How Artificial Light Affects Sea Turtles
Sea turtles are among the oldest creatures on Earth, having survived the extinction event that wiped out the dinosaurs 65 million years ago. For over 100 million years, these remarkable animals have followed the same ancient rhythm: females crawl ashore to lay eggs on sandy beaches, and weeks later, tiny hatchlings emerge and make their way to the ocean, guided by the natural light of the moon and stars reflecting off the water.
But in the last few decades, a new threat has emerged that even 100 million years of evolution could not prepare them for — artificial light.
The Nesting Problem
Female sea turtles are extremely sensitive to light when selecting nesting sites. They prefer dark, quiet beaches away from human disturbance. Brightly lit coastlines deter females from coming ashore, forcing them to seek less suitable nesting sites or, in some cases, not nest at all. Studies have shown that beaches near artificial lighting have significantly fewer nesting events than comparable dark beaches.
In India, the Olive Ridley sea turtle — classified as Vulnerable by the IUCN — faces this threat along the eastern coast, particularly at Rushikulya in Odisha, one of the world's largest mass nesting sites (called an "arribada"). Coastal development, road lighting, shrimp processing units, and fishing village lights are encroaching on critical nesting habitat.
Hatchling Disorientation
The most devastating impact of artificial light occurs when hatchlings emerge from the sand. These tiny creatures, each weighing barely 20 grams, must make a perilous journey from nest to ocean. For millions of years, they have navigated by moving toward the brightest horizon — which, in natural conditions, is always the ocean, reflecting moonlight and starlight.
Artificial lights on or near beaches reverse this cue. Hatchlings crawl away from the ocean toward roads, parking lots, and buildings. This phenomenon, called "disorientation" or "misorientation," leads to:
- Exhaustion and dehydration: Hatchlings expend their limited energy reserves crawling in the wrong direction
- Predation: Disoriented hatchlings are easy prey for crabs, birds, and other predators
- Vehicle strikes: Hatchlings that reach roads are killed by passing vehicles
- Entrapment: Many become trapped in storm drains, behind curbs, or in vegetation
On brightly lit beaches, hatchling mortality from disorientation can exceed 50%.
The Save Darkness Approach
Our Turtle-Safe Coast initiative at Rushikulya takes a community-centered approach:
Lighting Retrofits: We work with coastal communities to replace white lights near nesting beaches with amber-filtered, fully shielded fixtures. Amber light (long wavelength) has minimal impact on turtle behavior compared to white or blue-rich light.
Community Education: We engage fishing communities, resort operators, and local authorities through workshops and demonstrations, explaining the link between their lights and turtle mortality.
Night Patrols: Trained volunteers patrol nesting beaches during peak season to rescue disoriented hatchlings and document the effectiveness of lighting changes.
Scientific Monitoring: We collaborate with marine biologists to measure the impact of our interventions on nesting frequency and hatchling success rates.
What You Can Do
If you live near a coastal area:
- Use amber or red outdoor lights during nesting season (October-March on India's east coast)
- Draw curtains on ocean-facing windows at night
- Avoid using flashlights or phone screens on beaches at night
- Report disoriented hatchlings to local forest department or wildlife rescue
- Support Save Darkness's Turtle-Safe Coast campaign
These ancient mariners have survived asteroid impacts, ice ages, and continental shifts. It would be tragic if they were undone by something as simple — and as fixable — as a poorly placed light.
