Home of the Manatee Veteran AquaNews correspondent Marie-Lys Bacchus is back in Belize for her second summer of field research with the Earthwatch 'Manatees in Belize' Research Project. Now into the second year of her Master's studies at Loma Linda University, California, Marie-Lys' has returned to a remote mangrove island off the coast of Belize, where she will conduct field research on manatees under the leadership of marine scientist Caryn Self-Sullivan (Texas A&M University).
Time to Say Goodbye
September 29, 2006
By Marie-Lys C. Bacchus
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We celebrated Earthwatch team #4's last night with a beach barbecue under a beautiful sunset.
Photo: Susan Oliver
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My last week of research in Belize went well. The Earthwatch volunteers and I collected habitat data (including water temperature, salinity and current) from several scan points that do not include resting holes. This should allow me to compare the habitat characteristics between areas that have resting holes and those that do not. Hopefully this will help me come closer to understanding why manatees use certain areas for resting, while avoiding others.
We celebrated the Earthwatch volunteers’ final night with a nice barbeque under a beautiful sunset, and then a talent show. It was a fun event with poetry and original songs about manatees, followed by a banana-eating contest! After the team left the following morning, I only had a few days left before heading home to the States.
I decided to spend a whole day at each of two scan points. One of these points might not include a resting hole – as we once thought – so I wanted to spend an entire day there to see if we could spot a manatee resting. Dorian Alvarez, a boat driver on our team, and I anchored in one spot for eight hours and took turns scanning for manatees.
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A close-up of a manatee on the Belizean Barrier Reef.
Photo: Marie-Lys Bacchus
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We spotted a manatee that was traveling through the area to an adjoining creek and cove. About an hour later, the same manatee came back through in the opposite direction; we knew it was the same one because there is no other outlet out of that cove. Since we had not seen a manatee resting there the whole summer, this seemed to indicate that manatees might not use this area as a resting hole, or at least not anymore.
The next day we spent another day at another scan point, and saw no manatees the whole day! This could mean that manatees do not use these resting holes every day. It would be useful to spend more whole days at these resting holes to try to understand when the manatees come to rest in these areas.
Now the summer has come to an end and it is time to start packing. It’s very hard to say good-bye to Caryn and everyone else on the island, especially since I don’t know when I will be back. Even though it’s hard to leave, I’m so appreciative for the experience that I’ve had here over the past two summers. Working with Caryn, observing manatees, meeting people from around the world, teaching them about manatees, and learning to appreciate simple island living – my manatee research in Belize has been an experience that I will always cherish.
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Left: One of the beautiful island sunsets that I will miss very much! (Photo by Susan Oliver)
Right: Caryn Self-Sullivan and I sharing a fun and relaxing time at the barbecue.
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Snorkelling in Fantasty Creek
September 17, 2006
By Marie-Lys C. Bacchus
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An arrow crab, perched atop an orange sponge attached to a mangrove root, poses for the camera.
Photo: Daniel Gonzalez
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Since research days on the boat are often hot, we like taking breaks to do one of our favorite activities: mangrove snorkeling!
This summer, my Belizean field assistant and boat driver, Gilroy Robinson, introduced us to a small creek weaving its way through the mangroves. Caryn Self-Sullivan had named it Fantasy Creek. I was a little puzzled at the name until I started snorkeling in the clear waters and taking a closer look at the mangrove roots.
What breath-taking colors and beauty! All along this creek, a myriad of multi-colored sponges – yellow, orange, purple, blue and green – cling to the mangrove roots, with countless fish and other creatures hiding among them and swimming through this underwater rainbow. The amount of life among the mangrove roots – and its importance to the marine environment – is truly amazing!
Besides being an important home to manatees, birds, and invertebrates, mangrove islands also play other roles. They protect the Belizean coastline from storms and hurricanes, filter toxic components from the water, and keep valuable soil from eroding away. The many people building resorts on the mangrove islands, however, are cutting down the mangroves and building seawalls to try to keep the sea from washing away the sand they’ve brought to the island. While the soon sea wins and slowly eats away at the edges of the beach, islands with mangroves left intact have no such problems.
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One of the beautiful and ethereal feather-duster worms.
Photo: Marie-Lys Bacchus
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One of the most important roles of mangrove stands is as a nursery and home for fish and other sea creatures. There are countless small, silvery fish swimming around, as well as bigger fish, like barracuda, sheepshead and snappers.
If you look closely, you can often spot lobsters and crabs, as well as seastars, brittle stars, sea horses, tunicates, anemones and worms. There may also be sea cucumbers and conchs hiding among the seagrass beds that grow close to the mangrove roots. And, if you’re lucky and very quiet, you may even come across a manatee resting and feeding in a quiet area!
All this makes for a fascinating snorkel excursion in a habitat that is different than the reef, but still very rich. After our cool-off session, everyone is ready to get back to work on the hot boats. We carry with us unforgettable memories of the breathtakingly colourful life in Fantasy Creek.
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Night Scans
September 4, 2006
By Marie-Lys C. Bacchus
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Scanning for manatees at night using one of the powerful spotlights to try to catch a glimpse of a manatee taking a breath.
Photo: Marie-Lys Bacchus
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Scanning for manatees at night tends to be a different experience than during the day. The night sky is filled with an amazing panoply of stars, and we can clearly see the Milky Way as well as multiple shooting stars to wish upon. The wake of the boat weaves a trail of fluorescence in the water, and glow worms can be seen releasing their eggs as bright greenish spots at the surface. Our spotlights often attract insects, which then attract a multitude of fish and juvenile blue crabs, hunting for food.
So far the night scans have yielded no manatees. Haydee, one of the interns, and I are pretty sure we saw a "footprint" one night, and we may have heard a breath on another night. But nothing more concrete than that. With our spotlights trained on the resting holes, I feel pretty confident that we will see a manatee if it is present.
What does it mean if we're not seeing manatees? It could mean that our lights are too bright and scaring the manatees even before they come into the resting hole. The lights are very bright, but we try to keep them pointed at the mangroves and use the light which reflects onto the water from the mangroves to look for manatees. This should insure a minimal amount of light penetration into the water.
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Caryn Self-Sullivan (l), our boat driver Gilroy Robinson (r) and I discuss the best way to use the lights at night to spot manatees.
Photo: Sarah Delaney
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The spotlights seem to be the only sure way of seeing a resting manatee, especially on the darkest nights when the moon is absent. On the other hand, I think that the manatee breath sounds would be loud enough to hear when they are approaching these holes to rest at night. We might not hear every breath, since some manatees can breathe very quietly, but over the course of several weeks I would imagine that we should at least hear the loud ones taking a breath.
With only one possible breath noted during our night scans, perhaps this means the manatees are using the resting holes differently at night. Maybe they go to different areas away from the resting holes or do different activities during the night.
On the last night that the Earthwatch volunteers were here, I did a night scan with a group of students from Texas A&M, who were here with Dr. Chris Marshall for a Sirenian college course. A sliver of the moon was showing, while a light wind kissed our faces. With these conditions I
decided to try one night with no lights, just watching and listening by moonlight.
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Ashley uses a flashlight to help Susan measure sea surface salinity in the refractometer.
Photo: Marie-Lys Bacchus
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Unfortunately, the moon was setting towards the end of our thirty-minute scan, so the night turned very dark indeed. However, I think it would be worth another "no lights" night scan on a night with a full moon and no wind, comparing the detection of manatees with and without the lights. This may indicate that the lights are frightening the manatees, although moonlight may also play a part in the animals' movements.
Overall, the night scans have been very frustrating for me. Even if the lack of nocturnal sightings supports a theory that the manatees have different uses for resting holes at day and at night, how will I know for sure? I console myself by thinking that future researchers will be able to use my findings to design further studies to help us better understand the manatees and their environment.
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A Few Days Off
August 18, 2006
By Marie-Lys C. Bacchus
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Austin and Marie-Lys inside Actun Tunichil Muknal, the "Cave of the Crystal Maiden".
Photo: Marie-Lys Bacchus
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It was really nice to have my husband, Austin, visiting me for a week. I took a few days off from research, and we headed inland to San Jose Succotz, a small town near the Guatemalan border, and stayed at a little eco-tourist jungle hotel called The Trek Stop.
We had a most relaxing time reading books together, eating good food and talking. We also spent one day visiting Actun Tunichil Muknal, also known as “The Cave of the Crystal Maiden.” I had seen articles about it in National Geographic, and it was one of the best excursions I’ve ever done.
We hiked for about 45 minutes into the jungle and arrived at the mouth of a cave with an underground river running through it. We swam into the cave, then hiked and swam up the river for about 500 meters before climbing out into a huge dry cavern. The Mayans revered the cave as a very sacred area – a doorway to the underworld – and the walls and floor of this area were covered with broken pots which the Mayans used to offer drink and food sacrifices to their gods. Further back in the cave, we also saw several piles of preserved bones and skulls, including the complete skeleton of a young woman that had crystallized over the 1000 years or more that it had rested there. It was a great and muddy adventure!
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Marie-Lys teaches husband Austin how to operate the water sampling device at a resting hole.
Photo: Marie-Lys Bacchus
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Back to Work
After a few days of jungle excursions, we headed back to Spanish Bay to resume my manatee research. We characterized another resting hole, taking the usual measurements of water temperature, current speed and direction, and hole dimensions. We used the sonar to measure the edges of the resting hole and map it out with a global positioning system (GPS). This was the deepest resting hole I’ve measured so far: 5.3 meters deep, in comparison to the surrounding area which was about 3.6 meters below the surface of the water.
The following day, we spent a whole day at a single resting hole, from high tide to low tide, trying to better understand the pattern of manatees coming and going at that particular resting hole. It was a long time to sit in one place and quietly watch the water, and I know my husband, Austin, was feeling pretty stir-crazy by the end of the day!
On the final day before the next group of Earthwatch volunteers arrived, we zoomed around to as many of the official scan points as possible, taking water velocity measurements. The scan points are located in many different areas: open ocean, near seagrass beds, near the reef, and in quiet secluded mangrove coves. By taking measurements in various environments, we will be able to look for trends between those environments, water velocity measurements and the frequencies with which manatees visit those scan points. When I go back to the United States, I will be using all this data to build computerized maps to help researchers better understand how manatees use resting holes.
Austin’s week with me has passed all too quickly, as usual. Now he has gone home to the United States, and I am awaiting the arrival of the next group of volunteers. While one round of research experiences has ended, another has just begun!
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Notes from a Manatee Researcher's Spouse
August 10, 2006
By Austin Bacchus, husband of Marie-Lys Bacchus
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Austin contributes to the research effort by lying quietly in the boat and staying out of the way.
Photo: Marie-Lys Bacchus
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Here I am in Belize again, visiting Marie-Lys after half a summer apart. For the past five weeks, I've been living vicariously through her emails, pictures, Aquanews articles, and (too-short) phone calls. But, now I'll again be able to experience all the action myself! Last year, I saw three manatees in a single day while visiting. Will today's boat excursion top that? We'll see!
9:00am: We are now well-fed, well-sunscreened, and well on our way. The boat has left Spanish Bay, driven by Dorian (one of our local boat drivers and fellow manatee enthusiasts). The three of us will spend the whole day at a single manatee "resting hole" from high tide to low tide, counting the number of manatees that show up. Hmm… a whole day of sitting in a boat under a clear sky, with no cell phones or pagers in sight? Sounds terrific!
10:30am: We're off to a slow start so far. We've been anchored at the mouth of the cove which contains the resting hole for about 30 minutes with no sign of manatees yet. I've been playing with the GPS, the sonar, the salinometer (a device that tells you how salty the water is) and reading a book to pass the time. My job is to stay as quiet as possible, trying not to bump the sides of the boat or make noise, while Marie-Lys and Dorian take turns scanning the water and listening for manatee breath-sounds. It feels like hours have gone by.
12:30pm: I had no idea how hungry I could get from waiting and watching! We've just downed a typical mid-day "research meal" of fresh vegetables, beans, and tortillas. Part-way through our meal, our first manatee of the day showed up! It didn't stay for long, just taking one breath at the surface and then heading back out of the cove.
2:00pm: I've always thought of "field research" as exciting first-hand animal encounters, thrilling discoveries and enthralling observations. But that isn't the whole story! It seems like the majority of field research involves making careful observations and staying awake. Marie-Lys keeps saying encouraging things like, "Hey at least we saw one manatee today," or "Only 5 more hours to go," but I'm having a hard time paying attention to the featureless water. What kind of dedication and single-mindedness does it take to do field research? The answer: more than I have! It's a good thing that my wife is such a determined researcher.
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Marie-Lys uses a refractometer to determine the salinity of a water sample.
Photo: Austin Bacchus
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3:50pm: Another manatee has just entered the resting hole! We've counted about five or six breaths now, each about five minutes apart. This indicates that the manatee is hovering up and down in the resting hole, rising to take a breath, then sinking down to rest or even sleep. So that makes two manatees for the day (so far). I hope we see more.
5:00pm: I am convinced the manatees are mocking me. I was tired and hot from sitting on the boat, so I slipped over the side and went for a swim away from the cove. During the short 15 minutes that I was gone, a manatee swam right by the boat, and I missed all the action!
7:00pm: We're headed back to the island at the end of our day. I'm exhausted (and I really haven't done anything today), I'm hungry, sweaty and very thirsty! But all in all, it's been a productive day for Marie-Lys' research, with three manatee sightings. It has been a learning experience for me as well. I've learned that I will definitely need to increase my capacity for sitting quietly, if I ever want Marie-Lys to take me along on her research outings again!
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Staking Out A Manatee August 3, 2006 By Marie-Lys C. Bacchus  | A manatee watches us as it rests in the water over a coral reef. Photo: Daniel Gonzalez | Our first few weeks of research have been busy – we have conductedseveral manatee scans, both during the day and at night. At night we train spotlights on the resting holes, so if a manatee is resting in the area we should be able to see it. Sound is also very important at night, since we can often hear a manatee take a breath before we see it, but so far we have seen no signs of manatees at night. A fellow student, Daniel Gonzalez, came to Belize to help me test side-scan sonar as an extra tool to help us understand what the resting holes look like and how big they are. He has successfully used this technology to capture images of manatees in the water, and I am hoping that this might help me spot manatees at night. So far, though, we've had no encounters with manatees using the sonar. Reef Encounter Last week we had an opportunity to snorkel on the reef during the day, and we twice sighted a manatee resting near the reef crest in a little patch of sand surrounded by coral. He was easily identifiable by a little nick in his paddle on the left side. It was fascinating to hang motionless in the water, staring into the eyes of a manatee and wondering who, really, was studying whom. Homing in on Habitat Caryn (Self-Sullivan, a manatee expert and my Earthwatch supervisor in Belize) has noticed that every manatee on the reef whose gender she has identified is male. This may be because the males are using the reef as a corridor to move from one area to another in search of receptive females. There are plenty of rest areas and tasty seagrass beds near the reef, making it good habitat for manatees, despite a lack of freshwater.
(Although the local manatees live in a marine environment, they still need to obtain freshwater from somewhere; possibly from freshwater seeps at various places in the mangroves, or from rainwater or the nearby Belize River.) While Caryn Self-Sullivan and her colleague Katie LaCommare are trying to understand the overall pattern of habitat utilization of manatees in the Drowned Cayes, I'm looking at reasons why manatees might use particular areas as resting holes. Could it be because these areas tend to be in quiet, dead-end areas where there is virtually no current, minimal wind and wave action, and little boat traffic? These are only some of the questions that my research may begin to answer.
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Back in Belize July 28, 2006 By Marie-Lys C. Bacchus  | The second Earthwatch team of 2006 collects environmental data including water temperature, salinity, and a bottom-water sample from a resting hole. Photo: Emily Bowen-Moore | It was a wet and cloudy morning as I made my way to the boat that would take me back to the Drowned Cayes, about 30 minutes east off the coast of Belize City. I was excited to arrive at the island where I would spend another summer doing more research with the Antillean manatee, Trichechus manatus manatus. The Drowned Cayes, where I am conducting my research this summer, is a string of mangrove islands with very little actual land. Extensive sea grass beds surrounding these islands make it an ideal spot for manatees, providing excellent opportunities to deepen our understanding of habitat preferences of the Antillean manatees. As tourism and boat traffic have increased in Belize over the past few years, manatee habitat is being lost and their primary food source, seagrass beds, are being destroyed. To better understand the manatees' habitat preferences, it is important to determine whether the two sub-species of the West Indian manatee (the Florida manatee, T. m. latirostris, and the Antillean manatee, T. m. manatus) are influenced by different factors. The Antillean manatee has not been as well studied as its Florida cousin, and a wealth of information could be gleaned from research on the population in Belize. This year I want to take a closer look at the characteristics of resting holes, which seem to be very important to Antillean manatees. The manatees excavate and maintain a “hole” about 1–1.5 metres deeper than the surrounding substrate, and return there regularly to rest. These holes tend to be located in small coves and lagoons between the mangrove islands,  | | Our Belizean skipper, Gilroy Robinson, uses a water sampler to collect a sample from the bottom of a resting hole. Photo: Sarah Delaney | where there is minimal disturbance from boats. Here in the Drowned Cayes, Antillean manatees return faithfully to particular resting holes. Why would they choose and maintain these specific areas over the years to rest in? My research this summer will begin to address this question. In addition to comparing the nocturnal/diurnal use of resting holes, which is the project I started last summer, I also want to measure the depth, width, salinity, temperature, and type of substrate and vegetation in and around these holes. My research on manatees adds to the work that Caryn Self-Sullivan and Katie LaCommare have been conducting in this area for years. I trust that my small part in the overall project will help ensure that this important habitat will be protected for use by future generations of manatees.
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