Graduation Year
2025
Document Type
Thesis
Degree
M.S.
Degree Name
Master of Science (M.S.)
Degree Granting Department
Biology (Integrative Biology)
Major Professor
Deby L. Cassill, Ph.D.
Committee Member
Justin R. Perrault, Ph.D.
Committee Member
J. Sean Doody, Ph.D.
Committee Member
Brian Maitner, Ph.D.
Keywords
Adaptive management, Environmental predictors, Long-term monitoring, Phenological modeling, Reproductive timing, Sea turtles
Abstract
Climate change is altering environmental conditions worldwide, affecting the timing and success of critical life-history events in many species. The timing of leatherback sea turtle (Dermochelys coriacea) nesting behavior is closely linked to seasonal and local environmental conditions, yet multi-decadal shifts in nesting phenology associated with climate change remain poorly understood. Using long-term leatherback nesting and saturation tagging data (2000––2025), I first examined patterns in emergence dates, emergence times per night, and the number of nesting leatherbacks per night over this 26-year period. Moreover, I examined the impact of environmental covariates including day length, water temperature, precipitation, wind speed, barometric pressure, tide height, moon phase, and El Niño Southern Oscillation (ENSO) state on date of emergence, time of emergence, and number of leatherback sea turtles emerging per night. I show that first and median emergence dates of leatherbacks nesting in central and eastern Florida have advanced significantly over 26 years by -1.13 and -0.46 days per year respectively, while last emergence dates have remained stable. Predictors of date of first nest included day length, water temperature, precipitation, wind speed, and barometric pressure. Time of emergence per night was influenced by warmer waters and higher predicted tides, which were associated with later emergence. By revealing how environmental factors shape leatherback nesting behavior, these results allow for better prediction of nest timing, incubation temperatures, and future phenological shifts. Understanding these patterns is essential for assessing the potential impacts of climate change on leatherback populations and guiding adaptive management and conservation efforts.
Scholar Commons Citation
Dejohn, Frank Jesse, "Phenological shifts in nesting behavior of leatherback sea turtles, Dermochelys coriacea, along Central and Southeastern Florida beaches" (2025). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/11265
