Dark Sky Lighting can range from Old World-style lanterns (above) to contemporary fixtures (below).
Photos provided
By Cheryl Blackerby
In the past two years, a deadly enemy of sea turtles has emerged: sky glow.
The low cloud cover in summer and the rise in residents in winter create a brilliant orange nighttime smog of light over inland cities that disorients nesting sea turtles, even though the lights directly on the beach have been turned down or off.
Instead of finding their way to the ocean, guided by reflected starlight and moonlight on the water, they head toward the bright lights of the city and the city glow streaming between beachside condos.
Experts are worried about this year’s hatchlings that started appearing in June, and will continue through the end of October. Last year, Boca Raton had 74 sea turtle nests, each averaging about 85 hatchlings, that were disoriented because of “sky glow” and many didn’t find their way to the ocean.
“They scattered on the beach, wandering. Thirty percent are not making it to the water,” said Kirt Rusenko, marine conservationist at Gumbo Limbo Nature Center in Boca Raton. “This is lethal. They’re usually picked up by a fox or raccoon or they just simply run out of energy and when the sun comes up it cooks them.”
The disorientation has greatly worsened recently, he said.
“Prior to three years ago, the hatchlings would be disoriented by night glow but would find their way to water,” he said. “Starting two years ago, they didn’t find their way to water. The light is more of a lethality, and it’s now starting to kill hatchlings. Scientists estimate that sky glow doubles every 11 to 12 years.”
The best course of action to combat sky glow, he said, is to turn off lights or use full-cutoff light fixtures that shine on the ground and not into the sky.
Lighting companies have started selling “Dark Sky” light fixtures approved by the International Dark-Sky Association that are sold in Lowe’s, Home Depot and online.
The products vary from Old World-style Mediterranean lanterns to modern ceramic sconces.
Boca Raton, Palm Beach and other beach municipalities have installed full-cutoff streetlights and lights at city buildings that project light fully on the ground and not into the sky.
Companies have been urged to turn off lights in office buildings at night.
City residents are becoming more aware of the problem and are asking the staff at Gumbo Limbo, who advise parks and cities about Dark Sky lighting, questions about light fixtures. Rusenko tells them that the lights have practical benefits as well as saving sea turtles.
“You usually save roughly 60 percent on the electric bill when you use these fixtures. And condo members say they notice the decks and pools are brighter, making them safer, even though the buildings are darker,” he said.
In Florida, excessive lighting disrupts the biological cycles of wildlife. “Light pollution” can disorient birds, chase fish away from the shoreline, and interfere with the mating habits of frogs.
The Council of Science and Public Health reports studies that show nighttime artificial lighting adversely affects humans, too. It disrupts circadian biological rhythms that can increase cancer risks and some chronic diseases, and even contribute to obesity.
If full-cutoff lighting were used, he said, less money would be wasted by governments, businesses and homeowners, and more nocturnal animals would be able to live their lives as nature intended.
Rusenko is a founder and board member of the Palm Beach County chapter of the nonprofit International Dark-Sky Association (www.idasouthflorida.org), which meets monthly at the Florida Atlantic University observatory.
Meanwhile, nesting sea turtles seem to recognize the danger of sky glow, and are nesting in the nighttime shadows of high-rise condos. But that is not helping hatchlings that still can’t see the ocean.
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