My research on the physiology, ecology, and migration of
Costa Rican leatherback sea turtles has been instrumental in the establishment of
"Las Baulas De Guanacaste," a national park on Playa Grande, Playa Langosta, and
Playa Ventanas, Costa Rica. With help from EarthCorps volunteers, we are contributing to a
previously small body of sea-turtle information and developing an education program to
expose local people to the benefits of ecotourism and conservation.
Reminiscent of dinosaurs, the leatherback sea turtle has existed in its current form for over 20 million years. This rare and unique reptile spans waters between the tropics and the Arctic Circle, yet currently is under the threat of extinction. Despite the uniqueness of this species, very little is known about its zoogeography, ecology, behavior, or physiology. We are studying these gentle giants so that we can better understand them and ultimately help prevent egg depletion and nesting-beach destruction from ending the leatherback's 20-million-year history.
Weighing as much as 900 kilograms, leatherbacks are the world's largest reptiles; this is amazing, considering they eat only jellyfish, which are more than 95 percent water. Also amazing is the sea turtle's ability to change its body temperature. Although, like all reptiles, leatherbacks are ectothermic (cold-blooded), they can withstand a wide range of temperatures. Leatherbacks have been captured in cold (7 degrees Celcius) North Atlantic seas that would kill a human in less than ten minutes, yet have been found to have body temperatures of over 25 degrees Celcius; in one instance, we found a leatherback's body temperature rose one degree Celcius while the surrounding temperature dropped more than four degrees.
Unlike a warm-blooded mammal or a bird, the leatherback does not have a high metabolism. We have found that it stays warm because its fatty skin serves to insulate and retain the heat generated by its enormous body. This system of "Gigantothermy" may have also warmed the dinosaurs. Some scientists today speculate that dinosaurs may have been warm-blooded; our studies indicate that large reptiles do not necessarily have to undergo special physiological adaptations to keep themselves warm.
In order to better understand this mysterious and vanishing species, we are studying its behavior, physiology, and migration. Through observing and examining nesting females, we hope to learn more about leatherback ecology. What is the hatching success on Costa Rica's Pacific-coast beaches? How does nest location affect turtle offspring? What factors influence leatherback thermoregulation? Answers to these questions will help to establish the leatherback's survival needs. We also hope to encourage local Costa Ricans to participate in the long-range benefits of sea-turtle conservation and ecotourism, rather than the short-term benefits of using the rapidly disappearing egg supply for food.
Over the 1993 and 1994 field seasons, more than 125 volunteers participated in our population ecology and nesting-habitat research. Most volunteer work occurs during nightly three-to-four-hour beach walks. EarthCorps volunteers record nest positions, count the number of fertile and infertile eggs, and assist the staff in attaching microchip tags (PIT tags-Passive Inducive Transponders, or Personal Identification Tags) to the turtles. Other experiments include testing nest metabolism by analyzing gas samples in the nests and attaching satellite transmitters to the turtles' shells, so that migration patterns can be tracked.
Due to extensive, world-wide beach habitat destruction, only 20 major sea-turtle nesting beaches remain in the world. With 1,500 to 3,000 females nesting per year, the beach complex comprising Playa Grande, Playa Langosta, and Playa Ventanas is now the second most important of these nesting sites.
We have found that though there are almost three kilometers of beach, the turtles concentrate their nests in the middle one kilometer and that those central nests are also the most successful in hatching baby turtles. Our PIT-tag research indicates that these females return about 8 times in one nesting season to the same beach and lay 8 nests, 10 days apart, with about 80 eggs per nest. Only about 40 percent of the eggs hatch. We are also starting to get a handle on just how many female turtles there may be in this population. This research has helped us manage and conserve "Las Baulas De Guanacaste."
Our satellite telemetry work has enabled us to follow the females once they reach the Pacific Ocean. These leatherbacks do not just wander aimlessly; rather, they use specific migratory routes that pass through narrow corridors. This information is very important in developing international conservation plans, because we now know when and where to restrict long-line fishing and netting.
Overall, one of our greatest accomplishments is establishing the new national park. Volunteers built a bunk house for the park guards as well as an entry kiosk. Volunteers have also helped train local people to guide tours and continue leatherback conservation. We conduct local seminars and education projects that help show local people how they can manage newly established artisan and tour-guide cooperatives, as well as a conservation education program in the local schools.
-
| Hallet Cove South Primary | Kamo Elementary School | Central Primary School |