Green Sea Turtle Conservation and Species Awareness (Final Paper)

This topic submitted by Meghan Scanlon ( Scanlom2@miamioh.edu) at 11:03 PM on 6/9/07.

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Green Sea Turtle Conservation and Species Awareness


The Green Sea Turtle (Chelonia mydas) is one of eight species of sea turtles that are endangered due to human cause. They have always been creatures of high demand with their shells prized for itŐs use in jewelry and beads and their bodies wanted for meat. The high demand as well as many other environmental factors including human influence has caused the decline of the species. Many conservation efforts have been established but there is still more to be done in order to save the species. The most important thing that can be done for this species is to make the public aware of their actions that harm the turtles and how they can change their ways.
The Green Sea turtle has a large range of sea that they live in. They are found in the Atlantic Ocean from Massachusetts through to Florida as well as in the Gulf of Mexico and the Caribbean Sea. They are also found in other parts of the world such as the warm waters of the Mediterranean Sea. Although some Green Sea turtles have been seen living as far up north as Massachusetts they generally stay in more temperate and tropical waters. Within these living areas the adult Green turtles tend to stay near coastlines or islands; basically areas where there are bays and other protected shores with plenty of nutrition easily accessible. Such protected areas include Inlets, estuaries, and coral reefs where there is plenty of submerged vegetation including sea grass meadows and algae. They are very rarely found in the open ocean, usually when spotted far from shore they are traveling to distant nesting locations and feeding grounds. These Green Sea turtles are known to travel up to one thousand and four hundred miles between their feeding grounds and nesting site.
The Green Sea Turtle has a large, hard shell that surrounds itŐs body, leaving only the head and appendages outside of the shell. These shells are composed of two main parts: the carapaces and plastrons. The Carapace is the section of shell that covers the turtlesŐ backs and is comprised of four large coastal plates on each side with a some what bony layer of jointed scales; it can measure up to three feet in length. The plastron is the section of the shell that covers the bellies of the turtlesŐ and tends to be smoother and less bony then the Carapace. These two parts making up the shell are connected by a series of tiny bones connected together to form a ridged connecting bridge securing the two together (EBSCO, 6). The shell of a Green Sea Turtle serves as itŐs skeleton in that it supports, protects and holds together all of itŐs inner organs. It would be impossible for these turtles to survive without their shells; it would be like humans without their skeletal system. The shell provides the turtle with protection against many bodily injuries but it does not protect the turtles most valuable asset, itŐs head. The turtle is unable to retreat itŐs head into itŐs shell for protection, therefore making it vulnerable to many outside predators.
The color of the shell differs between adults and hatchlings. For adults, the carapace color is an olive-brown to black color or very dark green and the plastron is a yellowish-white color (Green Sea Turtle Fact sheet, 4). Hatchlings have a dark brown or nearly black carapace color with a white plastron and white flipper margins (Fact Sheet: Green Sea turtle, 1). The turtles are actually not named after the color of their shell as many might be led to believe but are named for the color of their body fat under their shells. There are many distinguishing features that these turtles possess that make them unique to the other sea turtles. Their heads are small and blunt with a single set of prefrontal scales, a serrated jaw as well as facial markings that are unique to each individual turtle. These facial markings are like fingerprints, no turtles have the same marking making them specific to the individual turtle (Sea Turtle Restoration Project, 8). These markings are used sometimes to help scientists identify which turtle is which. As well as the facial markings, the single pair of prefrontal scales is unique to these turtles. These scales, which are located in front of the turtlesŐ eyes, come in double pairs on other sea turtles; the Green Sea Turtle is the only turtle with a single pair of these scales (Sea turtle survival leage, 1). Another distinguishing factor between the Green Sea turtle and other sea turtles is that they are the largest of the sea turtles. They can reach up to four feet in length and weigh up to five hundred pounds; the most common length and weight is three feet and two hundred and fifty pounds (Green Sea Turtle fact sheet, 4). Lastly, these turtles are very versatile in that they are able to breathe through their lungs when they are on land (essential for nesting periods) and are able to breathe through their skin when they are in the water.
The green Sea Turtle is very adapted to itŐs aquatic environment. Due to the fact that these turtles are ectodermic, it causes them to have a slow metabolic rate. This allows them to stay under water for long periods of time, up to five hours. During these long dives the heartbeat slows down in order to conserve oxygen; it sometimes will slow to nine minutes between heartbeats. When the metabolism is this slow, blood is shunted away from tissues tolerant of low oxygen level and redirected towards the heart, brain, and central nervous system. One other interesting thing about the Green sea turtlesŐ metabolism is that it allows for the turtles to attain a sufficient amount of fresh water from metabolizing seawater (they also acquire freshwater from their diet). Another adaptation that these sea turtles possess is that they have a salt gland to rid their bodies of any excess salt that they may acquire. This gland also serves as method for keeping the sand out of the femalesŐ eyes when they go up onto the beach to lay their eggs. All of these adaptations have allowed these Green Sea Turtles to survive for thousands years the only drawback of these adaptations is that it makes the turtles very vulnerable on land.
The Green Sea TurtleŐs diet changes drastically from when itŐs young to when it becomes an adult. The younger turtleŐs (less then eight inches in length) diet consists of jellyfish, algae, shrimp and crustaceans where as Adult turtleŐs (larger than 8 inches) are strictly herbivores eating sea grass and mangrove leaves. The Green Sea Turtle is the only turtle that is strictly herbivorous as an adult; all other adult sea turtles are carnivores (Green Sea turtle, 5). When both adult and young Green Sea turtles eat, they stay underwater for about five to ten minutes at a time. Besides eating, there are other behavioral habits that the sea turtles have. When the turtle is resting, they tend to stay underwater for about two and a half hours; young sea turtles usually sleep on the surface of the water. They are also very strong swimmers with a cruising speed of .9-1.4 mph. Humans have caused some changes in the Green Sea TurtleŐs behavior. For example they cause the turtle to steer away from nesting beaches due to noise pollution, light pollution and other irritants. This has a major effect on the species as a whole because the females cannot further the species by laying their eggs.
Reproduction for Green Sea Turtles is a very important but dangerous process. Scientists are not sure when these sea turtles reach sexual maturity but they believe that it is between twenty to fifty years. They base this estimate on the size of laying femalesŐ shells (about thirty-five inches long). Mating season lasts from October through February but does not occur every year but on cycles of three years. The main reason being due to the fact that the feeding areas and nesting grounds are far apart and it is a long and dangerous journey to get back and fourth. Common nesting grounds that the Green Sea Turtles go to during mating season are Tortuguero beach in Costa Rica, Aves Island in the Caribbean and Ascension Island in the mid-Atlantic (Fact sheet: Green Sea turtle, 1). The actual mating process occurs on the surface of the water and it takes a few nights before the female can go on shore and lay her eggs. When its time to begin laying her eggs, the female will climb up the beach and will then dig a hole with her front limbs to lay her eggs in. Once the hole is dug, the female will then lay eighty to two hundred eggs. These eggs represent one clutch that the female turtle will lay. The females typically lay one to seven clutches in twelve to fourteen day intervals during the mating season. After laying her eggs the female returns to the water and has no further interaction with the eggs.
Green Sea Turtle eggs go through an incubation period of two to three months before they hatch. The environment during this time has a substantial effect on the development of the eggs. ŇAt 82 degrees Fahrenheit, all of the hatchlings will be male, whereas at 90 degrees Fahrenheit all of the hatchlings will be female (EBSCO, 111)Ó. When the eggs hatch, the hatchlings are about 1.75 to 2.375 inches long and weight about .9 ounces (Sea Turtle Restoration project, 5). It is known that when the hatchlings reach sexual maturity they return to the same beach that they themselves were hatched at, although how they remember where they were hatched still remains a mystery to scientists.
There are many natural threats that make it difficult for hatchlings and adults to survive. When the females go onto the beach in order to lay their eggs they are threatened often times by dogs and humans and in many Mediterranean areas, tigers and jaguars. Once the eggs hatch, the hatchlings are at their most vulnerable state that they will ever be in. They are threatened by birds of prey, ghost crabs and even raccoons. Once in the open water they are at risk of being prey to tiger sharks and large fish. The adult sea turtles, although at less of a risk than the hatchlings, are still threatened by large tiger sharks.
Humans have the largest impact on the Green Sea Turtle species and are causing the species to become endangered. In the 1970Ős this species, which has survived on earth for thousands of years, was thought to only have 100,000-400,000 individuals remaining within the whole population (Green Sea Turtle Fact Sheet, 4). One large contribution to the endangerment of the turtle species is the food production industry. In the 1950Ős especially, there was a high demand for these Green Sea Turtles for their meat, flesh and oils. The meat tasted good and was a great source of protein and since the turtles were easy to catch, eating their meat seemed like a feasible option. Besides the food products that the turtles had to offer, they were also in high demand for their shells in order to make jewelry and make leather out of their skin and oils. The demand was very high, Ňfor example in just one year 15,ooo Green Sea Turtles were imported into England in the late 1800s (Sea turtle Restoration Project,). There was also a high demand for their eggs which also served as a good source of protein; the eggs were commercially exploited, causing a drastic change in the total number of the species.
Today, pollution is a huge negative influence on the Green Sea Turtle species. Often times garbage is left on the beach from beach goers and the garbage attracts predators such as raccoon and other land animals that would otherwise not be on the beach. The land predators threaten the females laying their eggs, an unnecessary threat. Also, Sargassum Weed, where some green sea turtles spend the early part of their lifecycle accumulates oil, Styrofoam and other plastics causing the turtles to find a new feeding ground or worse, they eat the pollution. Introduction of exotic vegetation is also a human cause resulting in the turtles to find a new nesting area. This vegetation inhibits nesting areas by forming barriers and dense root mats (hard for them to dig through). The pollution on the beach also makes it hard for the females to climb up to the beach and often times they will turn around and go right back out to sea without laying their eggs. Noise and light pollution are also large factors in causing the females to steer away from her nesting area and not lay her eggs. The way that noise and light pollution works is that if too many lights are on during the night at a nesting ground (parking lot lights, etc) then it confuses the female into thinking that it is daytime and she will not lay her eggs and the if there is a lot of noise then she will also leave.
New Development and boating cause harm to the Green sea Turtle species as well. There is a high demand today for living right on the beach. Besides the noise and light pollution that this creates the new development actually changes the landscape and often times makes nesting grounds smaller and more dangerous for the females to lay their eggs. Boating accidence also cause many problems for the turtles. Examples include oil spills caused by sinking tankers or even if a turtle encounters a boat motor. These turtles are also many times caught in shrimp nets and tuna or even swordfish longlines.
Despite these negative human interactions, more is currently being done to try and help the species. For example in 1980 the Stranding Network, with the help of the New York State Department of Environmental Conservation, Nation Marine Fishing Service, and the Riverhead Foundation, developed a hotline for people to call to report stranded and dead Green Sea Turtles. There is a large effort to educate the public of the dangers that these turtles face as well. There are educators at aquariums and marine camps, as well as educational shows on such channels as the discovery channel that all teach conservation about these turtles. This education helps the public to appreciate these creatures more and teaches how they can make a difference to help conserve the Green Sea turtle species. Specific conservation measures have been taken as well. One of these new changes is the use of TED. TED is a device located on new regulation shrimp trawling nets issued by the U.S Fish and Wildlife Service. The purpose of this new net is to allow the survival of any turtle (or large marine life) that swims into it by having an excluder device (TED) attached to the net. This excluder allows the turtles to swim out of the net without any harm. There are also many wildlife refugees that help to conserve the living area of these turtles as well as help revive any standing or injured turtles. One of the things that they do to help conserve is place screens over the turtlesŐ nests to prevent any predators from getting to the eggs. Lastly, there are many Ňadopt-a-turtleÓ foundations that allow the public to personally help save a specific turtle in need. It gets the public involved and hopefully will motivate them to be better about their bad habits in their everyday lives that could cause harm to the turtles.
Despite all of the conservation efforts, there is still more that is needed to be done. One theory about how the conservation process of the Green Sea Turtles is not showing longterm results is that the conversation efforts are awaiting the extinction of the species based on only the fact that there are so few turtles. They believe that the only solution that will help the turtles survive is if the numbers of the turtle population are increased. In all reality these people may not actually be addressing the problem of the actual threats such as pollutions, human interaction, etc (Frazer, 1992). ŇBasically the turtles that are bred in captivity solely for the purpose of increasing the number of sea turtles are being let out into a degraded environment in which their parents have already demonstrated that they cannot flourish in (Frazer, 1992)Ó. The best approach to solving the problem of the Green Sea TurtlesŐ endangerment would be to directly resolve the particular problems encountered by sea turtles without removing them from their natural habitat (Frazer, 1992). One such example of these efforts is the use of the TED. All in all it is important that the public persists in itŐs efforts for solving the sea turtlesŐ problems and commit to the long term goals of keeping the turtles safe.



References:

"Fact Sheet: Green Sea Turtle." Caribbean Conservation Corporation and Sea Turtle Survival League. 6 Apr. 2007 .

Frazer, Nat B. "Sea Turtle Conservation and Halfway Technology." 6. June 1992.

"Green Sea Turtle." 6 Apr. 2007 .

"Green Sea Turtle Fact Sheet." New York State Department of Environmental conservation. 6 Apr. 2007 .

"Green Sea Turtle." Sea Turtle Restoration Project. Mar. 2003 .

"Green Turtle." Encyclopedia of Animals. EBSCO. 16 Apr. 2007.

"Sea Turtle Rehabilitation and Hatchling Program." 6 Apr. 2007 .

"Sea Turtles." Sea World. 6 Apr. 2007 .

"The Turtle Hospital." 6 Apr. 2007 .


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