This post was written by Keith Dawson for UBM Tech’s community Web site All LED Lighting, sponsored by Philips Lumileds. It is archived here for informational purposes only because the All LED Lighting site may go dark at any time. This material is Copyright 2013-2015 by UBM Americas.


Turtle-Centric Lighting

Florida seacoast residents, spurred by state and local laws, are installing specialized LED lighting so as not to interfere with the migration of threatened and endangered baby sea turtles.

We had a quick look at Florida's turtles last June, after Lighting Science Group promoted their turtle-friendly lighting at Lightfair. Now a blog post in Scientific American, at the beginning of the annual sea-turtle nesting season, brings a new spotlight on this expanding story.

Florida is home to five species of sea turtles (out of six worldwide), and 90% of the turtles in the US. Four of those species are threatened and one is endangered, under the terms of the Endangered Species Act. The state of Florida, its coastal counties, and municipalities along the coast have all enacted laws and regulations protecting sea turtles in ways that go beyond the federal law.

The largest threat that human civilization poses to sea turtles, once it became illegal to harm or molest them directly, comes from lighting. Baby turtles hatch from eggs laid on beaches and need to get to the sea quickly. In the absence of man, they are guided there by moonlight and starlight reflecting off the water. In populated areas, artificial light draws the baby turtles like moths to a flame, where they are picked off by predators, run over by vehicles, or die of dehydration.

Click for a larger version.
(Source: Florida's Fish and Wildlife Conservation Commission)

Turtles' vision is in a higher frequency range than that of humans. It extends from about 580 nm up into the ultraviolet, peaking in the blue-green. So light at 590 nm and below -- amber, orange, red -- is invisible to the turtles.

Until this science was well understood, early attempts at providing turtle-friendly light weren't successful, because a sodium light (for example) that looks amber to human eyes still packs energy in the shorter wavelengths. The ability to tune LEDs' spectra to pretty much any desired curve makes them ideal as a source for turtle-safe lights.

Florida's Fish and Wildlife Conservation Commission oversees preservation efforts at the state level. The commission long ago drafted model regulations for counties and municipalities to adopt. A summary with links is here. One of the regulated areas is lighting. The illustration shows the 17 out of 31 coastal counties that had enacted such regulations as of last summer. Here is a sample, the lighting-related rules for Flagler County.

The rules state that lighting visible from beach areas must be of low enough frequency so as not to attract the turtles, and additionally it must be cut off so as not to shine directly on the beach wherever possible.

Turtle-safe lighting products and supplies are available at many outlets in Florida. Here is a sample from the web.

Deepwater Horizon connection
Many seacoast communities have now been more or less fully retrofitted with turtle-safe lighting. The state is able to offer matching grants to offset some of the cost to landowners by tapping a fund that originated in the massive Deepwater Horizon oil spill in 2010. The spill killed an estimated 100,000 sea turtles, and part of the reparation and penally money British Petroleum paid is going toward the installation of LED lighting around the Gulf and Atlantic coasts. Still, tens of thousands of hatchlings each year walk toward civilization instead of toward the ocean. Much work remains to be done.

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