In our second episode, we focus on the threatened species of manatees. Manatees are among the most beloved creatures that call the Indian River Lagoon home—but these graceful sea cows have recently been threatened with a concerning spike in deaths.
The IRL Council sits down with Dr. Martine de Wit from the Florida Fish and Wildlife Conservation Commission to discuss the importance of manatees to lagoon ecology and examine the cause behind this heartbreaking phenomenon.
To learn more about the manatee and the efforts being made to preserve their populations, visit the Florida Fish and Wildlife Conservation Commission’s website today.
To learn more about the IRL Council and our lagoon home, visit OneLagoon.org.
Share and Connect
[Audio transcription via YouTube]
- Dan Kolodny, Chief Operating Officer for the Indian River Lagoon National Estuary Program
- Dr. Martine de Wit, Florida Fish and Wildlife Conservation Commission
- Duane De Freese
Duane De Freese: Hi. I’m Duane De Freese, executive director of the IRL Council and the Indian River Lagoon National Estuary Program. Welcome to our One Lagoon, One Voice Podcast.
Each week myself or one of my staff members will host leaders in the community, scientists along the lagoon, people who know a lot about the system, to talk about some of the problems and most importantly some of the solutions to solve the Indian River Lagoon’s health and make sure it’s great for future generations.
If you enjoy hearing us talk about the lagoon, like and subscribe to this podcast. And be sure to follow us at One Lagoon on Facebook, Twitter, Instagram and TikTok. So let’s get the show started and let’s talk a little lagoon.
Dan Kolodny: Hello and welcome to One Lagoon, One Voice. I’m Dan Kolodny, Chief Operating Officer for the Indian River Lagoon National Estuary Program and I’ll be the host for today’s podcast.
So today we’re here to talk about one of the most iconic and beloved members of the IRL community—manatees. These aquatic mammals are known for their docile nature and graceful manner which have earned them the nickname “gentle giants”. The West Indian Manatee, which is our local species, was expanding its population in the early 2000’s and in 2017 was reclassified from endangered to threatened, but in recent years manatee populations in the Indian River Lagoon have faced increasing and complex threats from declines in water quality that have led to severe algae blooms that killed much of the lagoon seagrass—a major food source for these manatees.
So to help explain these issues and let us know what’s being done to support manatee populations in the IRL, we’ve invited our friend and colleague Dr. Martine De Wit from the Florida Fish and Wildlife Conservation Commission.
Martine, welcome to One Lagoon, One Voice.
Dr. Martine de Wit: Hi Dan. Thanks for having me.
Dan Kolodny: So can you give us a little introduction on yourself and how you got into being a marine mammal biologist?
Dr. Martine de Wit: Yeah, so I’m with the Florida Fish and Wildlife Conservation Commission and I’ve specialized myself in manatees, and I’ve been here for 17 years. I’m a veterinarian and I practiced as a clinician. First I was back home in the Netherlands and then I was really interested to do more with wild animals and that path took me to Florida. I’ve always been very much interested in manatees and so this opportunity came up and I was super lucky to get hired to help conserve them.
Dan Kolodny: So tell us a little bit about manatees, you know, what makes them so special and different?
Dr. Martine de Wit: Yeah, so manatees are unique in many ways but, you know, to start off you have to realize that manatees are native to Florida and if you look back at fossils of about like 50 million years ago manatees were already here. And those animals, if you look at the natural history museums where they have some of those specimens, they look very different from the manatees that we have now. They still have short legs and all, but about a million years ago you have the manatees like we still have here today.
Dan Kolodny: I’m glad you’ve mentioned that because I hear all the time when I’m out on the water boating that they’re not native and that’s quite the contrary so appreciate you telling us that.
Dr. Martine de Wit: Yeah, they’re certainly part of Florida and have been here longer than all of us.
Dan Kolodny: So what’s some of their range here in Florida? Do they spread elsewhere besides Florida?
Dr. Martine de Wit: Yeah, so Florida is the manatees’ home, but during the summer time some manatees will venture out, and they will travel along the coast. You can find manatees as far West as Texas, and then you have manatees that follow the Atlantic coastline that will end up in the Carolinas, or, you know, as far north as Virginia. The most northern one has even been [was] in Massachusetts.
Dan Kolodny: Wow, that’s incredible. They really do travel.
Dr. Martine de Wit: They do but that’s only during the summer time. So manatees are subtropical animals and they are susceptible to cold, so when water temperatures drop into the 60s manatees can develop a disease that is called cold stress disease, [or] cold stress syndrome—also known as Florida frostbite. That’s because they do not have much natural insulation and a very low metabolic rate. So to avoid getting sick they have to stay warm and they travel to warm water sites. That’s why they all have to return to Florida, and even manatees that stay in Florida year-round have to seek out those specific warm water sites.
Dan Kolodny: Can you describe what a warm water site is for our listeners?
Dr. Martine de Wit: There are several warm water sites that manatees in Florida will use. One of the most popular ones that the majority of manatees use are discharges from power plants. You have a very popular one in the lagoon: the FPNL Canaveral Power Plant.
Manatees will also use natural warm water springs on the West Coast. There is for example Crystal River, you have Blue Springs in the Saint John’s River, and then manatees can also use the thermal basins and examples of that in the lagoon are found in Satellite Beach.
Dan Kolodny: So, what specifically attracts, you know, manatees to the IRL? What makes the IRL so special as far as population-wise, because I know thousands of them sometimes hang out at that warm water power plant. So what makes it so special?
Dr. Martine de Wit: Yeah, so the lagoon, anywhere [in the] lagoon is popular with manatees for several reasons, and one of the main attractions is that warm water that they find there in the winter. And you can find, like you say, more than a thousand manatees sometimes using those warm water sites there. In peak time during the spring, about 70 percent of the Atlantic subpopulation can be all together in that site. So [it is] very popular during the winter. It provides a pretty good warm water habitat.
But even after winter and spring, if manatees do not have to stay warm at their warm water sites you will see manatees venturing out and moving north. Like I already mentioned some will move out of state. You’ll have manatees that stay in the IRL year round, and for example, you have animals coming from the south [that spend] winter in South Florida, and they will spend their summer in the Indian River Lagoon. That used to be because there was, you know, wonderful lush seagrass, so [it was] a perfect habitat to feed and just spend your summer time there.
Dan Kolodny: So I’m glad you touched on seagrass which is their main food source, right? And so you know I kind of mentioned a little bit in the beginning that they were delisted from endangered to threatened which suggests that they’re doing okay—but we’ve seen this massive die off in the last couple years. Can you kind of just go over what’s caused that?
Dr. Martine de Wit: Yeah, so you know, first of all, that delisting, the fact that manatees were considered threatened when they were assessed years ago doesn’t mean that they [are] doing okay. It was just less chance of immediate extinction. But we all recognized that there are always threats to manatees, and before we got into this event that’s ongoing on the Atlantic Coast we had these historical threats statewide to manatees. [These include] watercraft collisions that lead to mortality and the loss of warm water habitat. So no matter what those are the threats that are still here and are ongoing.
Then in addition in Southwest Florida, you have the red tide blooms that have been associated with mass mortality in manatees as well. So all that, you know, that’s enough threats to be concerned about the manatee population long-term, meaning they need management and protection. So now recently what you brought up we have this new threat that is centered in the Indian River Lagoon and that is the loss of seagrass. That has led to mass starvation unfortunately.
Dan Kolodny: Yeah, that’s hard to hear about, all these animals starving. So you said “big mortality” and the term I’ve heard thrown around a few times is “an unusual mortality event.” Can you kind of go into what that entails and what that definition means?
Dr. Martine de Wit: Yeah, yeah so an unusual mortality event or for short UME. It’s a federal declaration that comes from the Marine Mammal Protection Act and it’s assigned to stranding events that need attention. It could be because they are unusual findings or there is a large-scale die off, and those events need to be responded to.
So this is a federal declaration and sometimes it’s more like a bureaucracy, you know. It means extra paperwork for us because we respond to manatees no matter what but in this case when we had a UME declared in March of 2021 for the starvation event, it really helped us to bring in extra resources. The U.S. Fish and Wildlife Service and the state, they work together to set up an incident command system, ICS for short. [This] is a mechanism for disaster response.
For example, right now with Hurricane Ian it’s a perfect example [of] how all the response is being organized. So we had that same structure, a military structure if you will, to respond to the manatee problems associated with the Atlantic event.
Dan Kolodny: How are they trying to get a handle on the problem?
Dr. Martine de Wit: The real problem is the ill habitat, right? So we all recognize that habitat restoration is key and that’s the only solution for manatees long-term for their survival and that’s not something that can be done overnight. At least what this die-off did was it brought extra attention to what all of us who’ve worked in the lagoon for years, you know, we’ve known that there are problems. But at least, you know, manatees brought extra awareness and it came with extra funding so at least it helps to get some more of those projects for restoration off the ground.
So besides that, you know, realizing that this is gonna be something that’s gonna be long-term. In the short-term, there are several things that we did to help manatees pull through.
Like one of the first things that we always do is rescue live manatees that are sick, and in this case emaciated manatees. So there’s this great collaboration within the manatee rehabilitation partnership where we as the state, as FWC, are the First Responders to rescue the manatees, and then we bring them to the critical care facilities to get treated. So this really, I would say takes a village, but in this case it took more than that, and the country.
We have facilities out-of-state as well, so everyone worked together to be able to house as many manatees as possible that were rescued and needed treatment. And they were actually really successful. They got the best clinical care that you can even think of for a manatee and it takes a long time. It takes months for these animals to turn around but many of them have been released again so it’s a great example of the successes that we can do with rehabilitation.
Dan Kolodny: That’s great to hear that they actually survive the experience. So you said it takes a couple months for a manatee to be returned?
Dr. Martine de Wit: At least, for these cases that were thin and emaciated, at least four to five months. But you know some animals almost look like skeletons when we rescue them and even those animals, you know, slowly put on back weight with the right care and were able to be released.
Dan Kolodny: That’s great. And so I know that cold stress is a big issue for them, you know, on top of this emaciation. So in the winter, I know last winter, there was some feeding going on. Can you talk about that provisioning a little bit?
Dr. Martine de Wit: Yeah, you hit the point there. This starvation and the lack of food, that’s a year-round problem, but we see during the winter when you have that extra stressor of cold on these animals that are already in poor condition that that really pushes them over the edge.
So what we did last winter was an emergency action for supplemental feeding, and it was the first time that was ever attempted large-scale for a marine mammal—it really was an emergency action. It was meant as a Band-Aid because we know that these animals…you cannot feed them enough in the wild to put on weights but the manatees that, you know, were just in good enough health just to pull them through that winter when they have that extra stressor of cold. That was the aim, to help them a little bit. Then once spring is here they can venture out again and seek food for themselves.
So, yes, the U.S. Fish and Wildlife Service and the state organized this supplemental feeding program and manatees ate a bit more: over 200,000 pounds of lettuce and produce over a couple of months.
Dan Kolodny: Wow. How many animals do you think that would translate to, roughly?
Dr. Martine de Wit: Yeah, well, you know, it was interesting that like on the peak day when it was the coldest day of the year—and remember we did this at the FPNL Canaveral Plant where we had this temporary response field station set up to do this—so the animals already came there for the warm water and then, you know, got the food there as well. So on the coldest days there were more than 700 manatees counted in that area. We do not know how many actually ate it and how much they ate.
You know, over winter obviously those numbers went down and, you know, there were maybe a couple manatees or tens of manatees. It’s impossible to tell how many manatees actually ate and how much they ate. Like I said, it’s just a Band-Aid. Like manatees normally they eat about seven percent of their body weight so for an adult manatee that weighs about 1,000 pounds, if they eat a lot that can be 100 pounds per day. Obviously we couldn’t feed that much.
Dan Kolodny: That’s right and they don’t eat just seagrass. I mean, they’re pretty opportunistic, right? They’ll eat just about anything they can find that’s vegetative, right?
Dr. Martine de Wit: Yeah, seagrass is their main diet but if seagrass is not around they will turn to other sorts of vegetation and I think that’s also one of the reasons why it took a while for this starvation event to develop because we know that seagrass was in decline for a decade now and manatees turn to other food sources. Initially you had a lot of this surface vegetation, the macro algae. We know that there were a lot of animals who switched their diet to that. So when there’s no seagrass they will try other sorts of vegetation.
Dan Kolodny: Yeah and we’ve seen so much of this caulerpa resurgence in the lagoon. Is there any indication that they eat that at all or?
Dr. Martine de Wit: Yep, yeah, we’ve done some analysis on stomach contents where we found the caulerpa. We’ve also had field observations of manatees eating it. It just doesn’t seem to be very tasty and they are animals who, based on tracking records that we have with their GPS trackers, they will pass by these caulerpa beds and they won’t touch it. So I think it’s like a personal preference, and it’s not the most tastiest of vegetation out there.
Dan Kolodny: Gotcha. And so just to clarify for our listeners, caulerpa is a type of macro algae that looks a lot like seagrass from above and until you actually dig down in the water you can actually see the difference between what a caulerpa and seagrass is.
So, Martine, what’s the benefit of manatees? What do they bring to the IRL and to the environment as a whole? What’s the importance of manatees in the ecosystem?
Dr. Martine de Wit: Yeah, well, you know, everyone has their own reasons to be interested in them. I think it speaks for themselves that you know they’re a symbol of Florida. Like they’ve been around for millions and millions of years. It’s a shame if they go extinct. And they may not go extinct in other parts of the state. Like manatees on the Gulf Coast are doing well, St John’s River system too, but you know it tells you something if you have a habitat that has hosted manatees for so long and now there’s something wrong with it.
So that not only affects manatees, it affects the whole ecosystem. Even if you do not care for manatees per se, if you care about Florida and its environment, manatees are just a symbol. If you can keep manatees around that means that your ecosystem is healthy enough for all the wildlife out there.
Dan Kolodny: I’m glad you touched on that a little bit because, you know, I always hear people say, “Well, they’re eating all the seagrasses trying to come back and they’re going to prohibit expansion of seagrass beds” so I’m glad you touched on that that they’re not going to impact in a negative way.
Dr. Martine de Wit: If you are trying restoration and you have, like, the little sprouts growing and a manatee finds that, you know, I know there have been some failures on that end where manatees ate the sprouts. But in the big picture it should not matter, and manatees keep the seagrasses healthy. We just have to get past that breaking point right now.
Dan Kolodny: For me personally, it always brings you some sense of joy when you see them out there because they, you know, people love megafauna like dolphins and big animals and so you know I can always think back to some of my first experiences out on the lagoon and being out there fishing and this thing pops up and, you know, “What the heck is that?” and there’s this manatee just hanging out, you know. Kind of like asking you, “What are you catching? What’s going on?” So they’re always fun to see out there.
What can people do to help manatee populations, you know, what can an individual do? What’s some of the behaviors they can do or organizations they can donate to?
Dr. Martine de Wit: Yeah, so there are a couple of things people can do directly like we’ve talked about the dead manatees and the sick and the injured manatees. The way that we as First Responders learn about those animals is really from the people, the public, who are out on the water or who live on the water. We really rely on those reports.
So anyone who sees a sick or injured or dead manatee can call the Wildlife Hotline. That’s 1-888-404-3922, and the dispatch center will put the caller in direct contact with one of our local biologists. That way we can intervene and respond when needed. So that’s a very important way for people to be involved.
Otherwise if you’re out on the water boating, always be mindful manatees are out there even if you’re not in a manatee zone. Manatees can be everywhere so it’s always helpful to keep your eyes out and wearing polarized classes will help spot them and slow down if you are close to one. You can also look for the footprints. Those are circles in the water that they leave with their fluke when they swim.
Dan Kolodny: I was just going to mention that, yep.
Dr. Martine de Wit: Yeah, yeah and you know, otherwise obey the speed zones obviously. If you see manatees, keep them wild so don’t interact with them, keep your distance but, you know, watch them from afar. Also, keep the waterways clean. Simple things like trash, and you know, fishing line. Wildlife, including manatees, can be harmed by that. Manatees can ingest it, [and] they can get entangled in it, so keep the waterways clean.
Otherwise you mentioned financial support. If you live in Florida and you renew your license plate, the Save a Manatee license plate supports our manatee work. You can also purchase a decal, and then the supplemental feeding that we talked about earlier that was mostly paid for by public donations. I believe only 250 dollars came from a different pot, but almost everything was paid for by public donations through the Fish and Wildlife Foundation. So people can go there and donate to that and the website for that is wildlifeflorida.org.
Dan Kolodny: So with all that’s being done, you know, and like you said, this has brought so much attention to the habitat and working with the NEP, we’re trying to promote this habitat restoration. Are you hopeful that, you know, we can turn this around and make it so it’s suitable for manatees in the future?
Dr. Martine de Wit: You always have to be hopeful. You know, obviously from my end I see the bad and the worst of the dead and the sick manatees, but you know if nothing else it, um, we can use that to bring awareness and get everyone working on improving this habitat.
I know there are many bright minds and colleagues working on that, so yeah, you have to be hopeful. And manatees are resilient, and they’re still doing okay in other parts of the state, so that gives us hope that we can turn this around for manatees.
And it’s just the little sightings. If I can give an example, we had a manatee sighting in Georgia over the summer and this manatee was matched based on her scar pattern as seen this winter at the supplemental feeding station, and in Georgia she was seen with a small calf so you know that gives you hope because you know this starvation it’s a horrible condition. There are great concerns for chronic health issues and the declining reproduction so anecdotal reports like that means something that there is hope.
Dan Kolodny: That’s great. Is there any way the public can stay informed on how manatees are doing or how they’re progressing? Is there like a website or a bulletin that you have that you post somewhere that kind of has an update on how they’re doing?
Dr. Martine de Wit: Yeah, yeah, so we provide manatee updates, especially when things will pick up again this winter because we do expect manatee problems to start to increase again when temperatures cool off. So we will provide more regular updates during that time and people can visit our website. That’s myfwc.com/research/manatee.
Dan Kolodny: Well, I want to thank Martine for joining me today on today’s podcast.
Dr. Martine de Wit: Appreciate your support.
Dan Kolodny: I just want to thank all our listeners today and if you enjoy these discussions about the IRL please like and subscribe to this podcast. To learn more about the IRLNEP, how you can get involved and tips on living lagoon friendly, or to purchase One Lagoon merchandise please visit us at onelagoon.org. Also to stay informed about lagoon news and upcoming events follow us on Facebook, Twitter, Instagram, TikTok, all at One Lagoon.