When you’re a baby sea turtle racing from the nest to the ocean, speed is key. But what happens if lights beaming from condos pull you in the wrong direction?
To find out, scientists at Florida Atlantic University came up with an unusual solution: a tiny turtle treadmill.
To test the energy extended and time spent crawling, lead author Sarah Milton collected 150 loggerhead and green sea turtle hatchlings from nests in Palm Beach County — which were safely released following their workout. Using tiny enclosed treadmills, they simulated lighting typical of an urban coastal beach. They measured the turtles’ oxygen intake and lactate levels to track energy levels, then compared them to disoriented turtles they tested on the beach.
After turtles hatch, they usually make it to the ocean in a mad dash that takes just a few minutes. The scramble, according to researchers, occurs over the first 24 hours as dozens hatch from a single nest. Turtles instinctively head for bright low horizons and away from tall dark silhouettes, which should pull them toward the surf. But city lighting can lead them in the wrong direction, which can lead to more exposed time looking for the surf.
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Typically, about 50 percent in urban settings make it to sea, Milton said.
Researchers expected to find disoriented turtles more exhausted from their crawl and less able to swim. But the treadmill showed turtles are actually good at gauging their own reserves and take frequent rests.
“We were completely surprised by the results of this study,” Milton said in a statement. “They crawl and rest, crawl and rest and that’s why they weren’t too tired to swim.”
While confirming their outsized stamina was a good thing, Milton said coastal lighting still produces a significant risk because it means hatchlings spend more time exposed to predators or other dangers on the beach.
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