provided to The Santiva Chronicle
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 of Mexico.
Since last month, 5,812 hatchlings have emerged on the islands (5,772 loggerheads, 40 leatherbacks), and 793 total nests have been laid this season (790 loggerheads, two green turtles, one leatherback).
With so many hatchlings trying to find their way to sea, artificial lighting poses a significant threat. Sanibel Captiva Conservation Foundation Sea Turtle Biologist Jack Brzoza explains why artificial lights are 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 beach areas with higher levels of artificial light.
Historically, suitable nesting beaches are often backed by vegetation and dune structures, which create a shadowed, darker horizon. Once they emerge from the ocean, nesting sea turtles may continue to crawl inland along the sand toward 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, determined by factors like moonlight and cloud cover at night.
For nesting females, artificial lights may deter them from coming ashore or crawling further up a beach to nest. It could be due to the seaward direction appearing darker than artificial lighting from an inland source.
Suppose a female fails to nest after multiple attempts. In that case, 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.
These photos show disorientation tracks from a female sea turtle attempting to nest. SCCF photo
Artificial lighting can create a miscue for hatchlings and draw them landward, away from the ocean.
Hatchlings that are disoriented and head toward these lights may never reach the water. They can overexert themselves as they crawl further away from the ocean and 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 onto the beach. Exterior lights should be sea turtle-friendly devices and bulbs.
Sea turtle-friendly lights often produce a long red or amber/orange wavelength. Red light emits a narrow portion of the visible light spectrum, and it does not disrupt sea turtles as much.
Red light greatly dampens the effect of artificial light and is less disruptive to the natural light field, allowing 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 the moon provides is enough to see comfortably. 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.
Stranded turtles or issues related to nests, lighting, beach furniture, or holes in the sand can be reported to the Sanibel Captiva Conservation Foundation Sea Turtle Hotline at 978-728-3663.
Lighting violations can also be reported to the Sanibel Police Department by calling the non-emergency phone number, 239-472-3211, or Sanibel Code Enforcement, 239-472-4136, or Sanibel Natural Resources, 239-472-3700.
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