Saving the Turtles: How Hatchlings Can Successfully Journey from Nest to Ocean
By Katie Warren
Original article:
Shigetomo Hirama, Blair Witherington, Kristen Kneifl, Andrea Sylvia, Morgan Wideroff, Raymond Carthy
Thousands of sea turtle hatchlings die annually in Florida from the presence of artificial light at night that prevents them from finding their way to the ocean safely and successfully.[1] Artificial lighting on and around beaches disorient the baby turtles, disrupting their sleeping and eating behaviors, migratory patterns, and ability to mate and communicate. Shigetomo Hirama, a researcher at the Fish and Wildlife Institute at the Florida Fish and Wildlife Conservation, working in the Department of Wildlife Ecology and Conservation at the University of Florida, is investigating this consequential impact of light on turtle hatchlings by doing something that has never been done before.
Hirama is studying one of Florida’s most primitive and natural beaches, the Playalinda in Brevard County, to collect data that will be used as a model for implementing turtle-friendly beach lighting and inform other beaches around the state. The Playalinda is the best protected beach from light pollution in Florida because of its high vegetation to block out light and hasn’t been touched by humans for beach erosion or cleaning. It’s as “au naturale” as you can get for a state that has so many heavily populated shorelines and beachfront cities and towns. The research being conducted here is meant to do two things: define a baseline understanding of how turtle hatchings go without the interference of artificial light, and determine what environmental factors affect the hatchings the most. No other studies have explored turtle hatchling patterns in a naturally-lighted setting, which makes this research super interesting and important.
Hirama’s research team would go out to Playalinda after sunrise to collect information about how the baby turtles made their journey to the ocean by looking at the footprints leaving 87 different nests. They measured the accuracy, precision, and direction of these tiny footprints to help get an idea of where the turtles were heading by finding the average direction and determining how far off it was from the direction of the ocean. They also recorded seven different environmental factors: beach slope, distance between nests and the beach dunes, dune height, moon brightness, vertical distance from the nest and tops of the surrounding plants, cloud cover, and humidity. It was found that nest-to-dune distance, cloud cover, and nest-to-vegetation-tops had the strongest influence on hatchling success.
According to Hirama et al., “The results of the present study showed high accuracy and precision of hatchling orientation toward the sea, as we predicted for a naturally lighted beach”.[2] This means that the baby turtles at Playalinda did not get disoriented; their paths were relatively straight, and all followed a correlated direction that led them successfully to the ocean. This finding is actually a pretty rare phenomenon on Florida beaches since turtle hatchling disorientation is so common. Baby turtles rely on their instinct to travel in the direction of the brightest object they see, which ideally should be the moonlight bouncing off the ocean. However, with the presence of bright lights on the beach from surrounding buildings and streets, turtles get confused and are lured away from the safety of the water. This is deadly for these baby turtles, because they are more vulnerable to predators and motorists, and could even drown in swimming pools.[3]
The findings in Hirama’s study are vital in protecting our vulnerable wildlife and increasing turtle hatchling survival rates because they will inform beaches of the changes they need to make to better manage their artificial light. Turtles in naturally-lighted habitats perform better and get less confused because of the absence of lights from surrounding civilization. When hatchlings are less disoriented, they are more likely to safely travel from their nests to the ocean and have higher survival rates.
This study also acts as a baseline for future research on beaches that have different environmental qualities and landscapes, such as different beach slopes or dune features. Additionally, it could also shed light on (pun intended) beaches that are thought to be minimally affected by light pollution, like wildlife preserves that are close to populated areas. “Results of hatching orientation that significantly differ from representative baselines may indicate the need to restore the beach environments, and especially, to reduce visible artificial lighting,” wrote Hirama et al.[4] With this new ability to compare turtle hatchling success to an ideal situation, beaches can now model their lighting design in a turtle-friendly way to help them stay safe during their journey from the nest and onward.
[1] “Artificial Lighting and Sea Turtle Hatchling Behavior.”
[2] “Environmental Factors Predicting the Orientation of Sea Turtle Hatchlings on a Naturally Lighted Beach” 5.
[3] “Information About Sea Turtles: Threats from Artificial Lighting”.
[4] “Environmental Factors Predicting the Orientation of Sea Turtle Hatchlings on a Naturally Lighted Beach” 6.
References
Florida Fish and Wildlife Conservation Commission. c1999-2021. Artificial
Lighting and Sea Turtle Hatchling Behavior. State of Florida: Tallahassee
(FL); [accessed 2021 July 22].
https://myfwc.com/research/wildlife/seaturtles/threats/artificial-lighting/
Hirama S, Witherington B, Kneifl K, Sylvia A, Wideroff M, Carthy R. 2021.
Environmental Factors Predicting the Orientation of Sea Turtle Hatchlings on a Naturally Lighted Beach: A Baseline for Light Management Goals. Journal of Experimental Marine Biology and Ecology. 541. https://doi.org/10.1016/j.jembe.2021.151568.
Sea Turtle Conservancy. c1996-2021. Information About Sea Turtles: Threats from Artificial Lighting. Gainesville (FL); [accessed 2021 July 22].
https://www.conserveturtles.org/information-sea-turtles-threatsartificial-lighting/