Meeting Abstract

3.2  Jan. 4  THE MAGNETIC MAP OF SEA TURTLES: EVIDENCE FOR MULTIPLE MAGNETIC ELEMENTS WANG, JH*; LOHMANN, CMF; LOHMANN, KJ; University of Hawaii, Manoa; University of North Carolina, Chapel Hill; University of North Carolina, Chapel Hill john.wang@noaa.gov

Juvenile sea turtles take up residence in specific coastal feeding sites and return to these sites after displacement. Previous work has established that such turtles use magnetic map information when navigating to specific destinations. Because newly hatched turtles can detect the intensity and the inclination angle of the field, the magnetic map used by the juvenile turtles might be based on one or both of these parameters. To investigate the organization of their magnetic map system, juvenile green turtles were captured and tethered inside a large magnetic coil system used to reproduce the magnetic field of specific geographic locations. One group was exposed to a field that exists approximately 325 km north of the test site. The second group was exposed to an experimental field; this field paired the intensity of the northern site with an inclination angle 325 km to the south. Turtles exposed to the first field oriented southward as if navigating to their feeding site, whereas turtles exposed to the second field oriented randomly. These results imply that turtles do not rely exclusively on magnetic field intensity; if they did, then turtles tested in the second field should have oriented south. Similarly, turtles do not rely on inclination alone; if they did, then the second field should have elicited northward orientation. The results are consistent with the hypothesis that turtles detect both field parameters and are unable to navigate under unnatural conditions in which the two provide conflicting positional information. Thus, both inclination and intensity appear to play important roles in the ability of turtles to determine geographic position.