Researchers use forensic science to track turtles

Isotopes are variants of the same chemical element. Each variant boasts a different number of neutrons in its nucleus. The ratios between different isotopes serve as chemical signatures, some of which are unique to specific environments. In biology, these certain isotope ratios can help scientists identify where a specimen has been and what it's been eating.

Thousands of sea turtles travel to Alagadi, a beach on the north coast of Cyprus, to breed every year. But the turtles come from a variety of foraging grounds, most traveling hundreds of miles.

Scientists have previously used satellite tracking to identify the turtle's most popular feeding grounds. But when researchers at Exeter measured the isotope ratios of breeding turtles in Cyprus, they identified a new signature.

"This meant we knew where many of the turtles went to forage for food, but our preliminary analysis using stable isotope ratios showed a major foraging area had been missed," Brendan Godley, director of Exeter's Center for Ecology and Conservation, said in a news release.

They used satellite trackers to trace the unique ratio to Lake Bardawil, a shallow saline lake on the northern coast of Egypt.

"A large proportion of turtles had isotope ratios that did not correspond to sites previously identified, and we tracked five of them," Godley said. "Five out of five went to Lake Bardawil."

The ratios measured by scientists proved surprisingly consistent, suggesting most turtles continue to return to the same foraging site year after year.

Researchers believe their latest findings -- detailed this week in the journal Marine Ecology Progress Series -- can serve as a model for future studies using stable isotope ratios.

"Using a combination of this analysis and satellite tracking gives us more reliable data, and this can be used to measure the success of future conservation efforts," said Exeter researcher Phil Bradshaw.