Migratory Behavior of Hatchling Sea Turtles: Evidence for Population-Specific Divergence in the Loggerhead (Caretta caretta L.)

• Other Authors: Madrak, Sheila Veronica (author), Salmon, Michael (Thesis advisor), Florida Atlantic University (Degree grantor)
• Format: Thesis
• Language: English
• Published: Florida Atlantic University
• Subjects: Animal migration > Florida; Sea turtles > Migration > Florida; Predation (Biology); Animal orientation > Florida; North Atlantic
• Online Access: http://purl.flvc.org/fau/fd/FA00000792; https://fau.digital.flvc.org/islandora/object/fau%3A34619/datastream/TN/view/Migratory%20Behavior%20of%20Hatchling%20Sea%20Turtles%3A%20Evidence%20for%20Population-Specific%20Divergence%20in%20the%20Loggerhead%20%28Caretta%20caretta%20L.%29.jpg

Migratory bird and insect populations show differences in orientation direction, timing, and distances moved depending upon where they reside in relation to their migratory goals. These differences presumably occur because of selection for behavioral responses that promote the most efficient migratory strategies among members of each population. The purpose of this study was to determine whether migratory behavior in loggerhead hatchlings differs between populations that exit nesting beaches on the East and West coast of Florida. When the turtles emerge from the nests, they initially show a swimming "frenzy" that serves to distance individuals from shallow coastal waters, displacing them toward oceanic currents that are used to transport the turtles to the North Atlantic Gyre. On the East coast of Florida, turtles swim eastward toward the Florida Current (western portion of the Gulf Stream) located relatively close to the shoreline (on average, 2 km offshore at Miami to 33 km offshore at Melbourne Beach). On the West coast of Florida, turtles swim westward toward the Loop Current in the Gulf of Mexico, which is located farther offshore (150 km offshore at St. Petersburg to over 200 km offshore at the Everglades National Park). In a previous study, we demonstrated that for East coast loggerheads, the frenzy consists of continuous swimming for - 24 h, followed over the next 5 days by postfrenzy (diurnal, with little nocturnal) swimming activity. No comparable data exist that characterize the frenzy period of loggerheads from the West coast ofFlorida. We used identical methods to quantify the migratory activity of hatchlings from the West coast of Florida. Hatchlings were captured as they emerged from nests located between Venice and Sarasota, Florida. They were then tethered in water-filled pools under laboratory conditions, where temperature and photoperiod could be controlled to duplicate conditions used when studying the East coast turtles. Activity was continuously recorded over the next six days. The data ...