Where Do Baby Sea Turtles Spend Their “Lost Years”? Scientists Use Satellite Devices To Track Loggerheads
What do baby turtles do once they hatch and head to sea? Biologists, who until now were unsure about what the hatchlings did during their formative years (also called the "lost years") have attempted to answer this question by attaching small satellite-tracking devices to sea turtles that hatch in the coast of Florida and swim offshore.
The "lost years" refers to the time when the baby sea turtles crawl out of their nests and disappear into the sea where they spend several years before reappearing in coastal waters as large juveniles. This time period is referred to as the "lost years", since not much was known about the habitats or diets of the hatchlings once they were out in the sea.
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"What is exciting is that we provide the first look at the early behavior and movements of young sea turtles in the wild," said University of Central Florida (UCF) biologist Kate Mansfield, the main researcher in this study, according to a press release Tuesday. "Before this study, most of the scientific information about the early life history of sea turtles was inferred through genetics studies, opportunistic sightings offshore, or laboratory-based studies. With real observations of turtles in their natural environment, we are able to examine and reevaluate existing hypotheses about the turtles' early life history. This knowledge may help managers provide better protection for these threatened and endangered species."
The study was conducted by scientists from UCF, Florida Atlantic University, University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, and University of Wisconsin.The scientists attached small solar-powered satellite tags to 17 loggerhead turtles and tracked their movements for 27 to 220 days in the open ocean. The data collected from these devices gave them a better understanding of the turtles' movements, habitat preferences, and the importance of temperature in their early years.
The inferences of the study were as follows:
It was earlier thought that loggerhead turtles hatching from Florida's east coast remained in the currents associated with the North Atlantic subtropical gyre and travelled all the way round the Atlantic while they matured. But new data reveals that the turtles may leave these currents and move into the Sargasso Sea in the middle of the Atlantic. The turtles remain in oceanic waters (traveling between 124 miles to 2,672 miles) off the continental shelf and the loggerhead turtles come the surface of the water.
The team also analyzed the thermal sensors in the satellite tags and found that the turtles' shells showed more heat than anticipated. The young turtles capture this heat by staying in the sea surface where they can absorb the sun's rays. The ocean surface is also covered with a type of sea-weed called Sargassum, which provides food and a natural cover against predators for the hatchlings.
"We propose that young turtles remain at the sea surface to gain a thermal benefit. This makes sense because the turtles are cold blooded animals. By remaining at the sea surface, and by associating with Sargassum habitat, turtles gain a thermal refuge of sorts that may help enhance growth and feeding rates, among other physiological benefits," said Mansfield.
The scientists are still at the nascent stage of understanding the "lost years" of a sea turtle's life, but their efforts will give a much needed boost to conservation efforts of loggerheads and other sea turtles, 80 percent of which use the Florida coast for nesting. Virginia, South America, and the Caribbean are also important nesting grounds for turtles.
"From the time they leave our shores, we don't hear anything about them until they surface near the Canary Islands, which is like their primary school years," said Florida Atlantic University professor Jeannette Wyneken, the study's co- PI and author. "There's a whole lot that happens during the Atlantic crossing that we knew nothing about. Our work helps to redefine Atlantic loggerhead nursery grounds and early loggerhead habitat use."
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