with that surface of the reef. So they're scraping the surface, keeping it clean. And then depending on what time the tide starts to go outwards, as soon as the tide starts to move out, they'll all come together and and spawn together for about 15 minutes and then go back to eating again. Um so they lead a very simple life. But their action of scraping the surface of the reef for food is really important at preventing seaweeds getting established. Because those seaweeds start off as tiny little spores that will just settle in what is known as the algal turf. And you can almost imagine that algal turf that's covering the dead coral, just like the turf you would have in a beautifully manicured lawn. You know, it's very, very short, whole range of algal species, but in there are the seeds, if you like, of some of the bigger seaweeds, uh much like we have, you know, weeds in our garden. And so the feeding of the powerfish, the constant scraping of that substrate, prevents those weeds getting started and you it keeps this kind of manicured lawn, I like to think of it, on the surface of the reef. And and that's important.

SPEAKER_00 10:37

It's like having sheep or using guinea pigs, putting your guinea pigs on the lawn to mow it for you.

SPEAKER_02 10:43

Remember seeing the the mass schools of the bumphead parrot fish coming towards you on the reef? The big the big monstrous ones.

SPEAKER_00 10:48

Yeah, well they've got a different style altogether, I think. Yeah, because you can hear them grinding away at the coral and Yeah, well, for any listeners who haven't, next time you go snorkeling, put your ears slightly below the water when you're snorkeling, and you'll hear the scratching sounds, especially if there's any parrot fish nearby. Yeah.

SPEAKER_01 11:04

That's sure. So, you know, most of these parrot fish are not feeding on the coral, they're feeding on the substrate. The bumped parrotfish is an exception. It does like to beat on coral, but so they'll be scraping the substrate, and that prevents these series getting established. That if they get established, they then can sort of foul the young corals that are trying to grow. So they compete and smother the young corals. And so sometimes the corals will survive that but they'll stop growing, and sometimes they get overwhelmed by that algal overgrowth. And so keeping the reef free of weeds helps coral recovery. And in places where this is exceptionally important, particularly in the Caribbean, because reefs in the Caribbean have a proclivity for the seaweeds to bloom. They bloom really easily. If you add a bit of nutrients, but certainly if you reduce the herbivores that are controlling, so these are the parrot fish, the grazers that are preventing them from getting established, if you fish too many of those parrotfish, the seaweeds take advantage of that immediately. And so there's a strong relationship between the amount of seaweed on those reefs and the ability of young corals to grow and recover.

SPEAKER_00 12:18

So parrot fish are some of our reef heroes. They're out there helping to control the weeds. Amazing creatures.

SPEAKER_02 12:24

And making nice fresh sand for everybody.

SPEAKER_00 12:26

Yeah, well, that's another byproduct of them scraping the reef, is they end up swallowing a whole bunch of fragments of limestone. And so if you're ever snorkeling out there and you see a parrotfish do a poop, and out comes a whole pile of sandy snow. Yeah, so I want everyone to think about that. Next time you're lying on a nice white sandy beach, a lot of the sand on the beach may have been produced by animals like the parrot fish crunching up the limestone in the ocean and pooping it out as nice clean white sand. So what an amazing service.

SPEAKER_02 13:01

Run your hands through the fish poo. Yeah. Just be one with the ocean people.

SPEAKER_01 13:08

There's a lot to love about parrotfishes. Oh, yeah. Well, they're absolutely good. And they play this role, and you know, and uh I mean I remember spending one summer just following them around leaves to get an idea how far, how big their home ranges are and how they reproduce and so on. And you get to know them sometimes a little bit too well. I I I got to the point where I could see when the male was beginning to start flirting, just a slight change in his behaviour. And I thought, I think I'm getting to know these fish a bit too well.

SPEAKER_00 13:39

Well, you could predict the tides by it then, couldn't you? You could, yeah. That's why we know traditional indigenous cultures are so good at reading the elements because they've observed animals for so long, they can read those kinds of signs. But anyone can learn to read those signs if you spend enough time just quietly observing the animal behaviour, I suppose. So uh yeah, tell us about the work in Belize and Bonaire with protecting the parrot fish that you did, Professor Mumby.

SPEAKER_01 14:05

Well, interestingly, when I first started working in Belize, if you'd asked the fishers, do you catch parrot fish? They would just laugh at you and say, No, no, we don't do that. This is what the Honduran fishermen do.

SPEAKER_00 14:17

Oh, they're blaming everyone else.

SPEAKER_01 14:19

They blame everyone. Well, but there was an element of truth to that, because in Honduras they would catch parrot fish, dry them and eat them during Lent. But in Belize they had a really healthy fishery, and so they were mostly catching and eating, you know, grouper, snapper, lobster, conch all the more valuable and desirable species. And that was in the early nineties. By 2004, parrotfish had become the most widely caught group of species in the country.

SPEAKER_00 14:45

Because they fished out all the others.

SPEAKER_01 14:47

They fished everything out. Or at least, you know, reduced the populations quite dramatically. And so I remember getting asked by one of the fisheries cooperatives that represent the fishermen to give a talk about the reef. And I talked about, you know, a lot of different things about reefs, I didn't talk about fishing, but I talked about the role that parrots play and how the ecosystem works and you know, and the fishermen at the end said, Well, so if the parrotfish are helping to keep the reef healthy for the fish that we really care about, snappers, the groupers and things, and keep all those hiding places that they need, why aren't the parrotfish protected? And so they talked about it among themselves and eventually took a vote, which was pretty much unanimous, that they wanted to take a recommendation to the fisheries department that there should be some protection.

SPEAKER_00 15:35

Yeah, the fishing industry themselves paying the price. Yeah, the fishing industry themselves took that step. Isn't that wonderful? Yeah, that's great, isn't it?

SPEAKER_01 15:43

Yeah, it was really it was I mean, I almost could scarcely believe it, but it was quite remarkable. And and so eventually that did lead to a ban on the exploitation of parrot fishing Belize. That came into effect in 2009. And what was interesting is that I've been monitoring reefs there for twenty years, and you can see over the next ten years a sort of recovery that the reef got worse and worse up until about that point. And then it began to show more stronger signs of resilience as those pirate fish recovered. Wow. Um and you know, so it was really I mean, I went through a fairly depressing phase in the middle where the reef was looking very different to how I first got to know it. And then it began to uh become more and more like what I remembered. And and so it was it was a a rare good news story on coral reefs.

SPEAKER_00 16:32

Wow, and and the fishermen benefit as well, because when there's healthier coral, the uh better fish that they actually wanted were rebounding.

SPEAKER_02 16:40

Isn't that refreshing? Like there's the people can see the bigger picture.

SPEAKER_00 16:44

Yeah. Sustainability, it benefits everyone that utilizes those resources. I love that story, and it just goes to illustrate the massive difference that is made by the presence of the parrot fish. They're one of the reef heroes. Yep. Not only really beautiful to see on a coral reef, so next time you're snorkeling, say thanks to a parrotfish. Yeah, do we need to add places like Bonaire and Belize to our bucket list, Professor Mumby? What are they like?

SPEAKER_01 17:10

Well Belize is a beautiful place to go. I mean it's fabulous because you've got the rainforest and you can sort of go into the rainforest and then you travel thirty, forty kilometers and you're at the coast and you've got the second largest barrier reef in the world. So Belize definitely and Bonaire, which is just north of Venezuela, is really special because it's so far south that it doesn't get hurricanes, for example. And the reefs are certainly among the most resilient of the entire Caribbean. And they do have I mean they've protected parrotfish for many years. And you can see that the parrot fish are really unafraid of people. It's quite remarkable. I mean it's a bit like being at Here and Island here where the fish don't consider people a threat whatsoever. And the reefs in Bon Air are spectacular, and the way that you explore Bonaire is that you just rent a truck, drive along the coast, and just stop wherever you like and jump in and dive or snorkel. It's really easy.

SPEAKER_00 18:03

Wow.

SPEAKER_01 18:04

And you'll certainly see some of the best that the Caribbean has to offer there.

SPEAKER_00 18:08

Yeah. I mean we we know, as you said before, that uh the Caribbean in general has a tenth of the biodiversity of the Great Valerie Reef, and then we've been hearing that large parts of the Caribbean are sort of functionally dead, really, from the severity of bleaching and climate change that has been experienced in the Caribbean. But it's good to hear that there are some parts that are relatively resilient.

SPEAKER_03 18:29

Yeah. Certainly.

SPEAKER_00 18:31

Yeah. How protected are parrot fish on the Great Barry Reef? Are they protected?

SPEAKER_01 18:42

Well, no. Uh they're not. And this this is an issue that goes backwards and forwards. And I think the dilemma is that the conversation goes something like this. Well, parrot fish aren't heavily threatened at the moment at all. There are some Spearhoes that will shoot parrot fish. Generally it's the ones that aren't very good that bother shooting parrot fish. Because they're so tame. You wouldn't bother. You'd be focused on something more challenging. So there isn't a huge threat, which usually means that's a very good time to try and take some action to protect them because no there won't be much opposition. But then because there isn't much threat, it's not a high priority. And so it's a it's a tricky one because you think well it's a sort of many would argue, well, why not just do it? Because you don't know how things are going to change in future. And certainly in much of the world, parrot fish may have at some point been relatively lightly exploited, but much of the world they're pretty heavily exploited. And and certainly, you know, it is possible in in many parts of the world to harvest parrot fish to an extent. You know, I work a lot in Palau in Micronesia and the biggest fisheries there on the reefs are herbivorous fishes, parrot fish and some of the surgeon fish. But they do so in a sustainable way, and the reefs aren't suffering as a consequence of that. But then there are other places where the fishing has just gone out of control and the reefs have suffered significantly as a result of that. So Yeah, it seems like a no-brainer we should be a no-brainer, but it sort of never quite reaches a high enough grade.

SPEAKER_02 20:14

Yeah.

SPEAKER_00 20:15

Something to think about. So let's talk about the priority reefs on the Great Barrier Reef. Professor Mumbee, why do we need to identify priority reefs for protection when, of course, we'd like to protect the whole Great Barrier Reef?

SPEAKER_01 20:28

Yeah. Yeah, of course. And it I mean that everyone would love to be able to protect everything. I mean, really the the idea was, you know, some reefs play a more important ecological role than others. And that sort of variability across the reef is pretty important at helping people prioritize where they might want to do the management, whether that's triangle and starfish control, whether it's part of the zoning plan that exists and so forth. And we were wanting to understand how the whole system is connected to itself. It's almost like imagining the sort of the circulatory system that we have, you know, understanding how everything flows within the system. And the way that we do that is we use the oceanographic models that have been developed uh mostly by the CSRO, for example, so they can model the coastal and ocean currents at a resolution of around about one kilometer. And then what people do is they simulate the release of coral larvae, they simulate spawning events on all of those reefs. And they track virtual larvae in those currents to figure out where they go. And so from that you can say, well, okay, this reef, if it released, let's say, a thousand points, how many of them reach the next reef downstream? Maybe ten percent of them reach the reef downstream, and maybe all the rest of them are lost. So you use this method to figure out how connected all of these reefs are to one another. So it's a big network. And then to prioritize where are the most important reefs, that means looking at the network to find the hubs, the ones that are really important at connecting to multiple other reefs and in a fairly predictable way. And then, of course, some of the you might have a reef that is connected to, let's say, ten other reefs downstream. So that's really important. And if some of those ten reefs downstream are also connected to many other reefs, you're starting to build a kind of domino effect, this cascade of connections that start to follow. And so we undertook that process for the first time in 2017, and what that showed is that pretty much if you just took around about About a hundred or so reefs, they could connect to nearly two thousand reefs. So if you pick the right reefs, there's a massive opportunity to achieve some scale. So that was really interesting because it it tells us that you don't have to do everything everywhere anyway. There is natural connectivity in the system that you could try to take advantage of.

SPEAKER_02 23:00

I I find this fascinating because I watched the YouTube video and we've had a look at this and had a chat about this before we came on air today. And for my position at work at the aquarium and teaching people about coral and how we're protecting the reef every day, learning about this other way of looking at it is a whole new refreshing idea for me. It's great.

SPEAKER_00 23:20

Professor Mumby, we watched one of your presentations on YouTube and and saw the images of the areas that were key sources of coral larvae. And for any listeners who aren't familiar, every November and December around the full moon, corals release eggs and sperm into the water, and these will fertilize and then they'll drift until they land on a nearby area, maybe onto another reef, and that's how they then grow from a baby into a new coral. And so that's why Professor Mumby was talking about trying to identify which reefs are passing on the most spawn, which are, you know, not just getting washed away into the wilderness to be wasted, but which are actually catching those ocean currents and then reseeding lots of other reefs. And so then theoretically we only need to focus our attention on the source reef at the top of that current and then produce more babies. Yeah, they will then restore the other reefs that are downstream of them. Is that sort of what you're saying, Professor Mumby?

SPEAKER_01 24:20

That's that's the logic, sure. It means that you can focus efforts in a relatively small number of locations and at least get some downstream benefit. So, you know, if you are doing some kind of management on one reef, it's likely that that will benefit at least some other reefs downstream. And this becomes increasingly important as if you look at the reefs of you know the last 20 years or so, in fact it's probably the case that most reefs are self-sustaining. That there's so much coral that enough of those larvae that are released that get kind of trapped around the island are probably most of the baby corals are actually coming from the reef that they were launched in. Because a lot of it is actually retained, and maybe about a quarter of it or so can be retained where those corals are reproducing. And that's fine if you've got quite healthy coral populations. But when we see reefs being hit very hard by these heat waves and the coral bleaching that can cause masses of mortality on a reef, then it slightly changes the equation because now it's less likely that that reef will be able to provide enough larvae to sustain itself, and that the larvae, the new corals, are more likely to have to come from somewhere else that escaped the worst of the bleaching. So this is sort of morphed into a very targeted activity now. And so what we do is if you look across the entire GBR, we divide it up into different regions, many smaller regions, and within each region the question is given that some of those reefs have been damaged, whether it's by bleaching, cyclones, clanothorn starfish, but some of the reefs still look pretty good. Where are the reefs that still look pretty good that are strongly connected to places that have been damaged? Because that's where protecting those reefs in good shape could help sustain the recovery of the other reefs around them. And that is a very targeted way of prioritizing where to intervene to maximize the recovery potential of the system. And this is really what's happening in the COTS control program and has done for the last few years. The challenge has always been how do you know the state of of as many reefs as possible? Because to do that analysis, you ideally need to know how healthy those reefs are, which ones are down, which ones are in good shape. And we don't monitor enough reefs to do that. We monitor about 90 reefs.

SPEAKER_00 26:50

Yeah, because the Great Barry Reef is so huge. Usually it's very hard to send scientists out to all of them. It's a lot of resources, it's a lot of eyes in the water.

SPEAKER_01 26:59

So that's where the idea of Great Reef Census came in. This was something that could be done by citizens. It doesn't have to be done by scientists. And that was the genesis of the project led by Citizens of the Reef of Great Reef Census that aimed to have people and various tourism boats going out there to do those surveys and feed that information into the system.

SPEAKER_00 27:24

Yeah, and for any listeners who may recall, we did an episode about the Citizens of the Reef and the Great Reef Census project back last year in season two. So go back and check it out. Have a listen. If you haven't already, but for anyone who's not familiar, it's anyone with a GoPro camera can jump in the water, send the photos in, and then they get crunched by the computer and they and then for anyone who's ever wondered what all that data gets used for, I think it's got various uses, but some of it gets looked at by you, doesn't it, Professor Mumby?

SPEAKER_01 27:56

Yeah, well it you know the text really come on, and so now what happens is those images are first processed by AI, of course, and that gets rid of all the kind of rubbish parts of the photo that might be in the background that you can't see it's too dark or it's missing a bit of reef. And then it starts to go through and identify where the table corals are, the branching corals, the big mound-shaped corals. And then those pictures are sent all over the world to people who are looking at these photographs on their phones, and currently I think there's people in 80 countries worldwide doing this just for fun. And they go through and they help identify what things are and say, no, the AI got this pitch slightly wrong, this is in fact noble coral, not what it thought it was. And it's also been done very widely in schools in Australia, and so there's been a terrific interest in people engaging with this, and by the time we've gone through the AI and through people who have complementary things they can see, AI is very good at some things, people are better at other things. You end up with images that are actually reasonably accurate. The analysis that gives you a pretty good estimate of how much coral there is, and we've tested that. And so that then, every single year, informs the selection of sites for the crown of thorn starfish control. Because one of the criteria used in selecting reefs for cot's control is the ecological importance of a reef. And so one of the major criteria there is is it a reef that is currently in a position that the corals there are valuable because they are providing this sort of replenishment surface where it's needed. And if that reef is also at risk of crown-thorn starfish outbreaks, well, that's a good reason to prioritize surveillance and culling. So that's been a really important way that the reef authority and tourism operators are trying to protect parts of the reef strategically, and part of that is being driven by data from citizens.

SPEAKER_00 29:56

Amazing. Back in 2017, when you first did this study, you used a few metrics to identify which are the key reefs to protect. And I understand it's sort of changed a bit since then with other factors. But looking at one of the maps from your YouTube presentation, we can see these black dots along the map of the reef which show which reefs are the key sources of coral larvae. And it's really heavily concentrated on the southern reef between Mackay and Gladstone. Yeah. Pretty heavy around Cooktown and north to the ribbons. There's this sort of big empty spot around Townsville that we found that really interesting. Is there something to learn from that? Yeah.

SPEAKER_01 30:43

Yeah. I mean, so that analysis was kind of looking at the sort of Fortune 500 of the top potential reef hubs across the entirety of the GBR. And they are patchy as you describe in terms of where they're distributed. But within each area, there are places that might not be in the sort of top 100, but they're still within that region reefs that are relatively important. And so, although we produce that figure to illustrate where the most important reefs are in terms of the number of connections and strengths of connection, and most of them are on those outer areas of the reef because the flow coming from the coral sea across the reef in towards the land then carries those larvae sort of inwards towards the land. So many of these sources are sort of quite a long way out. But operationally we look at it for every part of the reef. And so we look in every region and say, within this region, which reefs are the most important at driving recovery there? And sure, some areas there's easier to find really good sources of larvae than in in other areas, but every region of the reef has some places that are more important than others. And that's really the main goal is to find the places in each region that people can focus some of their efforts on.

SPEAKER_00 32:01

Yeah, okay. And so there's other factors that we probably need to consider, like the value of certain reefs to traditional owners and the tourism industry. Is that also a part of it?

SPEAKER_01 32:13

That's certainly part of the decision-making process undertaken by the reef authority in terms of where activities are targeted. And of course, increasingly, you know, that people are using more survey data in the management of sea country, particularly thinking, for example, the census methodologies are being used more and more. But the criteria we're looking at are purely ecological. Where are the reefs that have this function? And then you combine that, well, we don't, this is what the reef authority will do, you combine that with information on, well, what's the logistics? Can you even get to those reefs? You know, are they economically important? Are they socially important? And a whole bunch of other considerations. I mean, are they at risk of crown of thorn starfish outbreaks? And so it's a selection process that considers a wide range of criteria, but certainly being able to distill some of those ecological functions is really useful because I mean we really benefit from you know all this marine science that is available for the Great Barrier Reef. And putting that to use to help make some practical decisions about where to target interventions is great.

SPEAKER_00 33:20

Yeah, so uh after you identified that sort of Fortune 500 reefs, which are the key sources of coral lava, you then overlaid which reefs have the least thermal stress. So they're more likely to be healthy, which looking at this map, it looks like the southern reef again between Glasgow and Mackay. It's a part of the Great Barry Reef where it's more than 200 kilometres offshore, so it's very distant from runoff. It's close to the edge of the continental shelf. And according to this map that you showed in your presentation, that southern outer reef is the least exposed to thermal stress. And then you looked at the outbreaks of crown of thorns, coral eating staff and again it seems there's like a heavy patch of cotz exposure in the very far southern reef, but then there's an area off the coast of Mackay on the very outer reef which is identified as having very low cot exposure, and that seems to coincide with a lot of those super spreader reefs. And then when you overlaid all of those, you narrowed it down to 112. The map that we're looking at seems to be that most of those 112 reefs are again they're all in the south between Mackay and Gladstone. And I know you've emphasized that we need to look at every region, but just in that initial study, just purely of those 112 reefs that met all of those criteria, why do you think that they were all in that outer southern reef?

SPEAKER_01 34:44

It's a couple of reasons. One is that there's you know strong flow from the outside reefs coming in towards land. So that the ability to be a source and connect to many other reefs is really strong there because there are many reefs in that sort of middle area that can be reached from the outer GBR. So a great place for these strong connections. But the other thing is that's an area where there are some thermal refugia. For example, in the swains, there's an element of upwelling that prevents the reefs in some of those areas getting particularly hot. There are, of course, some parts of the swains that do get really hot. But there are areas in that part of the reef, a bit further north, in the hard line reefs, as there's some real thermal refugia there too. So these are places that it doesn't mean they'll never get hot enough to bleach, but generally speaking, they warm up significantly less than the average reef. And equally there are some places that get super hot during bleaching events. And there are some other refugia in the north as well. So when you start overlaying where the level of bleaching stress tends to be lower, and you overlay that with where the strong connections lie, and if you start considering things like chronicle and starfish, which is actually very dynamic, I mean at that time we were running these analyses, you know, we didn't have the benefit of all of the cost control work that's been done more recently, so we now have vast amounts of data on where starfish are and um and where they're being controlled, so we have much clearer information on that. So, yeah, it's a combination of those things. But certainly finding places where you've got this coincidence between thermal refugia and strong connections is an important combination of criteria. But they're not the only criteria that are important.

SPEAKER_00 36:34

How do we know those conditions which make those reefs ideal for protection aren't going to change in future? Because won't ocean currents and cots distribution change as the climate warms, and then will the priority reefs be in a different place?

SPEAKER_01 36:47

Yeah, well certainly cots are dynamic and so they're changing all the time. But there are some reefs that are persistently get COTS outbreaks more than others, and that's again partly due to the connectivity of the COTS themselves. They're doing the same thing as the corals there and spawning and moving from reef to reef. But with the temperature, that's a really good question because we know where they are at the moment because you know we have satellite sea temperature information going back to 1985, and you can look at all of those heat waves that we've experienced. And in every case, there are places that are generally cooler than the rest of the reef, relatively speaking. So the precedent historically is that some of these areas are predictably less exposed to these heat wave events. It doesn't mean that they never get it, but you know, it means that the majority of heat waves will affect them less. Now we have done some climate modelling and downscaling of what this might look like in future. Um this is with some colleagues in the UK. And so when we take the climate models and you scale so you simulate the oceanography, you do see some differences of opinion from one climate model to another. They sort of don't all agree on where the refugia will be in future. But there are places that they do agree on. And so those are the areas that we also consider to be quite important because there seems to be pretty good likelihood that they will be refugia in the future. The one sort of caveat in all this, and you mentioned it, is but what if the currents change? And that's something that no one has a really good handle on yet. There are some sort of preliminary estimates, but most of the projections going forward have not considered how you know changes in the East Australia current might drive changes in in these flows. So that's in the sort of to-do list. But certainly I think that it's often about what's the best available science we have right now. There are places that I think can be identified quite reliably as being these relative refugia.

SPEAKER_00 38:52

What do you believe we should be doing to protect these key priority reefs?

SPEAKER_01 38:57

Well, I think we need to look at what can be done to protect these networks and keep these networks working. So there'll be certain locations that really hold that reef system together. And part of the story is with the Crownathon staff is control. It will be looking to see do we have adequate protection on some of these critical reefs that in the long term are really important are holding everything together. And if there isn't enough protection on those reefs, and let's face it, the Great Bearer is extremely well protected in terms of the zoning plan, then maybe some measures to add some additional protection in a small number of locations might be warranted. I'm certainly not advocating that anyone goes through a rezoning of the Great Barrefs. That would be far too painful. And unless there's a very strong scientific case, I don't think there's rationale to do that. But maybe patching it in a few locations might be something that would be worth considering. And I think with the role of restoration, right now restoration is still being done primarily by tourism operators and it's still relatively small scale. And, you know, at this point, it's unclear how much of a role restoration could play in helping to maintain critical reefs into the future. I think we are developing, or we as in the science community have developed some pretty good methods for doing reef restoration. They can probably be applied at some critical reefs in future. And I think that the importance of that is likely to grow as more reefs are suffering stress. So I think there needs to be a sort of comensure increase in understanding the role and optimizing what restoration can do, given that it has to be, again, targeted very carefully in the same way as cost control needs to be targeted. It's certainly not a method that can be applied, you know, across large areas of reef. But if it's applied carefully in the right locations, it could play a role in helping to keep things moving.

SPEAKER_00 40:53

It wouldn't be a lot to redesign the zoning of the reef, which is you know very effective. But you're saying patching it as in, okay, maybe some of these really priority reefs, we could put a little no fishing bonus zone.

SPEAKER_01 41:06

Yeah. Yeah, yeah. I mean I think I think if you know, as long as there's a compelling argument for it that can build a social license, that you know, this isn't about trying to impact on people's recreational livelihoods, but there might be some areas that are really exceptionally important where reducing all possible stresses on that reef has value. And so I think a process like that, if it was done very carefully, you know, done in consultation, of course, with people, might be worth considering in certain locations.

SPEAKER_00 41:38

So we know that the biggest threat facing the Great Barrow Reef is climate change, and ultimately the long-term solution is to cut our carbon emissions, so tackling local stresses, reducing fishing and doing reef restoration on those priority reefs. How much of a difference can that make? I mean, will it be enough to save the reef from escalating climate change?

SPEAKER_01 41:58

And and I I believe it is important. And you know, one of the things that my team does is we've developed the models that are used to predict the future of the Great Bear Reef to the end of the century. And we spent years developing that in integrating science. And when we project the future based on our current emissions trajectory, which isn't great, it tells us that the reef will become heavily degraded in certainly the less second half of the century. But it isn't going to be dead. There are going to be areas where the corals are still not too bad, but the vast majority of reefs will have much less coral than we see today. But there will still be coral in the system. And the other thing those analyses tell us is that the things that drive healthier reefs, even in the year 2090, are things that we can deal with. Those reefs that have more connectivity, they do better. The reefs that are slightly in refugia, they do better. So even then, under all of that stress that's projected for the later part of the century, the things that we can do in terms of local management will have benefit. The reef will still respond to those things even under that level of stress. So if anything, the mandate for managing the reef and managing its resilience is stronger than ever because we have to know where we can apply pressure and interventions where the reef is going to respond positively to that. And it can.

SPEAKER_00 43:29

Yeah, so hopefully it's going to buy us a little bit of time while we get our emissions under control. It's not a replacement for climate action, but it's something that we need to do as well. That's another big step.

SPEAKER_02 43:40

Absolutely. Yep. Yes.

SPEAKER_00 43:41

All right. Well, we are down to our last three minutes, but I feel like we've covered most of the important things. Is there any last message you want to get across that we haven't already talked about? Professor Mumby?

SPEAKER_01 43:53

Well, no, I mean obviously the people listening, I think, probably have a real love of the reef, which is terrific. And I always encourage people to go out there and take a look. And if they can't get out there as often as they would like, then you know, participate in something like Great Reef senseless so that you're you can spend your time either in the water or out of the water contributing to making better decisions. It's a great way of engaging with the problems and you know, and it's it's having a direct benefit. So yeah, I think that the importance of having people's enthusiasm and support for undertaking more conservation and improving the conservation of the reef is really important.

SPEAKER_00 44:32

Yeah, our reef is struggling, but we can protect it. That's right if we all we're gonna need everyone. So everyone listening, get involved. And what sort of reef we have in 20 years or 50 years from now, it all depends on us, doesn't it?

SPEAKER_01 44:45

It totally does. And and this is something that the managers can't do it all, the scientists can't do it all. We all need to be involved, and there's an absolutely a role for citizens to help. That's really important.

SPEAKER_02 44:56

And that and that's one of our biggest messages on this show, isn't it, Tanya?

SPEAKER_00 44:59

Yep.

SPEAKER_02 44:59

Right? Everybody can get involved, the citizens are everywhere.

SPEAKER_00 45:02

Yeah, and it's today has been a really great example to demonstrate how some of that citizen science data from, for example, the Reef centers has all gone towards many things, including Professor Mumby's research, which might help us identify real solutions for keeping the Reef functional into the future. So it's been absolutely wonderful learning more about that. And uh sadly that's all we have time for today. So, Professor Peter Mumbee, head of the Marine Space Ecology Lab at the University of Queensland. Thanks for all your amazing work and thanks for joining us on Word on the Reef today.

SPEAKER_02 45:37

Thank you so much for the first time.

SPEAKER_00 45:44

Thanks for joining us on Word on the Reef.