Meeting Abstract

P1.177  Saturday, Jan. 4 15:30  A Comparative Study of Growth Patterns in Juvenile Sea Turtles PATE, J.H.*; SALMON, M.; Florida Atlantic University; Florida Atlantic University jpate10@fau.edu

Loggerhead sea turtles (Caretta caretta) emerge from Florida beaches as hatchlings and return decades later to the same regional beaches to lay their eggs. How they accomplish this feat of migration is unknown. It has been hypothesized that the turtles imprint to the magnetic field at the beach during some portion of their early development and then use this information to return to the same general region as adults. If loggerhead turtles do imprint to the magnetic properties of the beach, then that period of imprinting might occur during embryonic development. Furthermore, we speculated that their might exist a sensitive period during embryonic development during when this process might occur. We experimentally tested for a sensitive period during embryonic development by distorting the magnetic field around clutches during different portions of incubation. We created three experimental groups in which clutches were surrounded by magnets during the beginning, middle or end of incubation. Control nests were either left undisturbed or exposed to non-magnetic aluminum bars; thus, both control groups incubated in the ambient magnetic field. Upon hatching, turtles were tested for their ability to orient while swimming in total darkness, using only magnetic cues. If the experimental turtles demonstrated this ability, then they were considered behaviorally competent and the corresponding time of exposure to a distorted magnetic field during development was not considered a part sensitive period. Turtles in both control groups oriented normally but all three experimental groups failed to show significant orientation. These results suggest that for loggerhead sea turtles, an ability to use a magnetic compass for orientation requires exposure to a natural magnetic field for the entire period of incubation.