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Out of the Light and Into the Darkness: Managing the Impacts of Artificial Light on Sea Turtles

Credit: Kevin E. Geraghty

I will never forget the first time I saw a sea turtle hatchling open its eyes to the world. I was working as a biologist performing sea turtle nesting surveys on Hutchinson Island in Florida and the time had come for the first nests to start hatching. I was lucky enough to arrive while some hatchlings were still emerging from the sand in the early morning hours. I felt an immediate connection and an overwhelming desire to protect these tiny, vulnerable creatures at my feet, struggling to extricate themselves from the sand to reach the sea. It was one of the most magical moments I have ever witnessed. Unfortunately, that magical moment was immediately followed by extreme panic when I noticed numerous, delicate flipper tracks in the sand that trailed off from the nest in the opposite direction of the water and over the dune. I began searching frantically for their whereabouts, knowing that they may not have much time to live after sunrise if I didn’t find them quickly. My panic was soon replaced by profound grief when I came upon numerous small, crushed bodies of turtle hatchlings on the asphalt of Highway A1A. They had been lured away from the sea and into the road by bright streetlights. I was too late…

credit: Karen Shudes

Unfortunately, my experience is by no means an isolated incident. This scenario likely repeats itself somewhere in Florida every single day during the nest hatching season; and year after year; resulting in the deaths of hundreds of thousands of newborn sea turtle hatchlings and occasionally adult turtles as well.

Managing the problem of artificial light pollution is particularly important in Florida, where approximately 90% of all sea turtle nesting in the United States takes place. Because only approximately 1 in 1000 hatchlings survive to adulthood (which takes anywhere from 20-30 years), the loss of hatchlings caused by poorly managed light represents a major obstacle to the recovery of U.S. turtle populations.

Dawn Witherington

Artificial lighting affects both nesting adult females and newborn hatchlings in different ways. Nesting adult turtles once had no trouble finding a quiet, dark beach on which to nest, but now they must share the beach with millions of tourists, coastal residents, and businesses. Bright lights from these developments can illuminate the beach and discourage female turtles from coming ashore to nest or cause them to select less-than-optimal nesting sites, thus reducing the hatchling survival rate. Additionally, it can also cause nesting females to become disoriented once they are on the beach and prevent them from finding their way back to the water. Females that become disoriented on the beach waste energy wandering around and can become trapped in places they don’t belong—like behind fencing and in swimming pools. Occasionally, turtles will find their way onto major roadways where they are struck and killed by cars.

credit: Dawn Witherington

Artificial lights cause problems for hatchlings as they emerge from their nests and instinctively crawl toward the brightest direction, which would be towards the ocean on a dark beach. Bright artificial lights attract and disorient hatchlings, causing them to crawl inland and away from the ocean or to wander aimlessly on the beach, all the while burning up vital stored energy that is crucial for survival if they do ever manage to reach the sea. Disoriented hatchlings often die from dehydration, exhaustion, terrestrial predation and even passing cars. If they make it to the ocean, they have a lower chance of survival due to energy loss, making it harder to reach important off-shore habitats and increasing their susceptibility to countless marine predators.

The good news is that light pollution is manageable. Light does not linger in the environment like other polluting substances. As technology advances, there are numerous solutions to light the night without impacting ecologically sensitive habitats, disrupting ecosystems, threatening astronomy and wasting energy.

Condos before light retrofit 

Condos after light retrofit

Sea Turtle Conservancy (STC) has been working aggressively since 2010 to correct problematic artificial lighting in coastal areas of Florida. STC’s initiatives, which involve working with private beachfront property owners to retrofit problem lights using the latest sea turtle-friendly technologies, have seen major successes in managing the effect of problematic lights at properties that had previously been responsible for the disorientation of nesting adult females and newborn hatchlings each year. STC has completed over 80 lighting retrofit projects in Florida’s coastal communities through funding provided by the National Fish and Wildlife Foundation, as well as supporting grants from other organizations and foundations. STC’s lighting retrofit work has been immensely successful and has achieved significant decreases in sea turtle disorientations near retrofitted properties. Thousands of hatchling sea turtles have reached the sea that otherwise would have been disoriented by lights. This huge success has paved the way for additional funding to continue the crucial work of ensuring threatened and endangered sea turtle hatchlings make it to the ocean.

Hotel before light retrofit

Hotel after light retrofit