Webinar: Tracking Coral Health in the Caribbean Sea
May 12, 2022
Maggy Benson:
My name is Maggy Benson. Welcome to Smithsonian Science How. We have a great program today. We are going to be exploring how marine biologist, Leah Harper, tracks coral reef health in the Caribbean. Leah is joining us from the Smithsonian Environmental Research Center in the MarineGEO program. And we are feeling really lucky to have her with us today. So a little bit about today's program. We are going to be on a webinar, so you can't turn on your video and you can't turn on your microphone, but you can interact with us through the Q&A which all of you are doing right now. Welcome to some of our new friends who have joined us. And we will be taking some of those questions for Leah during the show.
We also have closed captions for today's program, which you can activate by clicking the CC button on your Zoom window and selecting show subtitles. And we also have ASL interpretation today. Thank you so much for doing that interpretation for us.
Today's program has a couple different sections. First, Leah's going to introduce us to herself, MarineGEO and coral reefs. And then we get to go on a virtual dive with her to encounter some of the species that she sees on a coral reef in the Caribbean. And then we're going to learn a little bit about how Leah measures the coral reef biodiversity, all the different animals that live on that reef, and how that helps track its health. At the very end of the program, we will take questions for Leah and we will take them throughout the program as well if they arise. So continue using that Q&A space and we will continue to monitor it. So without further ado, I want to invite Leah to the program to join us. Hi Leah.
Leah Harper:
Hi Maggy. Hi everybody. My name is Leah. I work for a program called MarineGEO, which stands for Marine Global Earth Observatories. And MarineGEO is a team of scientists from the Smithsonian and our network of global partners who are working together to monitor the world's nearshore ocean habitats with the long term goal of building diversity for resilient coasts. We try to understand how marine biodiversity can work to maintain functioning ocean ecosystems that benefit both animals and people with clean water, fisheries that provide food for people to eat, and foundation species like corals that resist environmental stress. Things like global warming and diseases. We answer these questions by diving into the ocean and counting plant and animal diversity in different places, how many there are, what they're doing and how all of those elements change over time. The ocean's huge and the questions are really broad so it takes a team of us from all around the world to get the job done.
Maggy Benson:
What an important mission. And I'm so happy that some of our friends get to learn directly from you today about it. Before we move on, I do want to give a shout out to a couple more of our friends who have joined. Thank you for joining us Miamisburg Middle School in Ohio. So happy to have you. Also Nicholas, Nathan and William from Schenectady, welcome. And Sophia and Adam from Virginia. All right. So we see here a couple of pictures of the MarineGEO network. These are some of the individuals that make this work happen, right Leah?
Leah Harper:
Yeah. On the left there's partners that are working in Canada and on the bottom right, a group in Hawaii. And I'm the group on the top right along with Maggy.
Maggy Benson:
All right. So you've mentioned that MarineGEO is dedicated to looking at different types of ecosystems that are coastal. So can you tell us a little bit more about what those ecosystems are?
Leah Harper:
Well, today I'm going to emphasize the ecosystems that we work with in the tropical Caribbean region. And so the background picture here is a picture of the Smithsonian Research Station at Carrie Bow Cay in Belize. It's the most magical research station that I've ever been to. It's a really wonderful place because it's surrounded by all of these different habitats. So offshore, there's the big coral reef, fore reef habitat and then inshore, there's a network of mangroves, which are tree islands that can live in the salt water, sea grass beds, and then smaller patch reefs too. And today we're going to really be focusing on the coral reef habitats because those are my favorite to study.
Maggy Benson:
So what is biodiversity? We've mentioned it a couple times already, but can you give us just a quick overview?
Leah Harper:
Biodiversity refers to the number and variety of species. And there's a lot of different ways to measure biodiversity. It can be as simple as the number of different named species in a habitat type, or it can be as broad as looking at things like the number of herbivores versus carnivores. So plant eaters versus meat eaters, which we call functional diversity. And MarineGEO is interested in all types of biodiversity.
Maggy Benson:
And so why is MarineGEO so focused on understanding all of that biodiversity?
Leah Harper:
That's a really good question. Because of all of the changes that have happened in the world over the past hundred years or so, and probably even before, scientists have realized that the earth is gradually losing species. And you guys have probably heard about extinctions, but animals are going extinct in some places faster than we can even discover them. And that's a big concern because biodiversity is really important to the health of ecosystems where each animal, each type of animal in each species plays its own role. And when we start to lose animals, we start to lose the function and the health of the ecosystem as a whole, and things start to collapse. So MarineGEO's really interested in monitoring how biodiversity changes across different places and across time too.
Maggy Benson:
This is a really important mission and a really big network of individuals to be able to do this really important work for really our global health. And so, Leah, what is it like in your position? You're a marine biologist with MarineGEO. You also work at the Smithsonian Environmental Research Center. What's a typical day of work look like for you?
Leah Harper:
Well, a typical day of work when I'm able to go out into the field would be a lot of scuba diving, which I love to do. And when we scuba dive for MarineGEO a lot of what we're doing is counting things. So we're looking for different animals, we're counting animals, and then we're entering the data and keeping track of all of the things that we've counted. So we count corals, we count fish, we count invertebrates, and then we keep all of that information organized and I spend a lot of time planning, organizing, and then after the fact analyzing data as well.
Maggy Benson:
What an amazing job if you like to be active and being able to be immersed in nature every day. Well, not quite every day because there is desk work too, isn't there?
Leah Harper:
There is. Especially lately, but we're about to get back out there.
Maggy Benson:
All right. Before we move on and really look at what a coral ecosystem is composed of, we want to do a quick poll, so you can participate with us today using the poll features. And we want to ask you why you think that studying these coral reefs and biodiversity is important. So you can vote on the poll that just popped up on your screen and tell us if you think it is to track coral and coral reef health, track invasive species. There's a lionfish there, which is invasive in the Caribbean. Discover new species or track change over time. We'll give you a moment to vote and then we'll share the results.
All right, well done everyone. We have just about everyone in. We'll give everybody about five more seconds. Five, four, three, two, one. All right. So very aligned with what we are talking about today, the most popular answer here is to track change over time. Leah, we also have a couple votes for tracking coral reef health and tracking invasive species and nobody voted for discover new species. So can you tell us a little bit about what you think?
Leah Harper:
I think that all of these answers are correct and all of them are important. Yeah. There's good reasons to focus on all of these things. I really am interested in tracking change over time and tracking coral and coral reef health, but there's an entire lab at the Smithsonian Environmental Research Center that focuses on invasive species and MarineGEO has actually discovered new species at different projects that we've worked on before.
Maggy Benson:
And that is also really important and really connected even to tracking coral reef health. All right. So we have a couple of really beautiful images here. Leah, today you're going to talk about constructing a coral reef and what's in that. So can you just show us a little bit of what we're seeing if we were to scuba dive on a coral reef like you do?
Leah Harper:
Sure. So when you go to a coral reef, the first thing that you notice is usually the corals. The stony corals, which are an animal. And they build the structure of the reef, which is really important because that attracts other animals that ... Well, it consolidates the bottom of the ocean. So there's a hard surface that the corals build and other organisms are able to live on that surface. So things like sponges, sea fans, and sea plumes. And then all of that structure attracts invertebrates that live in amongst the habitat that's created. And then that attracts fish to come in and eat the invertebrates and eat the algae that live there. And you start to build this entire food web where you dive in and see the corals and all of the fish and other animals. And it's very exciting.
Maggy Benson:
And so that is what we're going to be learning a little bit more today. And here's a picture of you doing some work on a reef. What exactly are you doing in this photo?
Leah Harper:
Sorry, I need to click this box down so that I can see what I'm doing. So in this photo, I'm taking pictures of the bottom. I'm swimming from one spot to the next to take pictures of the sea floor so that we can analyze the cover of different organisms. And cover just refers to how much space they're taking up relative to one another.
Maggy Benson:
That is very, very cool. It's a really cool picture too, to see all of the different kinds of corals and different kind of cover on that bottom. And so we have a couple more pictures of corals here, but I think we're going to take a quick break before we move on to take some questions. We have a question here from Sophia and Adam, which is asking how many fish are in a typical coral reef and what is your favorite fish?
Leah Harper:
Wow. How many fish? That's a good question. It depends on the size of the reef because some reefs are tiny little patches that you can swim laps around really easily. And some reefs are hundreds of miles long. And so reefs that are 100 miles long are going to have obviously a lot more fish than smaller reefs. So what we're really interested in as scientists is actually measuring the density of fishes. So how many fish we can find in a consistent amount of space. And that number can vary a whole lot. I'm still not really sure what a typical coral reef really would be. And my favorite fish is a really hard question because I think my favorite fish, I probably haven't seen yet because I still haven't seen a whale shark. And I also still haven't seen a mola mola, which is the fish that I probably most want to see. But I don't know if I can call it my favorite, because I haven't found one yet.
Maggy Benson:
All right, we have another fish question. Where did the lionfish come from and why is it invasive in the Caribbean?
Leah Harper:
Ah, good question. The lionfish are thought to come from the aquarium trade. So people keep them as pets in their household aquariums. They're originally from the Indo-Pacific. So the Indian and Pacific Oceans. The tropical region from there. And it's believed that either somebody released one or they somehow ended up in the Caribbean and because they don't have natural predators, they're able to really rapidly take over. And so they're considered invasive because they're not from the Caribbean and they're causing a problem.
Maggy Benson:
And we have another question here and then we'll move on. What is a Mola mola?
Leah Harper:
I wish I had a picture.
Maggy Benson:
I can pull one up right now.
Leah Harper:
Yeah. It's the ocean sunfish. They're huge and they're circular shaped. And they swim in a really weird way. They don't really have tails. Yeah. That's a Mola mola. I really want to see one. They're humongous. But they mostly live in the open ocean so it's very, very uncommon to see them on a coral reef.
Maggy Benson:
And their baby stage is a tiny little ... It looks like a spiky gumball. They are very, very cute. All right. And we'll take two more quick questions and then we'll move on. What is the biggest fish that you have seen?
Leah Harper:
The biggest fish that I have seen was a shark. I have a picture from this dive later, but I don't have a picture of this shark. I still don't even know what kind of shark it was. But I was diving with a bunch of coworkers before I worked at Smithsonian and they were on a boat and they had gone fishing and they were cleaning the fish and throwing the fish heads back in the water and it attracted this big shark that came up under me. It was probably eight feet long. So not that big for a shark, but the biggest one I've seen so far. It was very cool.
Maggy Benson:
Okay. Last question and then we'll move on. From Nathaniel. Nathaniel wants to know how many fish are in the Great Barrier Reef and I'm going to add on, have you ever dove the barrier reef? And this is the Great Barrier Reef in Australia.
Leah Harper:
Sadly, I haven't dove the Great Barrier Reef yet. I have not gone diving in the Pacific Ocean yet, but hopefully very soon. So I don't know how many fish are there, but we have partners from MarineGEO who have done a very good job of counting the fish there. So the data does exist if I wanted to find it.
Maggy Benson:
It's all part of this wonderful global network of scientists working and sharing information. All right. So Leah, you are going to lead us through. You gave us a little bit of an introduction about how a coral reef is structured. And you are going to talk a little bit more about that now. So here we see an image of a coral reef, but you have prepared a couple of graphics to show us exactly how a coral reef is built and show the great diversity of different kinds of species that are all part of this important ecosystem.
Leah Harper:
Yeah. So like I was sort of touching on briefly, the coral animal is unique and special because it can build a habitat and it can build a long lasting habitat that will stick around even after the animal dies, at least for a while, until it erodes. And that's because they are able to pull calcium carbonate out of the water and use it to build their skeleton, which is basically like big rocks. By doing this, they create what we call reefs. So that's hard substrate or hard bottom in a place that would otherwise probably be sandy. And that is the foundation for the entire habitat. And so we have our stony corals.
And because they are able to create this hard foundation, other soft bodied animals that live on the sea floor are able to live there too. And so that would be things like sponges and sea fans and sea plumes. And those are also animals. So if you ever go snorkeling and you see the sort of wavy purple things that look maybe like plants living on the bottom of the ocean, those are actually animals, which is really cool.
And so all of that structure attracts other animals because animals are attracted to safety and they like little nooks and crannies to hide in. And so the reef is full of tons of teeny tiny little invertebrates. So things like little crabs, little snails, and they live in and on the reef. And so here are our sea fans and our sea plumes. Inverts living all around. There's also algae that grows on the hard bottom. And so between the invertebrates and the algae, there's a buffet of food for fish because we have herbivorous fish that come to eat the algae and we have what we call invertivores so they're animals that eat invertebrates that come to eat the little critters, like the worms and the little sea stars that live on the reef. And that starts this foundation for a fish food web, where we get bigger and bigger fish that are all attracted to this area because it's pretty much where all the food is in the surrounding ocean. And so that is a general overview of why we see so many animals and so many different animals on a coral reef.
Maggy Benson:
Now we have a poll coming up in a moment, but we have a quick question about sponges. Somebody wants to know how squishy a sponge is.
Leah Harper:
It depends on the sponge. Some of them are like mush and some of them feel like a rock.
Maggy Benson:
And they're actually made of these little spicules called glass. So if you touch a sponge, it does not feel squishy at all. It actually hurts because that glass is actually penetrating and cutting your fingers.
Leah Harper:
Yeah. If you work with sponges a lot, the spicules get stuck in your fingers and then they tingle for days. It's not fun. I don't study sponges.
Maggy Benson:
All right. So thank you so much for showing us how all of these different plants and animals compose this really complex ecosystem. And I mean, that composition really brings us to one of the major areas of your study is really thinking about the biodiversity of those coral reef habitats. And so we prepared a poll for all of our viewers right now to think like Leah and think about which reef may attract the most biodiversity. So we just reviewed all the different biodiversity, all the different groups that create a reef system. But which one of these reefs do you think would attract the most?
Both the variety of animals and the abundance. How many of them there are. So we have three images there. We have reef A, reef B and reef C. So you can just make a hypothesis, a prediction and tell us what you think.
All right. You can also vote by the Q&A. We have a couple votes in there. All right. Well done everyone. And we'll give you about five more seconds. Five, four, three, two, one. All right. Well done. So we have votes for all three reefs. In the Q&A space we have a couple folks who have voted for reef C and also reef A. And in our poll, the winner is reef B. So Leah, tell us what you think.
Leah Harper:
Well, based on structure alone, which is one of the things that scientists believe is a big predictor of biodiversity on a reef within a given region. So that's to say, if we're talking about Belize, within Belize we expect that reefs that have more structure are probably going to attract a bigger variety of species. And so I like B because you can see all of the nooks and crannies. It's like a fish jungle gym with a ton of places to hide and a lot of different heights of corals. Some tall corals, some short corals. And you can see a lot of cracks and crevices that fish can dive into and hide and also eat because there's invertebrates hiding in there as well. A was also not a bad answer. C, the reef used to look like this, but unfortunately is pretty dead and has collapsed. And so there would still be fish there, but B would probably be my answer if I were guessing.
Maggy Benson:
All right, so well done scientists. You did a great job looking at these and making a prediction. We are going to learn in a moment about Leah, how you study these reefs and measure the biodiversity. But first we do have a couple of questions and I'm going to pull up the beautiful reef picture while we ask them. Okay. Sarah would like to know if you have ever found a new or rare species.
Leah Harper:
I have found a new species. I found a fish that was new to our MarineGEO data set, which I'll show you guys later. And so sometimes I find things that are uncommon, but no, I've never found a new species.
Maggy Benson:
Mrs. Bullock's third grade class has an important question. Why are coral reefs in danger and are all reefs in the world in danger?
Leah Harper:
Great question. There's a couple of different reasons why coral reefs are in danger. It's still a big topic of conversation and even debate among coral reef scientists which of the reasons are most important. But a huge reason is global warming because the sea temperature has been rising and corals have a very narrow range of temperatures that they like. So they can't live in cold water. Or most coral species can't live in cold water. But they also don't like it too hot. So they're some of the pickiest animals when it comes to the thermostat in their house. And so as the sea temperatures have been rising, what ends up happening is corals bleach and that is a symptom of stress. But the problem is when they bleach it causes them to become really, really weak. And a lot of them die after bleaching.
And that's known to be caused by temperature stress. From heat stress. And so that's happening on a global scale. And so in that sense, all coral reefs are in danger. But then there are also more local problems that can cause more reefs to be more in danger than others. And that would be things like overfishing. So especially places where they fished all the top predators out that can cause problems with the food chain that disrupts the ecosystem pretty badly and places where they take the herbivores. So the plant eating fish that eat the algae, when they're gone, they're not able to control the algae and then the algae can start growing over the corals and that causes problems. And there's a lot of other things that people do locally that stress out the reefs. Construction. There's a long, long, long list. But I would say that all coral reefs are in danger because of global warming and climate change.
Maggy Benson:
CJ made a good connection to the image that we're looking at and what you're telling us and wants to know if the tips of the corals on the image that's being showed, this reef B, are bleached.
Leah Harper:
That's a really good question. I don't know if I'm going to be able to answer it super precisely. But no, that's actually a normal color for this coral species. They grow from the tip. This coral species is called Acropora cervicornis. And the end of the branch is called the apical polyp, the last polyp on the branch. And it always looks white like that. I think it's because it hasn't acquired its symbionts yet. That's a fancy way of saying the little algae that live inside the coral animal and help give it its food. And that's what leaves if it bleaches. But all that is to say that's a normal color for this species.
Maggy Benson:
All right. Great connection and question. And we'll just take a couple more. What is the most common color of corals or is there a common color of coral?
Leah Harper:
That's an interesting question. Well, I haven't been to the Indo-Pacific yet. I've seen a lot of pictures. I see different colors over there. So just speaking about the Caribbean, brown is the most common color of coral. They come in a lot of different shades of brown, but some are green and some are purple. And my favorite thing is some corals have ... And I still don't know what causes this. This is something I'm very interested in. I don't really understand it, but sometimes they have a fluorescent coloring that makes them highlighter orange or really, really red or highlighter green. And it's usually when they're in low light. And I think it has something to do with helping them survive in low light conditions. And I know that some people have done some research on it, but I don't think it's super well understood. And it's really, really pretty when that happens.
Maggy Benson:
That brings up a good point, Leah, that a lot of what you're studying and what you're doing in your work is really documenting things for the first time in terms of what we know about different aspects like color and coral and the biodiversity and how all of these things are connected. So this is a great pathway for a future career for anybody out there today to be able to learn and really help these ecosystems.
Leah Harper:
There is a lot that we don't know still.
Maggy Benson:
All right, so we have a lot of great questions. We're going to keep them here and come back to them. So as questions arise, keep using the Q&A space and we will come back to them. But for now we are going to go diving with Leah. So Leah, remind us where we're going to go on a dive with you to see what you do and how you do it to measure the coral reef health to be able to track.
Leah Harper:
All right, we're going to go diving at one of my favorite places. My favorite places to work Carrie Bow Cay in Belize. So this is part of the world's second largest barrier reef. So not the Great Barrier Reef, but almost as cool. In my opinion, just as cool. And it runs from the coast of Mexico down to Honduras, but we're going to be in the Belize section and we're going to be diving on the fore reef and the patch reef.
Maggy Benson:
All right. So these areas over here, if you can see my mouse. All right. So what is the process? So you go diving, but you can't just jump in the water and see what you see, right? There is a process to this.
Leah Harper:
Yes. So the question that somebody asked about how many fish does the average reef have? Because we can't count all the fish on a reef. Nobody could do that. You can't even count all the fish on a very small patch reef. It's just too hard. So one of the most important things that we do in science is we standardize the area that we're looking at so that we're actually getting the fish density or the number in a specific area. And so we use a survey method where we swim in a designated area and we try to take a consistent amount of time and we count all the fish that are in that area. And any fish that are outside of that area, don't get counted. And those are the rules of the survey.
Maggy Benson:
And so that's a really basic component of all scientific studies, correct? Where you have to do something in the same exact way so that you can compare over time and over locations so that you could compare the Belize reef to the Great Barrier Reef right?
Leah Harper:
Absolutely. And that's one of MarineGEO's main missions is to try to connect people around the world to make sure that we're doing these things all in the same way. Because even something as simple as counting fish can become really hard to compare if you use different methods.
Maggy Benson:
Okay. So Leah, you are working underwater. What kind of tools do you have to use to be able to do this?
Leah Harper:
Well, a big one is scuba gear and an air tank. If we work in really, really, really shallow water, it's maybe possible to do some of these surveys on snorkel, but it's honestly a lot harder. It's really nice to be able to be down right off the bottom and see. We can see much better. So we pretty much do all of our fish counts on scuba gear and definitely all the coral counts. And then we use a transect tape, which is just a measuring tape. A really big measuring tape. And that helps us mark the area that we're going to survey and then pencil and paper to collect data. They make paper that you can write on underwater. That's just a regular pencil. And we go through a lot of that. And then underwater cameras are important too because whenever we see something that we want to remember or see something that we don't know what it is, it's really important to get a picture so that we can go back and check later.
Maggy Benson:
Awesome. So not a lot of fancy equipment other than, I mean the camera in the scuba gear, but you're not using submarines or any high tech thing here. But what kind of skills, what kind of process do you have once you gather all your materials, know where you're going to go and dive in?
Leah Harper:
Sure. Well gathering the materials and organizing beforehand is half the battle because once you're underwater, if you've forgotten something, it becomes a big problem. And then when we get to our site and jump in, we find our location. We try to survey the same exact spots year after year. Not everybody does it that way, but it allows you to make a direct comparison. So it's just another way to standardize our data collection. So we find our exact spot that we've marked with cinder blocks or something like that and then we stretch out the measuring tape and we swim along the tape and write down what fish we see and tally how many there are. And we record that and bring it home and enter the data. And that's how we assemble our fish database.
Maggy Benson:
And what kind of things do you see?
Leah Harper:
In Belize, I see a pretty big variety of fish and invertebrates.
Maggy Benson:
Can you walk us through some of these critters that you encounter along a dive?
Leah Harper:
Yes. So the-
Maggy Benson:
Oh, here. Let's start here. So actually we have a video, sorry.
Leah Harper:
That's okay.
Maggy Benson:
So this is a video of you, right? Diving in.
Leah Harper:
Yep. I'm the one on the left. I don't know if that was ... We're going to follow our nurse shark guide. There's a lot of nurse sharks in Belize. They are very friendly with divers, because they're used to getting fed. Sometimes people actually feed them lionfish, which is maybe not the smartest thing to do but the result is that they've become very interested in approaching divers as you can see here. So a lot of our surveys in Belize were surrounded by hungry nurse sharks trying to get a meal.
Maggy Benson:
And here's some of them now. Are those the biggest fish that you encounter? We had a couple questions about the biggest fish you see.
Leah Harper:
In Belize, yes. Except for my last trip to Belize, right before the pandemic started, I saw a manta ray, which is way bigger than a nurse shark and that was really cool.
Maggy Benson:
That's amazing.
Leah Harper:
I didn't get a good picture of it, unfortunately.
Maggy Benson:
All right. So you are diving that transect and you are encountering everything. So we saw that video of seeing the nurse shark, but do you count everything you see down there? Does it have to be along the line?
Leah Harper:
It has to be along the line to count in our main data. So the protocol that we use, we actually are able to write down other animals that we see if it's on that dive, but it doesn't get included in the main data. It's more just a species list of things that we know we've seen at that site. But you can't use it for any sort of mathematical analysis because it's not going to be in the standard area that we count. So it has to be in our transect, we call it.
Maggy Benson:
Okay. So you said that you write everything down and right now you're going to show us some of the species that you encounter along a dive. And while you're down there, you are writing down what you see and collecting that data. But Mrs. Bullock's third grade class would like to hear again how that works underwater.
Leah Harper:
Yeah. So we have special paper. It's very expensive paper. I really hate when I waste it. We have special paper that is ... It doesn't disintegrate underwater and you can just write on it with the normal pencil and it works great. I like to keep my pencil tied to a clipboard. So I have my paper on a clipboard and then I tie my pencil so that I can't lose it because pencils, they mostly don't float. They mostly sink. But it's very easy to lose things underwater if you're not holding onto everything and that's pretty much it.
Maggy Benson:
So who are we looking at now?
Leah Harper:
This is a sand diver. These are pretty common fish, but they're a little bit hard to spot because they're very, very camouflaged.
Maggy Benson:
Right. Should we move on to the next one?
Leah Harper:
Yeah.
Maggy Benson:
All right. So we're going to go through. I'm going to follow Leah's lead.
Leah Harper:
This is a sharksucker, which is similar to a remora. And these things are really fun. They travel with usually whatever the biggest fish in the area is. So in Belize, a lot of times that's the nurse sharks. Sometimes it's big sea turtles and sometimes it's us. Sometimes they're swimming around by themselves and they see us and they suck onto your leg. We have wet suits on so you can't really feel it. It doesn't hurt. But they'll suck onto your leg and follow you around for your dive.
Maggy Benson:
And they're big fish too. Because they can come up and approach you and sometimes they can startle you because they're so big and they get so close.
Leah Harper:
This is a black grouper. These are very uncommon to see in Belize. I actually saw this one while I was, I think, doing a coral survey. So I didn't get to count it towards my fish data, which is sad because we don't count these guys very often. And their reason that they're uncommon is they are delicious and popular to eat. So there aren't many left, unfortunately. And it's a very big fish too. This is a sharpnose puffer. They're one of my favorite fish to take pictures of because they're very, very cute. They're very small. Just maybe two inches long. And one year, it was 2017, I will never forget it, there was some sort of population boom of sharpnose puffers, which means that all of a sudden they were everywhere and I don't know why. They were everywhere you could possibly look. And we see it in our MarineGEO fish data where the graph for that species is flat, flat, flat, and then just this colossal spike off the charts and then it collapsed the next year. So that was really wild.
Maggy Benson:
Oh, that is so cool.
Leah Harper:
These are both the same species (threespot damselfish). And I just want to highlight that this is one of my biggest challenges for identifying fish when I'm doing surveys, because on the left is the juvenile and on the right is the adult and they look so different. So we have to learn not only all the species, but all the juvenile and adult colorations and appearances. And that's tricky for me.
Maggy Benson:
We talked a little bit about the materials you get together and the process of swimming this, but can you tell us about what kind of preparation has to happen for you to do this kind? Because you know all of these fish, but then adding in knowing the difference between the baby fish and the adult fish, that's really challenging. So what general skills have helped you do these kinds of tasks?
Leah Harper:
Good question. I took a training before I ever did these surveys. And actually in a couple of weeks, I'm going to travel to another place in the Caribbean to take training to become a trainer. So I'll be able to train our partners in doing these surveys. So there's a really formal class that we take to make sure that we're doing the surveys correctly. And then the other thing that I did is I studied. So just like studying for a test. I used online flashcards before my trip and I'll probably be doing that before my next trip, because it's been a little while. And I study the fish and make sure that I know them before jumping in the water.
Maggy Benson:
And you can't bring that book underwater can you?
Leah Harper:
Nope.
Maggy Benson:
All right. Oh, this one's really cute too.
Leah Harper:
This is a smooth trunkfish. I don't really have a good story about this fish other than this is one of my favorite pictures that I've taken in a while. I just like them. They're cute.
This is a blenny. And blenny is a broad term for a type of fish that lives in little cracks and crevices in the reef. They live in little holes and they can be very, very small. So the one on the right is one of the smallest blennies I've ever spotted. It's maybe about just twice as big as my pencil point, if you guys can see that there. His little eyes poking out. One of my, in my opinion, talents is spotting very tiny things. When I was in graduate school, I worked on projects looking for baby corals, which can be very, very tiny. And so I've had a lot of practice spotting tiny animals and organisms.
Maggy Benson:
It's so tiny. I don't know if you could see why mouse there, but it's at the end of this pencil tip. So if you're holding a pencil, take a look at that. And this fish is just a little bit bigger than that. So cool. Okay. I'm going to go to the next fish.
Leah Harper:
So this is a goby, which is about the same size as the blenny. Maybe a little bigger than that last blenny. They're also small fish that would count in our surveys. And this is an example of why taking pictures is so important because some of these less common species, we can't expect to know everything that we could ever possibly see, right? You learn the common things. So there might be a hundred common things that you know off the top of your head and then sometimes you see things that you're not sure. And so this guy I took a picture of and I learned afterwards when I was trying to figure out which type of goby it was that it was the first one that we'd recorded at Carrie Bow. And the only difference between this one and the common one that looks similar is that the stripes on its body connect in the front in a point. And in the common one, it just has stripes that don't connect. And that's the only difference, which I never would've known if I hadn't gotten a good picture of its nose.
Maggy Benson:
Wow. That's incredible. I just tried to put an arrow on that tiny little space. And we did have a question. Where is this goby and the last blenny hiding?
Leah Harper:
The last blenny was kind of just on the like hard bottom. It's surrounded by what we call turf, which is just a matrix of really small, fine algae and sand. And so they live on either dead corals, sometimes on live corals, but these ones are on just dead coral or the bottom. I honestly don't remember exactly where they were. And then this goby is inside a fire coral colony.
Maggy Benson:
Okay. Ooh.
Leah Harper:
Oh, these are scalloped hammerhead sharks. These are from actually the same dive that I was talking about earlier where my friends were cleaning their fish and drawing in all the sharks. But these guys were there the whole time. It was a school of them. It's not a very good picture, but this is one of my favorite dives that I ever went on because there was this school of scalloped hammerhead sharks that was just circling the entire time. And it's pretty rare to see schooling hammerheads so that was really exciting. This was actually in Florida.
Maggy Benson:
That's amazing.
Leah Harper:
It was cool. This is a hogfish. This picture's also from Florida actually. So I cheated a little bit. This one wasn't in Belize. I actually don't see very many hogfish in Belize. And the reason we don't see many hogfish in some places is they are also delicious, like black groupers. They're really super tasty. And so this guy's hanging out in a coral nursery, which is a place that people build to grow corals. And he's hiding out there because it's a big structure and he's got some protection.
Maggy Benson:
We did have a question about the color of the water. In this picture it's very turquoise, in this picture it's purple. Can you tell us a little bit about taking pictures underwater and why it's purple or blue?
Leah Harper:
Yeah. You'll probably notice that the vast majority of pictures that I've shared here are pretty bright blue. And that usually means that I've taken a close up picture in a place with good visibility. That's when I get my best pictures. And visibility first to how far we can see in the water. So basically you need really good visibility to get a good picture of the seascape, otherwise you just can't see very far and it doesn't look beautiful. So the picture of those hammerheads, it wasn't good visibility. That's actually edited so you could see them better. It was pretty cloudy. And so in cloudy water you can't really get a good picture of the entire seascape. And the color that you see can indicate whether you're going to have ... The color of the water can indicate whether it's going to be clear or not. That's something we actually notice when we're diving, because even in Belize, sometimes the visibility isn't the best. And you can kind of tell if the water from the surface is really, really blue, you know it's going to be a good visibility day, but if it's a little bit green, it's not usually good.
Maggy Benson:
Okay. Good question. Let's see who else we have here.
Leah Harper:
This is a toadfish. And on its head, you can see a Peterson shrimp, which is a type of cleaner shrimp. And so they are helping each other out because the Peterson shrimp is cleaning little critters that live on the toadfish. And in return, he's getting a free meal. So you'll see these cleaner shrimps cleaning, all different kinds of fish.
Maggy Benson:
If it was me diving, I don't know if I would notice that toadfish unless I saw that shrimp on top of its head.
Leah Harper:
Right.
Maggy Benson:
Very camouflaged.
Leah Harper:
And they live under crevices and stuff. So you have to know where to look. But one thing that helps is that they make a really loud noise. I think that's why they're called toadfish. They make a loud croaking noise. And so that can give away their location sometimes.
Maggy Benson:
All right. We just have a couple more here.
Leah Harper:
This is a reef squid, which are one of my favorite things to see. They are really cool because they have these special cells on their skin that change colors and they can use that to send messages to one another. I don't know what the messages are, what they mean. I don't know what this one's saying. But it has a cool grid pattern.
Maggy Benson:
It's beautiful
Leah Harper:
Saying something. This is a hermit crab. I talked a lot about counting fish, but at MarineGEO, we're also really interested in invertebrates. So things like crabs, worms, sea stars. And hermit crabs are something that we count in our invertebrate surveys. And they are, I think, the hardest animal to identify, because first of all, if I saw this shell upside down, I'd be like, "Oh, that's a conch." But then when I pick it up, there's a hermit crab. So totally different species. Not even the same phylum. So we really need to be careful when we count any kind of shell on these surveys. And then the other thing about hermit crabs is that they usually don't really want you to see them and so they will retract into the shell. And then it's really hard to ID something that won't come out. So they're very tricky, but they're also fun. And this is underwater to be clear because there are land hermit crabs and there are marine hermit crabs, and they're not the same. There's a lot of different species of hermit crabs.
Maggy Benson:
I know, Leah, you prepared a tricky challenge for us. And this really goes with Mrs. Bullock's third grade class' question about what happens when different fish swim in and out of your research study area. But you prepared this to give us a demonstration of what it's like to be able to count a school of fish. So what do you want us to do here?
Leah Harper:
All right. I want you guys to watch the school of fish swim by and try to figure out how many fish you can count.
Maggy Benson:
Okay. All right. So we see the school there. And tell us in the Q&A space, how many fish you would record on your data sheet if you were Leah and these fish swam through. Now, this is a real challenge, Leah, that you have in your work, isn't it?
Leah Harper:
Absolutely. This is one of the trickiest parts. And after you guys answer, I can tell you what I was taught in the class that I took about trying to estimate the number of fish in a school.
Maggy Benson:
All right. So we'll give folks another minute or two to be able to use the Q&A space this time. Not the poll, the Q&A. To tell us how many fish you think is in this school. And while we give everybody another moment, Leah, what kind of fish are these?
Leah Harper:
These are surgeon fish. They're really important herbivores in the Caribbean. They eat a lot of algae. Which you see them darting down to the reef to pick algae off.
Maggy Benson:
Okay, I'm going to review some of these responses. So 300 to 400, tens of thousands, 350, 1000, 200, 952, 191, 300, 266, too many to count, over 200 and under 300. So what do you think about these estimations?
Leah Harper:
There are a lot of reasonable answers in there. I did this earlier and it's harder in a video than it is in real life, I will say. But I got about 250. And it's an estimate. So anywhere from probably 200 to 400 is reasonable. And the way that I was taught to do this with a school is it's impossible to count all of them. So what you want to try to do is count 10 and figure out how much space 10 fish takes up, and then visualize how many blocks of 10 fish are in the school. And that helps you get an estimate.
Maggy Benson:
Very cool. So we only have about five minutes left. So I want to just do ... We have one more thing and then we're going to get to all of these questions. And I just want to remind everyone that when you leave today's program, when you close Zoom and your browser window, a survey will automatically pop up and we would love for you to respond to that survey. And we also have a poll that will pop up in a moment or two to rate today's program. But for now, Leah, I just want to quickly cover, because we did mention that ... I'm going to move this forward. You are going to Belize in just a couple of days to be able to measure coral health. And we have a couple questions in the Q&A about diseased corals. So can you introduce us a little bit to the work that you're going to be doing to be able to track the health of these corals?
Leah Harper:
Yes. So in the Caribbean, corals have been experiencing their own pandemic. We've called it Stony Coral Tissue Loss Disease. And it started in Florida. It's been spreading throughout the Caribbean. It wasn't in Belize the last time I was there. And so what we did is we used these little yellow tags to mark a bunch of corals, and we took samples from the corals. And the plan is to check on them over time and see which corals get disease and if we can identify any characteristics of corals that are more likely to get disease or more likely to not get disease. And so we tagged a couple different species and of different levels of susceptibility or their likelihood of getting sick from the disease. And we're going to go back next week and check on all of these colonies and take new samples and see whether they're healthy or not. And unfortunately, the disease that we're concerned about has arrived in Belize. So a friend of mine sent me this video from Belize just about maybe six weeks ago. And this is a coral. It's sick with Stony Coral Tissue Loss Disease. It progresses pretty fast. So there's a very good chance that unfortunately this colony will be dead when I get there next week.
So we're excited to check on our corals and hopefully they're doing okay. And if not, we're going to at least use them for science to try to figure out what are some of the characteristics of corals that get sick versus corals that survive.
Maggy Benson:
Leah, this is really important work. Thank you so much for telling us all about how MarineGEO and you count the biodiversity on a coral reef, and then use that information to be able to track its health such as looking to the coral loss and looking at the Caribbean, but all over the world.
We are going to launch our final poll right now to rate this program. But I am going to serve up a bunch of questions for you. Now I'm going to stop this share, but I'll pull it back up if there's anything you want to reference. So if anyone can stick around for a couple minutes and Leah, if you're okay just staying a couple minutes, we'll get through more of these questions. Have any predators ever attacked you while you were diving?
Leah Harper:
Nothing that you guys would probably think of as a predator. The most aggressive fish in the Caribbean are damsel fish, which are this big. And they bite us a lot because they're protecting their territories. And so they've attacked me a lot, but they don't really hurt.
Maggy Benson:
And they're kind of cute.
Leah Harper:
They're pretty cute. Yeah.
Maggy Benson:
Are there any stingrays in the coral reef?
Leah Harper:
Yes. There are a lot of stingrays. In Belize we see a lot of stingrays.
Maggy Benson:
When you dive, do you ever see trash or dead animals?
Leah Harper:
Trash often. Depending on where, but yes. Although a lot of trash floats so more you see it on the boat. And dead animals, no. They pretty much get eaten right away. So in a place with a lot of animals, you're not likely to see anything dead. And if you do, it's pretty creepy and weird.
Maggy Benson:
How long do corals live and can corals die?
Leah Harper:
They can definitely die. A lot of them are dying now from both temperature stress and from diseases. And how long they can live depends on the species. Some are shorter lived species, some are longer lived species, but longer lived species can live hundreds of years. So there are some very, very old corals out there.
Maggy Benson:
So thinking about the health of a reef, one of our friends has heard about fishing with cyanide. Does that happen in the Caribbean? And if you can explain what that is real quick.
Leah Harper:
Oh, sure. That's a technique where fisher people go and just sort of ... It's indiscriminate. So it doesn't select which fish to kill. It just kills all of them with poison and then they go down and throw the fish in a bag that they want, and I guess leave the rest. And it is not common in the Caribbean. That's more common in some parts of the Indo-Pacific.
Maggy Benson:
We saw a sick coral with that Stony Coral Tissue Loss Disease. One of our classes wants to know, can you help sick coral?
Leah Harper:
There are a lot of people who are trying to help sick coral. There's a lot of groups that are working. It's been an evolving ... Because it's a new disease, it's been an evolving strategy. So people are constantly learning new ways to do this. But one of the first approaches was to use antibiotics. So probably the same antibiotics that you guys would get for an ear infection, people have gone down and put them on the corals where they're sick. We call it a lesion where it's white and the tissue's sloughing off. One of the problems with antibiotics is that can lead to antibiotic resistant bacteria. And so that's a really big concern putting antibiotics into natural ecosystems because it could lead to unintended consequences and bigger problems down the road. So a newer approach that scientists are taking is to actually use probiotics, which I don't know if you've heard of probiotics, but you've probably eaten them. They're in yogurt, they're in sauerkraut, which is maybe not the most popular food but I love it. And they're also thought to help corals. It's really promising. We're going to take some samples from healthy corals in Belize to send to a scientist who works on probiotics so that he can start to try to culture probiotics specific to Belize that we might be able to use to help the corals there.
Maggy Benson:
So a related question. Can a dead reef recover by itself or perhaps with probiotic treatment or some kind of treatment> and if so, do scientists know how long it would take?
Leah Harper:
That's a really good question. It's a hard one to answer. The way that coral reefs recover ... Well, it would take a long time. When these big colonies lose their tissue, it takes a long time to grow back. And the other unfortunate thing about some of these big coral colonies, like the one in this picture and others that really form the foundation of the reef, is that they're both slow growing and as far as we can tell, they don't make babies very often. And so what ends up happening is reefs can recover in that new corals will come take the place of the old corals. But a lot of times they won't be the same species. They'll be hardier species, species that can survive in worse conditions. And that is what we're starting to see a lot of in the Caribbean. Even the soft corals, like the sea fans and sea plumes, they can tend to colonize and come into an area that's lost all the corals a lot faster than these big, massive, long lived corals. So recovery isn't quite recovery. It's more replacement, unfortunately.
Maggy Benson:
And one final question from Nathaniel. What is the coral population and Belize? What does that look like? That cover or that population? Variety.
Leah Harper:
So at our sites around Carrie Bow, the coral cover, we measure in percent. And so the percent is like, if you're looking down at the sea floor, what percent of the bottom is covered by different types of animals. Coral covers only around 12%. So only around 12% of the bottom of a coral reef is actually covered by coral right now. Which sounds bad and it's quite bad actually, but it's still better than a lot of places in the Caribbean, which is alarming. And there's about 60 species that we see there. So it's not super diverse, but it is a pretty ... There's a bunch of different looking coral. So it's a little bit hard to answer exactly what the population looks like, because it depends on where you go and whether you're deep or shallow. But about 12% of the bottom is covered in coral on average.
Maggy Benson:
Wonderful. Leah, thank you so much for answering all these great questions and thank you especially to all of our friends watching, who asked such great questions and joined us today to learn about your work in the coral reefs and coral reefs in Belize. This has been really fun. We are going to sign off, but before we do, Leah, do you have any advice for our students if they want to pursue a career like yours?
Leah Harper:
Yeah, absolutely. There are a lot of skills that you wouldn't really think of if you're thinking of being a scuba diving marine biologist, but that are really important. A big one is being organized. And I didn't learn how to be organized until I was already a marine biologist. I would suggest probably starting working on that earlier. But it is a huge help because you can't be forgetting things when you're going to work underwater, because there's no way to get it other than having to surface and start over. And then the other skills that you can practice are identifying animals. Because you don't need to identify fish to learn the skills that it takes to be able to group different animals together and notice patterns. So you can practice learning to identify birds. You can learn to identify insects. You can learn to ID plants that are around you. And those kinds of things help tune you into your environment and help you learn how to ask the questions that will train your brain to do the type of work that I do now.
Maggy Benson:
You don't have to go scuba diving in Belize to be able to start practicing now. You can start in your own backyard.
Leah Harper:
Absolutely.
Maggy Benson:
Thank you, Leah. It's been really wonderful to have you here today and thanks again to all of our friends who tuned in to watch. We will be back on Smithsonian Science How on the 26th. So May 26th. We will be joined by Dr. Earyn McGee to find that lizard. So a little bit of a different content type, but it'll be a lot of fun. And today, if you can fill out the poll or the survey that comes up in your browser window after you leave Zoom, that would be excellent so that we can continue giving you programs that you want and need in your classrooms. So thanks again Leah for joining us. Thanks to all the educators behind the scenes who made this program happen. We appreciate all of you. See you later.
