Anjani Ganase, Trinbagonian marine biologist, continues her exploration of marine Tobago. In this issue, she discusses the work of Dr Michelle Cazabon-Mannette who surveyed sea turtles on the reefs of Tobago.This feature was first published in the Tobago Newsday on July 28, 2016. Follow Anjani Ganase on twitter @AnjGanase
In some of these columns, I will share the stories of other persons who are connected to coral reefs and the ocean. These connections are made in many ways, through occupation, research, sports or leisure. I will begin with marine biologist, Dr. Michelle Cazabon-Mannette, who grew up in the north of Trinidad and was always curious about the natural world. This curiosity eventually led to her discovery of the underwater world when – at 16 - she got the opportunity to learn to dive in the British Virgin Islands. This opened up a new world for exploration, and she continued to scuba dive on the reefs of Tobago. Her interest in the marine world developed with her studies in science, and she eventually focused on the life history of sea turtles.
|Dr Michelle Cazabon-Mannette and a Hawksbill turtle, photo by Lee Ann Beddoe|
Not much is known about the life of the sea turtle as it spends 99% of its life offshore. Currently, the bulk of the research is focused on the one percent of the life when female sea turtles return to their natal shores to nest. This occurs at a minimum of fifteen years after they were born and not much is known about their movements and habits before nesting, or even between breeding seasons. Michelle earnestly wanted to help fill this gap of knowledge. Knowing that the reefs of Tobago were home to young Green and Hawksbill turtles – which she saw on recreational dives - she sought to use these reefs as her study site towards her PhD at the University of the West Indies.
It was essential to first get an idea about the population numbers of Green and Hawksbill turtles living on reefs around Tobago, since no monitoring programmes had ever been done on these non-nesting turtles before. To do this, she regularly dived several reef sites along Tobago, both on the leeward and windward sides of the island, to get an estimate of turtle numbers and age groups by measuring and recording the sizes of their shells. It was generally understood that turtles that live along our reefs were born on beaches far away from this island, and Michelle wanted to find out where our local populations were born. In her surveys, she took samples of tissue to do genetic work. Her analyses suggest that most of the juvenile hawksbills foraging around Tobago come from nesting beaches in Cuba, Barbados and Puerto Rico. Imagine Cuban turtles living on our reefs! These are the true citizens of the Caribbean, mating and nesting in places, such as Cuba and Puerto Rico, then foraging and growing in Tobago.
There was another purpose to understanding the sea turtle populations along Tobago reefs and their connections with other Caribbean islands. Prior to 2011, it was legal to harvest sea turtles at sea in Trinidad and Tobago during part of the year, and unfortunately sea turtles continue to be taken from the sea and nesting beaches illegally and sold. Turtle meat may have been a viable product for fisherfolk, but globally, sea turtles are currently considered threatened with extinction. It is necessary to consider all the costs that come with purchasing turtle meat. It compromises the livelihoods of others who work and live alongside these ecosystems, whether it is through the tourism and fishing industry or the conservation efforts made by citizens not just locally but regionally.
Moreover, we need to assess the ecological value of the sea turtles that aid in maintaining healthy coral reefs and sea grass habitats. Green turtle foraging promotes healthy, productive sea grass habitats. By grazing the seagrass, they encourage the seagrass to grow quickly, but also maintain short blades so they don't get old and decay. All of this helps seagrass beds to stay healthy and support a diversity of species including commercial fish species. Green turtles and hawksbills also help promote healthy coral reefs by grazing on algae and sponges respectively. Algae and sponge, if left to grow unchecked, can overgrow coral and lead to a loss of diversity and contribute to deterioration of the ecosystem. Through the maintenance of these ecosystems, sea turtles enhance the fishing and tourism industries; they are our partners in ecosystem management.
One of the main goals of Michelle’s research was to understand the value that people placed on turtle conservation and the enjoyment of encountering turtles, while diving on Tobago reefs. The outcomes of these findings can aid in promoting alternate avenues for obtaining economic value through sea turtles conservation and possibly ecotourism. How we care or don’t care for the sea turtle will be felt much farther than our own shores in the south Caribbean, so it is our responsibility to be guardians of these creatures for the sake of all our coastal ecosystems and economies.
|Hawksbill turtles on the reef. Photo by Ryan P. Mannette|
Michelle is one among a new generation of Caribbean scientists who are going to ensure that the natural life of our islands is conserved. She is happy to share her information with youngsters who are interested in ocean sciences. She continues to do research on Tobago sea turtles and is actively involved in their conservation and protection. If you would like to know more about her research and local conservation efforts, you can follow her on twitter: @turtlegirl_TT. For more about her research, use this link: https://www.youtube.com/watch?v=6Xq7Bi_N76w, a short film ”Beyond The Beach” is based on the turtle monitoring programme designed and led by Michelle while working with turtle conservation organisations, Turtle Village Trust (TVT) in Trinidad and Save our Sea Turtles (SOS) in Tobago.
SOME EXPANDED ANSWERS FROM DR MICHELLE CAZABON-MANNETTE
Follow Michelle on twitter @turtlegirl_TT
Q What about turtles fascinated you enough to study them?
Sea turtles have a very mysterious life. They spend 99% of their lives at sea, and travel great distances, but most of what we know about them is based on what we can learn when females visit beaches to nest. Little by little more studies are giving us a look at what goes on with turtles the rest of the time, under the sea. After I graduated with my first degree in biology in 2005 and I was exploring ideas for research, I realized that here in Trinidad and Tobago, we are lucky to have hawksbill and green turtles feeding offshore. I saw it as a great mystery I could explore. It's always a thrill to see a turtle underwater - they are powerful swimmers and they move effortlessly through the water. They are also curious and sometimes approach you for a closer look too.
Q What is your research about and why are you interested in this?
For my PhD research, I set out to learn as much as I could about sea turtles offshore Tobago. Green and hawksbill turtles were harvested by fisherfolk, but there was no data on the population, or on the harvest. This was the big gap I wanted to address, so we could make informed decisions about the turtles and their harvest. I completed scuba dives around the island to learn where turtles could be found and how abundant they are. I used a questionnaire to learn about how many fishers harvested sea turtles, how many turtles they harvested and how much they relied on the income from turtles.
Besides the economic value of sea turtle products like meat and eggs, sea turtles can have value in other ways that may be overlooked because this value is not captured in any market or form of trade. We know that people will pay to see turtles nest on beaches, but what about the turtles that we have offshore? So I used questionnaires to learn about the economic value of turtles in terms of how much value people place on their conservation, and how much value turtles add to the experience of scuba diving. These are important values that are part of Tobago's tourism product.
Finally, based on other studies from the region, we understood that these sea turtles in Tobago's waters were born elsewhere in the region, and turtles nesting on our shores would spend most of their time far from our shores, but we didn't know if there was a strong link to any population in particular. I collected samples from hawksbills on our nesting beaches and at sea, and analysed their DNA to compare with other populations to understand how these turtles are linked to other countries in the region.
I was interested in all these areas because I wanted to gather important information for management, but I think this information is also of interest to the general public and can help inspire people to care about the conservation of these species.
Q What is the most interesting thing you've learned from your research, about the turtle population living on Tobago reefs?
The genetic results suggest that most of the juvenile hawksbills foraging around Tobago come from nesting beaches in Cuba, Barbados and Puerto Rico. Even though Tobago is quite a small island, the results from the genetic study also suggest that the group of hawksbill turtles feeding on the leeward coast is distinct from the group on the windward coast. We have some ideas why this might be the case, but more work has to be done to explore this.
Q What are the functional roles of turtles living on Tobago's coastal ecosystems and how are these roles important to the livelihood of Tobagonians?
Sea turtles rely on healthy coastal ecosystems, but they also help promote healthy coastal ecosystems. And healthy ecosystems provide us with goods and services that we all rely on, but they are especially important to anyone who makes a livelihood from fishing or tourism.
Green turtles promote healthy, productive seagrass habitats by grazing on the seagrass. By grazing, they encourage seagrasses to grow quickly, yet they keep the blades cropped short so they don't get old and decay. They also contribute to the cycling of nutrients. All of this helps seagrass beds to stay healthy and support a diversity of species including commercial fish species. Green turtles and hawksbills both help promote healthy coral reefs by grazing on algae and sponges respectively. Algae and sponge, if left to grow unchecked, can overgrow coral and lead to a loss of diversity and contribute to deterioration of the ecosystem. We all rely on coastal ecosystems to some extent, but that is especially true of anyone who makes a livelihood from fishing or tourism
Q How can people find out more about your research?
The thesis "Ecology and use of nearshore foraging sea turtle populations around Tobago, with an emphasis on hawksbills" will be lodged at Alma Jordan Library, UWI, St. Augustine by the end of 2016.
See also the film Beyond the Beach, protecting sea turtles, on youtube: