Costa Rica’s Leatherback Sea Turtles May Spend “Lost Years” on Hatchling Highways
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Costa Rica’s Leatherback Sea Turtles may spend “lost years” on hatchling highways: lessons from Playa Grande
Scientists know so little about the early life history of the critically endangered leatherback turtle, from hatching to adulthood, that they call this period the “lost years.” But a team researching the nesting site of Playa Grande, the location of the Earthwatch project Costa Rican Sea Turtles, has just helped to fill in some of the gaps—which is great news for this critically endangered species.
The beach is exposed to ocean currents that improve the hatchlings’ chances of survival, according to the team of researchers, who include Earthwatch scientist Dr. James Spotila. Their findings were published recently in Proceedings of the Royal Society B: Biological Sciences.
More specifically, Playa Grande’s large-scale eddies - circular currents that move in a different direction from the main current - along with other currents, carry the turtles safely offshore during the nesting period, serving as “hatchling highways” to the sea. The currents carry the turtles away from the grips of coastal-dwelling predators and into the relative safety of the sea, where they can do things like munch on jellyfish and grow up. More than 10 years later, when they have reached maturity, the females return to the shore to nest.
During the January to April nesting season from 2000 to 2008, the scientists studied the movement of currents at four nesting beaches, including Playa Grande, by means of fluids used to track water flow known as passive tracers. These tracers reveal how the young turtles are carried by currents, as hatchlings don’t develop full swimming abilities until after the first six months of their lives. The eddies and coastal currents likely play a critical role in getting the hatchlings safely to sea. This information is crucial for understanding the turtles’ ecology and informing conservation strategies.
Dr. Spotila adds, “The leatherbacks are holding on with their flipper tips. We need to get fishing under control real soon or the turtles will be gone."
The full paper can be found at rspb.royalsocietypublishing.org.