Green sea turtles enter the open ocean as soon as they hatch off the coast of Florida and then seem to disappear for a spell – now new tracking data shows that after surfing in the Gulf Stream north, many turtles fall out of the current to enter the Sargasso Sea. , an oasis of cozy algae and plenty of food.
In a new study published Tuesday (May 4th) in the journal Notices of the Royal Society B, scientists attached solar-labeled satellite labels to 21 green sea turtles (Chelonia mydas) of “young child” age, which means about 3 to 9 months. The young turtles weighed just over 10.5 ounces (300 grams) and their shells were about 5 to 7 inches long (1
Despite the obstacles, for better protection of the sea turtle populations, “we really need to get labels for some of these little boys,” said first author Kate Mansfield, director of the Sea Turtle Research Group and an associate professor in the Department of Biology at the University of Central Florida. The migration of young turtles into the open ocean is often called the “lost years” because scientists know so little about what the animals are about before returning to shore as “teenagers.”
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“Sea turtles generally don’t reach maturity for at least a few decades. And the years they grow up, we don’t know much about them,” Mansfield said. Now, thanks to tracking data, “the Sargasso Sea is emerging as an important habitat for sea turtles in their early stages of life,” marking the region as critical to species conservation, she said.
The adventures of young children turtles
The Sargasso Sea, named after a free-floating brown genus seaweed Called Sargasum, is the only sea whose edge is determined by ocean currents and not by land, according to the National Oceanic and Atmospheric Administration (NOAA). The sea is located in the so-called North Atlantic subtropical plain, a large circle composed of four main ocean currents: the Gulf Stream to the west, the North Atlantic to the north, the Canary Stream to the east and the North Atlantic equatorial Current to the south.
In past studies, researchers have noticed young green sea turtles, as well as quarrels (Carriage carriage), passively floating in these currents, often on a mat from Sargasum, Mansfield said. These observations, as well as the observations of Florida-born turtles in the eastern Atlantic, suggested that the turtles could simply make a large circle around the wire before heading back to the United States as young.
But Mansfield and her colleagues wanted solid evidence of this migration, while pointing out how long turtles usually stay at sea. Are they absent for a year, “or are they out for a decade? These are pretty basic questions,” said study author Janet Wyken, a professor of biological sciences at the Florida Atlantic University.
Satellite markers designed for adult turtles “looked like bricks” the size of a cell phone, Mansfield said; but with the advent of small markers about the length of the finger segment, the team could begin tracking young turtles, she said. They started arguing and tagged 17 turtles in a 2014 study; they found that instead of passing passively, the disputants often went out of the currents to swim in warm, nutrient-rich waters, including those in the Sargasso Sea, the magazine reported. Notices of the Royal Society B.
Green sea turtles may be such active swimmers once they reach the high seas, the team thought, so they set about repeating the study with C. mydas hatched.
The team collected the hatchlings from Boca Raton, located on the southeast coast of Florida, and then returned them to the lab to grow for several months. Although the teams’ satellite tags are small, they are still too large for freshly hatched turtles, Mansfield said. The team initially tried to attach the labels using the same glue they used for the spores, a type of manicure acrylic that eventually peeled off as the animals grew.
“But that didn’t happen with the green turtles,” Mansfield said. The structure of a young green turtle’s shell feels “waxy”, somewhat like a human claw soaked in cuticle oil, while the carved shells are not as smooth, Wyken said. The team is testing many adhesives – those used to cement fillings in teeth, those that are used to attach theatrical dentures to the skin, you say – before finding one that sticks to slippery turtles.
This eventually became marine urethane adhesives commonly used to seal boats; the glue is flexible enough to stretch as the turtles grow, but once the turtles reach a certain size, it pops up immediately.
After making sure the glue was safe and sticky enough, the team released their turtles into the western Atlantic and tracked them for an average of 66 days; they were able to follow several turtles for more than 100 days and one for 152 days. They found that their turtles mostly swam near the surface of the ocean, similar to collisions, and also on the shores of the Gulf Stream. In general, however, the turtles dropped out of the Gulf Stream and the neighboring North Atlantic Stream earlier than the Swaris.
About two-thirds of these green sea turtles then placed it high in the Sargasso Sea, where they remained until their labels ceased to be transmitted; this hinted that Sargasso served as an attractive nursery for turtles.
“This habitat makes sense,” Mansfield said. Algae provide camouflage for small turtles, while slowing the flow of water and thus allowing the sun to heat its surface. As cold-blooded, sea turtles need warm water to survive, and their growth slows significantly when they become too cold. Other young marine animals, such as shrimp, crabs and fish, also grow in Sargasum and provide food for growing turtles.
But while some of the young sea turtles flock to Sargasso, there is still the question of why some swim to the sea while others stay afloat, Mansfield said. It may be related to the fact that the amount of Sargasum and its prevalence in the eastern United States varies by season, according to a 2011 study International Journal of Remote Monitoring.
So while some turtles encounter Sargasum in the Gulf Stream and follow it to the Sargasso Sea, “there may be some who miss this Sargasum boat and to hang in the currents, “Mansfield said.
And when the turtles reach the Sargasso Sea, another question arises: How long do they stay?
“I guess these animals will be there for about two to three years,” Wyken said, “but that’s a ‘pure guess,'” she added. “If you’re safe, why leave it?” Mansfield said, echoing Wyken’s mood. Green sea turtles usually return to Florida as minors and remain in coastal habitats until adulthood, feasting on algae, seagrass and jellyfish. Until they reach the critical transition point, the Sargasso Sea probably meets many of the turtles’ needs.
But to know exactly how long they stay in the algae-laden habitat, scientists will need more tracking data, Mansfield said. Now that they have tracked turtles on their way to Sargasso, the team could potentially search for turtles that already live there and attach labels to them on the spot, she said. No matter how long the turtles stay, Sargasso seems to be an important habitat for young animals. To ensure that turtles will grow to lay their own eggs in the future, the sea must be preserved, she said.
“The Sargasso Sea cannot be turned into another landfill. It must be recognized as a habitat that is important for endangered species,” Weineken said. “This is probably not just a story about green turtles,” given that other juvenile marine animals also grow among algae, she added.
Originally published in Live Science.