A beautiful Praying Mantis, SE Costa Rica!
The Race for Survival: Conservation of Leatherback Sea Turtles
The idea of dinosaurs currently roaming the Earth is an unbelievable, unimaginable concept. Nonetheless, a giant dinosaur-like creature roams our seas this very day; amazingly, spending 99.9% of its life on the bottom of the ocean (www.Leatherback.org). This elusive creature is a turtle; not any turtle, but the very mysterious leatherback sea turtle or Dermochelys coricacea (James et al. 2005). The leatherback turtle is the largest known turtle with a maximum size of ten feet and over 2,000 pounds. These enigmatic turtles have been shrouded in mystery due to their elusive lifestyle.
The Leatherback turtle varies from the other sea turtle species in multiple ways. One main variation is its carapace, which lacks horny scales on its plastron (www.Leatherback.org). This unique turtle migrates farther to the north and to the south than any other sea turtle species. For this reason, the Leatherback sea turtles can be found in every ocean of the world; one of only a few species. Most sea turtles are restricted to warm tropical waters because turtles are cold-blooded. However, the ability of the leatherback to regulate its blood flow to appendages allows it to combat the cold water expanding its range in the oceans. This evolutionary adaptation was likewise used by dinosaurs for thousands of years and is referred to as gigantothermy (Hickey 2000). This evolutionary adaptation allows the leatherback to prowl the ocean searching for its main source of food, the jellyfish (Stolzenberg 1993).
Leatherbacks have been around for thousands of years, one of the oldest known reptiles. Bones from a leatherback turtle have been carbon dated all the way back to the cretaceous period. This turtle has been able to stay structurally homologous to its ancestor through the years as most species around it became extinct or evolved radically. Their simple structure has allowed them to survive and thrive for thousands of years until recent complications from the human world (Ovetz 2004).
These ancient turtles still rely on the warm tropical oceans for it to lay its nest of eggs. Like many other reptiles the sex of the turtle hatchling is dependent on the heat of the nest during incubation. This is why hundreds of leatherbacks return to Costa Rica each nesting season. Like all other sea turtles the Leatherback sea turtle spends most of its life at sea except for the female’s nesting. In addition to Costa Rica, Leatherbacks are known to nest from Cape Sable to the Virgin Islands with twenty to thirty thousand females remaining worldwide (NOAA).
The Leatherback turtle’s shell is the main reason that this sea turtle is categorized into its own subspecies. The unique shell is not made of bone but of interlocking bony plates and a layer of fat. This leathery shell is highly aerodynamic which allows the turtle to swim at speeds of upwards of nine miles per hour. Therefore, Leatherbacks can easily swim great distances and dive to extreme depths. Their structural design and low bone to cartilage ratio help these turtles dive to depths near 3,000 feet deep (Tyson 1997). At that depth the leatherback is able to withstand the extreme pressure of about 1,500 PSI. The hostile environment at the bottom of the ocean would kill most creatures except for the highly adapted, ancient leatherbacks. Uniquely, the Leatherback’s evolution and adaptations allow it to spend almost its entire life underwater except for hatching and nesting. Nonetheless, the Leatherback has to deal with the destructive human impact on their life
Leatherback sea turtles have had to face numerous threats ranging from fishermen to curious tourists. Commercial fishermen drop trawling nets that entangle the turtles preventing them from resurfacing for air. Shrimping nets are one of the main causes of dearth among leatherback deaths from fishing. (Gilbertas 1998) Along with that the turtles sometimes think that these nets are its main food source jellyfish, taking a fatal bite of net or garbage. If the nets are not enough, the leatherbacks are sometimes used for bait to catch sharks in some parts of the world. These pelagic creatures, open ocean dwellers, are vulnerable to the net trawlers, feeding were most commercial fishermen cast their lines. Leatherbacks have few natural predators in the ocean but a few carcasses have been found in the stomachs of sharks and killer whales. Along with the numerous and various threats in the ocean, the perilous journey to the ocean by the hatchling is an additional obstacle to their survival.
Over the years the leatherback turtle population has been in decline at a very alarming rate earning them an endangered species (EN) rating by the World Conservation IUCN Red List of Threatened Species. Along with the many natural predators the hatchlings face, they also have to evade human encroachment. The numbers of the Pacific Leatherback have dropped drastically over recent years from 91,000 in 1980 to fewer than 1,500 in 2004 (Earthwatch Institute 2004).
The hatching of the baby turtles on tropical beaches has been a ritual of the leatherback since the cretaceous period. Only when it is the correct moon phase do the turtles return to land to nest for about two hours. This process is a very tedious process, exhausting them to tears. The tears are not from pain but to remove abrasive sand and salt from their eyes. For nesting to occur the turtles must use shovel like hind flippers to create a nest for egg incubation (Stolzenberg 1993). Nests are usually three feet deep, filled with about one hundred circular amniotic eggs. In the nest the uppermost thirty eggs are sterile, creating an incubation chamber as well as protection. Temperature for the eggs is crucial in determining the sex of the turtle much like that of other sea turtles. If the temperature is less than 25.9 degrees Celsius the turtle will be a male turtle (Gilbertas 1998). During the whole process of egg laying the leatherback is in an oblivious state of mind, a trance. An inquisitive tourist or a conservation worker could approach these gentle giants while egg lying without them knowing it. However, it is crucial to have a protected quiet area because the loud noises can disturb incoming turtles. Once again human invasion on the life of the leatherback can cause harmful effects on turtle populations.
Threats on the turtle nest come from all a wide variety of things ranging from mole crickets to other nesting sea turtles. Tourists have become a large problem in the leatherback conservation because they take the eggs from the nest. The common misconception is that they can raise these highly complicated ancient turtles in their homes. Additionally, many prime nesting areas are being invaded by the urban sprawl that develops the pristine beach real estate. The lights from beach homes can disturb the turtles, fooling them into thinking of the wrong lunar position. Their vulnerable exodus to the sea can be altered by their perception of human lights as the lunar light. In addition, the eggs and hatchings must survive a wide range of predators on land and at sea
Egg hatching in the nest is triggered by a chain reaction created when the first egg is hatched. The emergence of the hatchlings from their sand nests brings several types of predators to the beach like owls, vulture, herons, and once in the ocean the nesting shark. When the eggs hatch at night the stand a better chance at survival under the protection of the night. The chance of survival is very slim for these vulnerable hatchlings, but if they make into open ocean they may live a prosperous life.
Conservation of leatherback turtles has been focused on uncovering their mysterious life in the open ocean. Scientist are using all sorts of trackers ranging from GPS to tracking tags. As technology progressed the types of tags that have been improved to record more in-depth information. For the turtle conservation to be successful the scientist have to know where these large sea turtles are migrating. A scientist by the name of Eckert developed a TDR or a microprocessor controlled time depth recorder to track the turtles (Tyson 1997). These bulky devices are strapped to the turtle’s shell to relay information on their migrational pattern. Efforts by Dr. James Spitola have greatly increased the knowledge on the migrational patterns by the leatherback off the Costa Rican coast (Wuethrich 1993). However, a problem developed with tracking TDR equipped leatherbacks because there was a lack of signals being received by the satellite. The problem was the turtles were not surfacing for the needed 5 minutes for a satellite to acquire a fix on the turtle’s location. So Eckert devised another system using GPS, shortening the surfacing time to less than 20 seconds (Tyson 1997).
GPS systems provided many advantages over TDRs besides the shortened surfacing time. The transmitters can be turned on or off at any moment allowing the scientist to collect the needed data. Along with that the GPS trackers can be programmed to detach form the turtles once the needed information is collected. The GPS locators have unlocked the secret of the leatherbacks by locating their undersea migration highways. These undersea highways correspond to oceanographic movements and currents in the world’s seas (Hays et al 2003). With this information the conservation workers can alert the fisherman of the leatherback’s migration patterns. This will in turn potentially save thousands of turtle from dying in trawling nets. Technology has ironically become the number one reason for conservation of these ancient creatures.
The conservation effort for this creature has helped it survive very grim predictions projected from the population decline. However, the improvement in tracking and overall efforts of conservation workers has turned this species around, saving it from extinction. Awareness of information on the leatherback turtles to the public will be key for a continued increase in leatherback population. Public awareness coupled with the innovations in technology like TEDs, GPS trackers, and TDRs, will help revive the turtle population. The NOAA has reported that with new technology like the TEDs the annual deaths of leatherbacks will decrease by 97% (Earth Island Journal 2004). These gentle giants of the ocean have thrived for millions of year but are now threatened by our way of life. Now it is up to all of us to save these magnificent creatures of the sea.
Gilbertas, Bernadette. “Up From the Sand.” International Wildlife 1998 Sept/Oct:30-36
“Good News for Turtles.” Earth Island Journal 2004; 18(4): 7
Hickey, Georgina. “Life on a Diet of Cold Jelly.” Nature Australia 2000; 26: 11.
Hays, Graeme; Luschi, Paolo; and Papi, Floriano. A review of long-distance movements by marine turtles, and the possible role of ocean currents. Oikos 2004 Nov; 103(2): 293.
“Impressive Results.” Earthwach Institute Journal 2004; 22(3): 5-6.
James, Michael; Ottensmeyer, Andrea; and Myers, Ransom. Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letters 2005; 8: 195-202.
Leatherback Sea turtle: Endangered species [Internet].National Oceanic and Atmospheric Administration (US); [updated 2005 May 12; cited 2005 May 13] Available from www.nmfs.noaa.gov/pr/species/turtles
The Leatherback Trust [Internet]. The Leatherback.org; [updated 2005; cited 2005 May 13] Available from www.leatherback.org/
Ovetz, Robert. “100,000,000 years old. 10 years left to live.” Ecologist 2004 Mar; 34: 48-52.
Stolzenberg, William. “Requiem for the ancient mariner.” Sea Frontiers 1993 Mar/Apr; 39(2): 16-19.
Tyson, Peter. “High-tech Help for Ancient Turtles.” MIT’s Technology Review 1997 Nov/Dec: 54-61.
Wuethrich, Bernice. “Tracking turtles’ ocean highways.” New Scientist; 138(1868): 8.
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