Download Content- Endangered Species (Green Turtle)-01-09-13-21

Maddy Hale
SEA-DISC 2o, 5o, & 7o
November 29, 2012
Content- Endangered Species (Green Turtle)
Green Turtle the Lawn Mowers of the Ocean
The Green Sea Turtle is the only marine turtle that as an adult maintains an entirely
herbivore diet. This one of a kind species feeds primarily on a variety of different sea grasses,
including thalassia testudinum a sea grass that is high in fiber but has a low forage quality. A diet
high in fiber makes it so that the green turtle has a high digestive efficiency, an adaptation it
came by after years of consuming similar plant species. (Bjorndal, 1979) This cohesive
adaptation of species is known as coevolution. As both species thrive when one adapts the other
in turn must adapt to the change in the nature of its predator or prey, leaving no advantage to
either species.
Their specialist diet led to a very special adaptation, one that has created a special
ecological niche just for the Green Sea Turtle. The Green Sea Turtle is capable of digesting 90%
of the cellulose in its diet. Yet they only eat about 0.24 to .33 percent of their body weight a day!
(Bjorndal, 1979) Sea grass beds are necessary in sustaining biodiversity because they provide
nesting and breeding grounds for many species of fish and crustaceans. (Sea Turtle Conservancy,
2011) The adaptations the Green Sea Turtle has developed over the course of its existence have
made it an irreplaceable species and in the event of its extinction the world would be at a loss.
This foraging of sea grass helps a variety of different species living in the ocean. Fish,
crustaceans, and shell fish all depend upon the Green Sea Turtle to chew down the sea grass. The
Green Sea Turtle is often considered keystone species, making it that much more important. As
the Green Sea Turtle consumes the sea grass it is helping it thrive and remain it healthy, thus
resulting in the health of other ocean species. In fact, as the Green Sea Turtle eats the sea grass it
“encourages root growth which in turn increases the density of the grass bed” (Green Sea Turtle,
1985) This process is important for the sustainability of all ocean species. A decline in the
population of Green Sea Turtle would result in the decline in species whose survival depends
upon the health of regularly mowed sea grass beds. Without it the sea grass will remain uncut
and unhealthy, thus it will have no positive benefits for the other ocean species, and a significant
decline in biodiversity.
Green Sea Turtles: Nutrients for the Beach
The Green Sea Turtle has a very important role in beach ecosystems. What little
vegetation lies on the dunes of the beach is often a result of the sea turtles that nest there. The
Green Sea Turtle provides nutrient recycling for the beach ecosystems, without them the beach
would be barren and have no reliable food source for the other primary consumers. (Sea Turtle
Conservancy Bonaire, 2010) This gives the Green Sea Turtle instrumental value, its relationship
with its surrounding environment gives it an important role in its ecosystem.
When Green Sea Turtles release their eggs into the sand those that don’t hatch or make it
out alive decompose and become the vital nutrients in the beach ecosystem that provide
vegetation, what it needs to become stronger. Even the egg shells of the Green Sea Turtles that
hatched act as a powerful nutrient. “Along a 20 mile stretch of beach on the east coast of Florida
sea turtles lay over 150,000 lbs of eggs in the sand.” (Sea Turtle Conservancy, 2011) Many of
those sea turtles won’t hatch or successfully escape their nest and provide the beach ecosystem
with excessive amounts of nutrients. With good nutrients the dune vegetation grows strong roots
that help to stabilize the bank and prevent erosion. Without the Green Sea Turtle little plant
growth would not be strong enough to sustain the dunes and the beaches would wash away. (Sea
Turtle Conservancy Bonaire, 2010)
Natal Homing and its Effect on the Green Turtle
It seems only the most vulnerable and exquisite species have this characteristic. Natal
homing or natal philopatry is the characteristic many aquatic species have of returning to their
place of birth for their own mating rituals or giving birth. Let it be the stream in which they
hatched as it is for salmonids, or the beaches they were born on as it is form many species of sea
turtles.
Like many of its ancestors and cousins the green turtle is a species that always returns to
where it hatched in order to mate. This special adaptation makes it especially vulnerable to
extinction. If a pregnant Green Sea Turtle female returns to her place of birth and finds the beach
disturbed or destroyed by human activities she will not bury her eggs and instead will return to
the ocean and release her eggs out in the water.
“The female deposits between three and seven clutches per season at about 10 to 18 day
intervals. Average clutch sizes vary between 81 and 147 eggs that hatch usually within 48-72
days.” (Green Sea Turtle, 1985) Although many eggs are released into the sand not many survive
after that or into the later stages of life. Eggs are eaten by both humans and raccoons as well as
many other species. Those that do succeed in hatching often do not make it to the water’s edge
due to birds that prey on them. If they do survive, many don’t make it to reproductive age. In fact
at Tortuguero, Costa Rica, it was once estimated that survival from egg to sexually mature adult
was probably 0.1 percent. (Green Sea Turtle, 1985) Which is about Once the Green Sea Turtle
enters the water it is often met by many large fish waiting to eat them, still lowering their
survival rate.
Mutual Respect: The Symbiotic Relationship between the Green Sea Turtle and Hawaiian
Reef Fish
As an adult the Green Sea Turtle’s shell provides a habitat for a variety of types of plant
life on its back. This provides a healthy meal for many species of fish, since the Green Sea Turtle
will not eat the fish. Hawaiian Reef Fish in specific, has a symbiotic relationship that benefits
both the fish and the Green Sea Turtle. This symbiotic relationship is a form of mutualism. The
Green Sea Turtle gets a clean shell and the reef fish gets its food, without bringing harm to the
turtle. This fascinating relationship has developed over time and the mouth structures of certain
fish have adapted to clean different areas of the Green Sea Turtle.
Without this mutual respect, the fish must find a food source elsewhere, thus invading on
another species food source. It has been observed that the Green Sea Turtle develops a friendship
with many species of Hawaiian fish, including “Yellow Tang (Zebrasoma flavescens) and the
Golden Eye Surgeon Fish (Ctenochaetus strigosus). Occasionally, a parrot fish (Scarus dubius),
Pink Tailed Triggerfish (Melichthyus vidua), and Black Triggerfish (Melichthys niger), were
observed exhibiting cleaning behavior.” (Catellacci) Some of these species forage on exclusively
the turtle’s carapace. This amazing relationship is seen as some sort of ‘car wash.’ And is seen
throughout regions of the species, and is not a relationship exclusively for the Hawaiian Green
Sea Turtle.
This fascinating relationship provides income for tourist companies that provide ecotourism. Scuba divers and snorkelers travel by boat to atolls that provide tourists with a beautiful
experience that expands their belief in its existence value. Eco-tourists also look for a species
aesthetic value, the Green Sea Turtle is a beautiful species and to see it in its natural habitat is
always when it is at its most fascinating.
How bright is your flashlight?
Enjoy long walks on the beach? Do you do that night? Are you near the habitat of nesting
sea turtles? Your flashlight could be effecting the population of Green Sea Turtles. Somehow the
moon reflecting on the water after the turtles hatch acts as a homing device. This causes the
incredible species to follow the light until they hit the water’s edge and begin to swim. But with
big hotels with lights over their swimming pools and tourists and locals walking on the beach
with flashlights, the population of Green Sea Turtles is at stake. There is a solution; there are
special filters that alter the wave lengths of light allowing for the turtles to safely return to the
ocean without any human harm. But these devices are useless without your use of them. So next
time you are at the beach during nesting season, ask yourself do I need a flashlight?
Current Protection
The Green Sea Turtle has many populations all over the world, swimming in different
oceans and nesting on different continents. Each country may or may not have its own protection
plan for the Green Sea Turtle; in the U.S. and many of its territories they have established laws
that will protect the Green Sea Turtle as well as create wildlife sanctuaries.
In the UK the Cayman Turtle Farm is trying to become registered as a captive breeding
facility for Green Sea Turtles under the CITES treaty. Though this idea seems beneficial the
Cayman Turtle Farm breeds species from a different population of green turtles. Another issue is
the belief that there could be a possible introduction of diseases to the wild population of Green
Sea Turtles, thus having adverse impacts on the Caribbean gene pool of Green Sea Turtles. (Sea
Turtle Working Group of the Species Survival Network) The Cayman Turtle Farm is said to be a
conservation facility and tourist attraction and brings in many tourists each year, a common
tourist attraction put on by the Cayman Turtle Farm is its Annual Turtle Release. (Cayman Turtle
Farm, 2012) Though this carefree work maybe done properly the turtles it releases are often born
in captivity and may not survive out in the wild.
At Tortuga National Park in Costa Rica they have nest monitoring programs every year.
Villagers can apply for permits to take tourists on nightly tours of the beaches to watch the sea
turtles; this begins to get the community involved and brings money in for the locals. Tortuga
National Park also focuses “on the importance of educating Costa Ricans and visitors alike about
the various threats to sea turtle survival” (Sea Turtle Conservancy, 2011) “Some 50,000 tourists
visit Tortuguero annually to see nesting turtles and visit the tropical rainforests of Tortuguero
National Park.” (Sea Turtle Conservancy, 2011) The importance of the Green Sea Turtle is
apparent in merely the numbers of people who will pay to visit these incredible species in the
wild.
In American Samoa and Hawaii many vital nesting sites are within national parks or
wildlife refuges. American Samoa established a national marine sanctuary at Fagatele Bay as
well as creating a new national park with 3 units: Swofu, Central Ta’u, and Northern Tutuila.
Hawaii has a wildlife refuge at the Kure atoll and the NMFS (National Marine Fisheries Service)
Honolulu lab has its own recovery plan for Hawaiian sea turtles. (Pacific Sea Turtle Recovery
Team, 1998) Though these sanctuaries do much for the Green Sea Turtle populations without
sanctuaries and refuges in more populated areas of nesting grounds, not much of a difference will
be made.
What else should be done?
The importance of protecting this species is immense; it provides many ecological
services for its surrounding ecosystem and the other organisms living in it. One very important
principle is that you can save a species without saving its habitat. In order to fully protect the
Green Sea Turtle to its maximum extent it would become necessary for the government to
tighten its rains on poachers and the illegal trade of any products containing or created from the
Green Sea Turtle. But at the same time we need to begin to set aside beaches as wildlife refuges,
and begin to create oasis’s that are especially made just for the animal, with little or no human
contact what so ever. Often known as the buffer zone concept, the creation of national parks in
this manner would increase the protection and recovery of the Green Sea Turtle.
Environmental education and awareness is a large part of how you can begin to get
involved. Tell your friends and family about the issues the sea turtles face and what they can do
to help them. If you walk into a store with harsh lights on the beach, tell the person who works
there, if you find any sea turtle nesting sites there should be a phone number to call and they will
come and put up proper safety precautions for the nest, if you follow any of the links bellow they
will take you to a website that will allow you to adopt a sea turtle:
1) http://www.conserveturtles.org/adoptaturtle.php
2) http://www.seaturtle.org/tracking/adopt/
3) http://www.shopnwf.org/Adopt-a-Sea-Turtle/index.cat
4) https://salsa.democracyinaction.org/o/1723/p/salsa/donation/common/public/?donate_
page_KEY=5421
5) http://gifts.worldwildlife.org/gift-center/gifts/Species-Adoptions/SeaTurtle.aspx?sc=AWY1302WC922
The government should also begin to put in place regulations on light as to protect the
baby Green Sea Turtles from following the light and not reaching the water. By putting in
regulations on how far from the beach you can be with a harsh wavelength of light and how high
your lights wavelength can be. This kind of regulation would ensure the protection of this
astounding species. It’s important to spread the word, if you do everything in your power to help
the Green Sea Turtle, why wouldn’t someone else?
Green Sea Turtle Struggles to Survive
As a k-strategist the Green Sea Turtle struggles to reproduce enough to not go extinct.
Many things contribute to its endangerment like its migration patterns. With a variety of different
ecosystems needed for its survival the disruption of one can extinct the entire species. Other
factors contribute to the Green Sea Turtles struggle including large territory requirement, limited
food selection, low birth rate, specific nesting requirements, and interference with human
activities.
The Green Sea Turtle has a large territory requirement which greatens its possible
interference with human activities. As the human population rises the Green Sea Turtle becomes
more vulnerable to habitat destruction due to the need to feed or house the rising population. As
the population rises and the need for more food and shelter grows endangered species like the
Green Sea Turtle struggle to survive.
The Green Sea Turtle is a picky eater and only forages on sea grass beds; this diet
requires them to consume large amounts of sea grass in order to maintain a healthy diet. With
only a small selection of foods to choose from if some plant species go extinct along with it will
disappear the Green Sea Turtle. In some areas so much biodiversity has been lost they are
labeled as biodiversity hotspots or locations where biodiversity is dropping the fastest.