Copy of Sea Turtles: The Moths of the Ocean
Published on Mar 15, 2016
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PRESENTATION OUTLINE
Imagine, if you will, a world of no darkness, one that has embraced mankind's desire to make the world more technologically fit. A world, consumed by lights of man's own innovation and accomplishments, is imminent in our desire to vanquish darkness. However, we do not understand the consequences that lie ahead with this innovation. The light that we so desire will soon destroy what we have once beloved. The animals of the world are threatened by our need to light up the world. The sea turtle is patient zero of this widespread epidemic of technology
and artificial lighting.
Imagine Sitting in a Dark Movie Theater. The light of the projector on the screen is clear, until the lights suddenly blare. While the movie is still playing, it isn't visible anymore, as there is too much external light.
Photo by Heritage Vancouver
What Is Light Pollution?
- Light Pollution is the emittance of blue light in the atmosphere, causing the night sky to become brighter
- While a portion of the blue light is a natural occurrence (light refracted from the sun), a large chunk is caused by artificial light sources, such as LED light bulbs.
- When light is emitted, it is very dense. As it nears the various gas molecules in the atmosphere, it begins to granulate (spread), and it becomes less dense. Blue is one of the least dense colors on the color spectrum, so as the blue light is absorbed, the gas molecules spread along the atmosphere. This causes the sky to be blue.
- However, with artificial light sources, too much blue light is emitted, and the sky becomes lighter and lighter as night comes.
- That is why large urban areas, such as Paris, do not become dark until late at night.
Photo by r.nial.bradshaw
Untitled Slide
Photo by Werner Kunz
How Does Light Pollution Affect Humans?
- Sure, it may be nicer to have more light, but too much can have some disastrous effects.
- For one, blue light suppresses melatonin production. Melatonin is the sleep hormone secreted by the pineal gland in the brain. Without it, we will have great difficulty falling asleep. Melatonin is only activated in the dark; the increasing amount of blue light in the atmosphere causes the night sky to become brighter.
- This leads to sleep deprivation, as well as sleep-induced disorders such as circadian rhythm sleep disorder (A misalignment with the endogenous sleep cycle and the circadian rhythm, usually caused by a irregular sleep-wake cycle) and insomnia.
- "Darkness is as essential to our biological welfare, to our internal clockwork, to light itself. The regular oscillation of waking and sleep in our lives -- one of our circadian rhythms -- is nothing less than a biological expression of the regular oscillation of light on Earth. So fundamental are these rhythms to our being that altering then is like altering gravity."
Photo by kaibara87
How Does Light Pollution Affects Animals?
- " 'Over millions of years, animals have come to depend on seasonal, monthly, and daily patterns of light and dark,' says Longcore. 'Only recently have humans lit up the night on a global scale.' "
- This quote accurately describes the impact light pollution has had on animals that tend to sojourn near urban areas (on beaches and coasts).
- Through millions of years, animals have depended on light to determine where to sleep, where to go, and what to do.
- Animals that live near large urban areas depend on the moon for migratory or navigation purposes.
- However, light pollution has made the night sky brighter, and the moon is practically invisible to the eyes of the animals who depend on it most. The excessive amount of external artificial light has caused confusion and overall death to many marine and sky animals.
- Take for example the migratory bird. It depends on the moon and many other significant light sources for navigation and direction. However, external light sources confuse these animals, and they end up flying straight into large buildings that were not visible.
- Light pollution is impacting animals' perception of light, and they are not able to navigate, migrate, or do anything else.
Photo by davedehetre
LIGHT POLLUTION AND THE SEA TURTLE
Photo by laszlo-photo
"Nesting sea turtles, which show a natural predisposition for dark beaches, find fewer and fewer of them to nest on. Their hatchlings,me hick gravitate towards the brighter, more reflective sea horizon, find themselves confused by artificial lighting found behind the beach. In Florida alone, hatchling losses range in the hundreds to thousands."
To Verify This Statement, Here Are the Results of an Experiment Conducted in Australia Comparing the Abundance of Sea Turtles in Areas With Large Amounts of Artificial Light and Areas With Little or None Artificial Light.
Photo by Iqbal Osman1
"We found no evidence of impaired hatchling orientation, and observed very low levels of light at Peak Island. However, at Curtis Island, hatchlings displayed reduced sea-finding ability, with light horizons from the direction of nearby industry significantly brighter than from other directions. The sea-finding disruption observed at Curtis Island was less pronounced in the presence of moonlight. Conclusions. The reduced sea-finding ability of Curtis Island hatchlings was likely due to both altered light horizons from nearby industry, as well as beach topography."
What do these results imply? Peak Island, which was the more rural area (or one with less artificial light), showed no signs of impaired hatchling orientation, meaning that they could navigate the sea and go towards the moon. However, at Curtis Island, which was the more urban area, displayed signs of disturbed hatchling orientation, due to the bright lights of the nearby industry. The nearby industry, along with beach topography, had altered the light of the horizon, and hatchlings could not as easily (or not at all) have swam toward the sea. This is called phototaxis positive. It is a false perception of the environment in relation to light. Phototaxis positive is when animals' perception of light is boggled by other external sources of light. The suprachiasmatic nucleus, an area of the brain associated with light intensity, is the area that helps notify the brain that it is day or night. With the case of light pollution, night turns into day, and the moon (the source of light truly sensed at night) is just a blurb in the sky. In the case of the sea turtle, hatchlings could not tell where to go, due to an abundance of external artificial light sources.
Why Should We Care About Sea Turtles?
So What!?
Sea turtles have been a staple in understanding the history of life on earth, as they are theorized to have lived on earth for the past 150 million years. Sea turtles allow us to understand life a million years in the making; how organisms lived and behaved in the past. The sea turtle, however, has been endangered for quite some time, due to egg harvesting, oil spills, netting, fishing, light pollution, etc.
Photo by Daikrieg
NESTING
"Some females nest every two to three years; some may nest more than once on the same beach in a season; and some visit more than one nesting beach in a season." With the number of nesting grounds unavailable, females find it more and more difficult to nest. In doing so, most females nest every 2 to 3 years, unless they may nest on the same beach. Even then, most of the hatchlings do not even make it to the shore, due to an abundance of artificial light sources.
Photo by heatheronhertravels
ENDANGER
THE SEA TURTLE
Over the past century, the sea turtle population has declined by 60%, due to egg consumption, netting, and habitat loss. The habitat loss contributes to the decrease of newborn sea turtles, as the increased amount of light pollution diminishes the amount of suitable nesting grounds. Not only is there a decreased amount of suitable nesting grounds, "Most sea turtles live approximately 15 to 20 years and may live to be 80 years old." Not only is the life expectancy of sea turtles 15 to 20 years - most sea turtles only nest every 2 to 3 years; the average sea turtle can expect to nest 7 or 8 times in its lifetime. Even though the average sea turtle would nest 7 to 8 times, most of the hatchlings would die, mostly due to light pollution. Due to this factor, only about 5 to 10 of the 110 eggs laid in a nest would survive and hatch, or the entire nest would be destroyed. That means that 35 to 40 (or 70 to 80) of the eggs laid by a sea turtle in its lifetime would survive. Even with that factor, a large amount of those sea turtles would die.
Photo by Vernon Barford School Library
Untitled Slide
- Light pollution is impacting the sea turtle's perception of light and the night sky
- Light Pollution is decreasing the amount of nesting grounds available
- Even though light pollution is not the only factor to the endangering of the sea turtle, it is what impacts the amount of sea turtles
A CALL TO ACTION
- Create enclosed nesting grounds for sea turtles on beaches
- Use more fluorescent light bulbs
- Create sea turtle reservations
- Create policies for the netting of sea turtles and consumption of eggs/nest destruction
- Create barriers along roads and highways directly next to beaches
CITATIONS
- >Guynap, Sharon. "Lights Out."
- Kamrowski, Ruth, Col Limpus, Kellie Pendoley, and Hamann Mark. "Influence of Industrial Light Pollution on the Sea-finding Behaviour of Flatback Turtle Hatchlings.&
- ">Klinkenborg, Verlyn. "Our Vanishing Night." Ebscohost
- -">Price, Sean. "Light Pollution." Sirs Discoverer
