Baby Sea Turtles Hindered and Helped by LightsBy Sarah 2014/9/24
Have the lights of human’s in Florida led tens of thousands of baby sea turtles to their death? The sad answer is “yes,” but now work is being done to reverse what was a devastating trend.
The issue here is that the U.S. State of Florida is home to ninety percent of all sea turtle nesting sites in the country, and humans love the beaches just as much as the turtles. Human encroachment has meant that the light coming off of roads, buildings and homes shines down upon the beaches. This is a huge problem if you are a baby sea turtle, which hatches in complete darkness in a nest buried under the sand. The newborn turtles dig their way out onto the beach, where they are supposed orient themselves to crawl to the ocean. However, baby turtles primarily navigate by using the light of the stars and moon reflected on the open water. Sadly, the lights of human civilization are much brighter, and the turtles get confused. Many of them start crawling further inland instead of towards the sea. They become lost and dehydrated; they get eaten by predators and hit by cars.
Even though light has historically been the problem, it can also be the solution. There are new LED lights slowing being installed in areas near nesting beaches that are difficult for the turtles to see. According to an interview with Scientific American, Sea Turtle Conservancy representatives explain the impact of the new lights. Specialist Karen Shudes explains, “There are several rules of turtle lighting, keep the light as low to the ground as possible, keep the lumens as low as possible, keep the light shielded and keep the wavelength long.” LED lights that fit these requirements have been installed by the Conservancy in more that eighty high-risk areas. Florida state and county ordinances now require turtle friendly lighting around beaches during nesting season.
The reason this type of LED works is because light exists on a spectrum, and animals see parts of the spectrum differently depending on their eyes. In humans, the long wavelengths that are difficult for the baby turtles to detect look red or orange. Some might think that the orangey glow of an older sodium halide fixture would be enough, but “Even though a bud or sodium light might look yellow to you or me,” says Sea Turtle Conservancy Director David Godfrey, “if you looked at it through a spectroscope, you would see the full spectrum of light. It may peak in the yellow region, but there’s plenty of light throughout the spectrum. So those lights were still attracting turtles because they were sensitive to those different wavelengths.”
As it happens, these turtle-friendly LEDs are seventy percent more efficient than incandescent bulbs, which makes these new lights energy-friendly too.
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