Stay in the know about wildlife, water quality, and ecosystems on Sanibel and Captiva Islands and in Southwest Florida
Lights Out for Sea Turtles
It’s sea turtle hatching season on Sanibel and Captiva! While adult turtles are laying their final nests of the year, many nests are beginning to hatch, and thousands of hatchlings are starting their journey out into the Gulf.
Since last month, 5,812 hatchlings have emerged on the islands (5,772 loggerhead and 40 leatherback), and a total of 793 nests have been laid this season (790 loggerhead, 2 green turtle, 1 leatherback).
With so many hatchlings trying to find their way to sea, artificial lighting poses a significant threat. SCCF Sea Turtle Biologist Jack Brzoza explains below.
Call the SCCF Sea Turtle Hotline at 978-728-3663 to report stranded turtles or issues related to nests, lighting, beach furniture, or holes on the beach. Lighting violations can also be reported to the Sanibel Police Department at 239-472-3111, Sanibel Code Enforcement 239-472-4136, or Sanibel Natural Resources at 239-472-3700.
Why Are Artificial Lights a Threat to Sea Turtles?
While adult sea turtle females find their way to their natal beaches to lay eggs using magnetic signatures from Earth’s electromagnetic field, multiple studies have suggested that fewer nests are laid in areas of the beach where there are higher levels of artificial lights.
Historically, suitable nesting beaches are often backed by vegetation and dune structures, which create a shadowed, darker horizon. Once emerged from the ocean, nesting sea turtles may continue to crawl inland along the sand in the direction of this dark horizon.
For hatchlings, it’s a reversal of this concept. Sea turtle hatchlings emerge from the nest at night, and one of their cues to finding the ocean revolves around orienting to the brightest point on the horizon, which would naturally lead them in the seaward direction.
What Happens When Artificial Lights are Introduced?
Artificial lights disrupt an environment’s natural lighting, which at night are determined by factors like moonlight and cloud cover.
For nesting females, the presence of artificial lights may deter them from coming ashore or crawling further up a beach to nest. This could be due to the seaward direction now appearing darker than artificial lighting from an inland source. If a female fails to nest after multiple attempts, she will eventually resort to a best-case scenario of nesting in a sub-optimal area or, at worst, depositing the eggs in the ocean where they will not survive.
For hatchlings, artificial lighting can create a miscue and draw them landward, away from the ocean.
Hatchlings that are disoriented and head toward these lights may never make it to the water. They can end up overexerting themselves crawling away from the ocean and can end up in dangerous places such as parking lots, roadways, and pools. In addition, the longer the hatchlings are on land, the more susceptible they are to terrestrial predators.
What Can You Do to Help?
For those in beachfront residences, turn off lights at night or close blinds on windows so that interior light does not emanate out onto the beach. Exterior lights should be sea turtle-friendly devices and bulbs.
Sea turtle-friendly lights often produce a long wavelength — red or amber/orange. Red light emits a narrow portion of the visible light spectrum, and sea turtles are not as disrupted by them. This greatly dampens the effect of the artificial light and is less disruptive to the natural light field, allowing for turtles to navigate by the appropriate, natural cues.
Also refrain from using flashlights or cell phone lights while on the beach in the dark. Many nights, the natural light provided by the moon is enough to comfortably see. If you would like the assistance of an artificial light, such as a phone or flashlight, use a sea turtle-friendly red light or red filter.