Nature Foundation investigates solutions into light pollution affecting sea turtles

Sea turtle hatchlings rely on their instincts to make it to the ocean – but on Sint Maarten and human-inhabited beaches across the world, lately, those instincts are leading them to their deaths.

After breaking free from their eggs, hatchlings look for downward slanting paths, which naturally lead towards the water. More importantly, they seek out the brightest light they can find. Usually, the most prominent source of light is the moon’s reflection on the ocean. Seems like a solid system, right? But problems arise when sea turtles hatch near artificially illuminated areas. The glaring brightness from bars, hotels, and homes trigger their light-seeking instinct, misdirecting them from the water.

Hatchlings becoming disorientated (Photo credit: Cayman Islands Department of Environment)

Sadly, this will often result in a confused hatchling being lost to dehydration, overheating, beached sargassum, or the many predators that find them as an easy meal. During the summer of 2021, over twenty deceased hatchlings were found by Nature Foundation interns on a property built atop a prominent nesting beach. Unfortunately, these confused hatchlings had unintentionally crawled toward the artificial lights and ended up on pavers, gutters, and the pool skimmers. By morning, the heat of the sun and the chlorine in the pool had caused them to perish.

In recent years, the situation on the beaches of St. Maarten has become critical for female nesting turtles, too. During the 2022 nesting season, the Nature Foundation confirmed only six nests, half as many from the twelve nests found in 2021. Female sea turtles will often refuse to lay their eggs on beaches with excessive light, and leave to find a darker and quieter area.

But there’s a surprisingly simple solution to help reduce the negative effects of artificial lighting. Emma Ruijgrok, a Nature Foundation intern from University van Hall Larenstein in the Netherlands studying Wildlife Management, has been researching St. Maarten’s sea turtle nesting activities over the past four months. She spoke to representatives of the environmental department (DoE) at the Government of the Cayman Islands to hear more about their sea turtle friendly lighting policies.

Jerrica Wood, Sustainable Development Officer and Lauren Dombowsky, Senior Environmental Assessment Officer, informed Ruijgrok that the Cayman Islands recently passed a policy in their official environmental guidelines that made sea turtle-friendly lighting on shorelines mandatory. The outcome has been very successful: the DoE has identified an increase in turtle nesting on the beaches of the Cayman Islands over the last five years, and participating properties have been very pleased from an aesthetic perspective. The increase in the success rate of sea turtle hatchlings on the Cayman Islands indicates that St. Maarten needs a change on the nesting beaches as well if we want to recover our declining sea turtle populations. The simplest solution is turtle-friendly lighting.

Nesting hawksbill (Photo credit: Nature Foundation St. Maarten)

“Although complete darkness is best, we can compromise on land by replacing regular bulbs with longer-wavelength red or warm amber ones,” said Ruijgrok. “Sea turtles mainly see blue, yellow and green colors. But they don’t see these warm amber bulbs very well.”

Successfully transitioning beach property owners to sea-turtle friendly lights is in line with St. Maarten’s Nature Conservation Plan for 2021-2025. In the plan, Policy Objective 2 states that by 2022, there should be improved protection and management of sensitive species, as well as an improved understanding of the status of their natural environment.

The Nature Foundation wants to support this policy objective by embarking on a campaign to motivate beach property owners to install sea-turtle friendly lights. Currently, the Nature Foundation is looking into external funding to provide some beachfront properties with this lighting to spread awareness about their importance and encourage their neighbors to make the switch too.

“I am extremely excited to introduce sea turtle-friendly lighting here on the island in order to improve the future of sea turtle nesting populations,” added Ruijgrok.

Making the change

It is important to note that turtles are least attracted to long-wavelength turtle-friendly lighting, but they are not blind to it. If the beach is illuminated, even with turtle-friendly lighting, turtles may still perceive the land as brighter than the ocean and follow this lighting away from the sea. Therefore, all lighting, including turtle-friendly lighting, must comply with the following general principle: “Lighting must not directly, indirectly or cumulatively illuminate the beach.”

The Florida Fish and Wildlife Conservation Commission (FWC) has developed a certification for turtle-friendly lighting fixtures and fittings, as this has been a legal requirement in the United States for more than 20 years. This list features FWC-approved lighting fixtures that have been field-tested and ensure the safety of humans, flora and fauna.

To achieve this, turtle friendly lighting fixtures are typically downward directed and the concept of turtle friendly lighting follows three key principles:

  1. Keep it low – Mount fixtures as low to the ground as possible to reduce light spillage and use the lowest amount of light (lumens) needed for the area.
  2. Keep it long – Use long wavelength light sources (reds, oranges and true ambers) in the appropriate lighting wavelength of 560 nanometers or above.
  3. Keep it shielded – Fully shield the point source of light (i.e. the bulb and/or glowing lens) so that it is not directly visible from the beach.
Poor and good examples of bulb appearances. (Photo credit: Florida Fish and Wildlife Conservation Commission)

If you would like to know more about sea turtle-friendly lighting or are interested in its application on your property, please contact the Nature Foundation by emailing or calling (+1) 721-544-4267.​

The Nature Foundation is a non-profit organization that assists the government of Sint Maarten in all issues related to the natural environment and its conservation. As the scientific and management authority of the Man o War Shoal Marine Park, the Nature Foundation has been active in scientific research, education initiatives, and policy recommendations since 1997.