Friday, March 13, 2015

African Manatees Are Omnivores!

     There’s a good reason manatees are also known as Sea Cows. They’re often seen feeding in seagrass beds or along the banks of rivers, much as cows graze meadows on land. The Florida manatee, the most studied species, is believed to be a strict herbivore (although there have been occasional observations of them eating marine invertebrates, and recently fish). But during my ten years of work with African manatees, in almost every country I’ve visited, I’ve repeatedly heard stories from local people that manatees steal fish from nets, and that they eat clams and mollusks, both freshwater and marine varieties. At first I was surprised, because I thought African manatees would be just like their Florida cousins, but I heard these reports so often from people in countries thousands of miles apart, that I decided I had to investigate.

Fishermen in eastern Senegal show catfish heads left in nets after manatees ate the rest of the fish.
      African manatees are very hard to observe in the wild due to their shy nature and the murky water habitats they live in, so I decided to research their diet using a technique known as stable isotope analysis. The name sounds intimidating, but the concept of stable isotopes is really quite simple: every plant and animal has a unique carbon and nitrogen signature, which differs for lots of reasons including the attributes of environment they live in (rainfall, water quality, soil quality, pollution, etc.) and many other factors. By collecting samples of everything we think an organism eats from each habitat they live in, these signatures can be used to determine what makes up an animal’s diet.
       In my case, I collected plant, fish, and mollusk samples throughout manatee habitats in Senegal and Gabon, as well as bone samples from manatees from the same areas, to determine their average lifetime diets in the different habitats in which they lived. I was also able to sample manatee bones collected 70 years ago from a museum collection, so that I could compare manatee diet in the past to samples collected recently. Then I took all the samples to the laboratory, processed them to get their stable isotope values, input those values into an analysis program, and got some exciting results.

This is a manatee ear bone, sectioned to sample average lifetime diet.
        African manatees sampled from both Gabon and Senegal, and both freshwater and marine systems, regularly ate mollusks and fish as part of their diets. For Gabon manatees living in lagoons and rivers in the Central African rainforest, the model estimated their diet was 90% plants and 10% invertebrates (fish were not sampled from Gabon). In the Senegal River, for manatees living in a desert environment at the edge of the Sahara, plants composed 46 - 57% of diet. The remaining diet proportions were composed of mollusks (19 - 24%) and fish (24 - 27%). Manatees living along Senegal’s coast indicated a diet of 48% clams and 51% seagrass. So for manatees in Senegal, approximately 50% of their diets were not plants! For a species considered an herbivore, this is pretty big news. There was no significant difference between historical and recent manatee samples for either the Senegal River or the coast, and although sample sizes were small, this indicates that sampled manatees had similar diets throughout life, and that diet proportions have not changed significantly over the past 70 years.
      So why is this important? The results of this study give us accurate information about the food resources manatees utilize over time in the different habitats they live in. This can help resource managers prioritize specific places where food resources are abundant for conservation purposes. This new information also increases the list of species we need to monitor as important food sources for manatees. For example, now that we know manatees in Senegal depend upon mollusks and fish, we need to try to resolve conflicts with fishermen and help to conserve not just the plants, but all the species manatees depend upon. This is the first dietary analysis study for the African manatee and I look forward to publishing the results in the scientific literature soon, and continuing my studies of manatee diet in other countries.

Friday, March 06, 2015

Back to Africa At Last!!

At the end of January I finished packing up and left Florida, which definitely was the end of an era for me. I moved there in May 1998 to begin a job with the Florida Fish and Wildlife Commission running a manatee research field station in southwest Florida. After 6 years I left that job to pursue international manatee work and began working in Africa in 2006. Although I've spent a lot of time in Africa since then, I returned to FL for my PhD in 2009, and my home base has been there until now. I'll miss my friends and colleagues there a lot, but it's time to get back to fieldwork and conservation on the ground in Africa.

After leaving Florida in early February, my husband Tomas and I drove north on our "Friends, Family and Funders" tour of the northeast. We spent 2 weeks in Washington DC and I gave presentations about my dissertation results and ongoing projects in Africa to the U.S. Marine Mammal Commission and the Fish and Wildlife Service. We also donated an African manatee skull to the Smithsonian Museum and were treated to an amazing behind the scenes tour of their marine mammal storage facility in Maryland by longtime curator Charley Potter and Dr. Daryl Domning.

Me, Tomas, and Dr. Domning with the skull we donated
Side by side comparison of West Indian (Florida), African, and Amazonian manatee skulls.
Ok, so it's not a manatee, but the blue whale skull at the Smithsonian facility was amazing!
On March 1 we flew back to Senegal, and we're currently setting up our home and office. I look forward to sharing more African manatee news and stories soon!

Tuesday, December 30, 2014

Happy New Year!!

I have no idea where the time went this past Fall! I apologize for my silence the past few months. I'm now wrapping up my work and life in Gainesville, FL and preparing for the big move back to Africa in March. I'll be based in Senegal and am very excited to get back to African manatee fieldwork.

Big things are coming for the African manatee project in 2015!  These include:
- continuing development of long-term study sites and partnerships in Senegal
- in collaboration with the USFWS, I'll begin a new two year training program for manatee graduate students from Central Africa, called MENTOR Manatee 
- continuation of support for our projects in Cameroon, Gabon, Nigeria, and Mali
- work on 7 manatee scientific manuscripts...hopefully several will be published in 2015!
- continuing African manatee population genetics in collaboration with colleagues at the USGS Sirenia Project
- and much more!

Wishing everyone a successful and happy 2015!

Friday, October 24, 2014

Senegal: Tocc Tocc Reserve update

It's been a busy summer and autumn for the EcoGuards and Community leaders at Tocc Tocc Reserve in northern Senegal. The EcoGuards are now patrolling the reserve full time, and we're fortunate to have raised enough funds for a second boat for the reserve, which allows more wildlife monitoring and patrols.
The EcoGuards confiscated and destroyed the first illegal fish traps in the reserve (after giving the owners warnings to remove them, which they did not). The installation of buoys marking the reserve boundaries now guarantee people are aware of the protected area, which aids in enforcement of the regulations. However, because the local community supports and oversees the reserve, there have been few instances of broken rules, and most of those cases came from seasonal fishermen from outside the community. Ten fishermen have been arrested and fined for violating no fishing rules within refuge. Funds collected from fines were used by the community conservation committee towards refuge costs. So we believe the reserve is now protecting all the wildlife that uses it.
Additionally, since educational programs began last year, we have received five reports of manatees entangled in fishing nets from villages outside the reserve. In four cases, the EcoGuards were able to safely release the manatees back to the wild, and in the fifth case the manatee had unfortunately drowned, but genetics samples were collected that are helping us further understand the Lac de Guiers manatee population. We believe the increase in the number of reported entangled manatees (none were reported before this project began) is a direct result of our educational outreach and awareness programs in the area. Now that all the abandoned nets have been removed, manatee sightings within the reserve have also greatly increased. Between April-June 2014, manatees were sighted almost every day, which is a very large increase over the previous year, when they were sighted only every few weeks.
Photo courtesy of Modou Diop Boh

In September, the first observation tower was completed, and eleven members of Senegal's parliament visited the refuge to see a good example of community-based conservation that can be used as a model for other sites in Senegal. It was a grand occasion with lots of speeches by the politicians and tours of the new tower.  
photos courtesy of Tomas Diagne
Next, we begin raising funds to build an education center at the reserve for the public and tourists.

Thursday, September 18, 2014

Welcome to Florida Aristide!

In late August, Aristide Kamla began his Fulbright scholarship towards his PhD at the College of Veterinary Medicine at the University of Florida. The college has just posted a very nice story about Aristide, which can be read here. I'm excited to continue collaborating with Aristide for African manatee baseline health and population studies in Cameroon!

Saturday, August 09, 2014


It was a very happy and emotional day for me yesterday- I graduated with my PhD from the Aquatic Animal Health program, College of Veterinary Medicine at the University of Florida! Eight years of sample collection and analysis, and 5 years of PhD program are finished! I'm incredibly grateful to all the many collaborators both in Africa and the USA who worked so closely with me to make this possible. My greatest hope is that the results will help the conservation of the African manatee, and I look forward to many more years of work with this unique and fascinating species.

Thursday, August 07, 2014

Recent African manatee network activities

In the past few months several network members have been very active with training, educational outreach and data presentation activities. Here are a few brief updates!

 In April, Aristide Kamla held his largest training workshop yet in Cameroon. This workshop was specifically for Biology Masters students from the University of Dschang, where Aristide completed his Masters degree several years ago. One young manatee researcher from Nigeria also attended. I was very happy my project could support this workshop, and to hear all the enthusiasm both from the students as well as the university faculty for the training, and for the opportunity to get out into the field. Apparently the university doesn't offer practical training to graduate students in the field, so this was a rare opportunity for Aristide to show them an active study site and how manatee research is conducted. The photo below shows participants, university staff and several invited speakers. Photo courtesy of A. Kamla.

In early July in Mali, Soumaila Berthe had a manatee educational booth at the World Environment festival in Bamako, which lasted for 2 weeks. He was able to raise awareness and give manatee information to hundreds of people. The project designed and distributed manatee stickers, informational pamphlets, and key rings. This was the first manatee awareness campaign in Bamako. Photo courtesy of S. Berthe.

 In mid-July this project supported Rodrigue Ngafack's travel from Cameroon to participate in the African Marine Mammal Colloquium in South Africa. He presented a poster on the results of his Masters research in Lake Ossa, Cameroon. This is the first time an African manatee presentation has been given at this conference, and we hope to increase presentations by other researchers in future years. Rodrigue really enjoyed the opportunity to meet other marine mammal researchers working in other parts of Africa. Photo courtesy of R. Ngafack.