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Effects of in Situ Incubation Temperatures on Hatchling Loggerhead Sea Turtle (Caretta

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Effects of in Situ Incubation Temperatures on Hatchling Loggerhead Sea Turtle (Caretta Effects of In Situ Incubation Temperatures on Hatchling Loggerhead Sea Turtle (Caretta caretta) Morphology, Health Indices, and Locomotor Performance by Kelsey Alexandra Fleming A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Biological Sciences College of Arts and Sciences University of South Florida St. Petersburg Major Professor: Alison Gainsbury, Ph.D. Justin Perrault, Ph.D. Deby Cassill, Ph.D. Jeanette Wyneken, Ph.D. Date of Approval: April 10, 2019 Keywords: scutes, umbilical scar, heart rate, blood, righting, climate change Copyright © 2019, Kelsey Alexandra Fleming ACKNOWLEDGEMENTS First and foremost, I would like to thank my co-advisors, Dr. Alison Gainsbury and Dr. Justin Perrault, for all their support and guidance. The door to Dr. Gainsbury’s office was always open whenever I had questions about my research. Dr. Perrault introduced me to my first sea turtle hatchling and provided invaluable experience working with sea turtles, which I’ll never forget. I would also like to thank my thesis committee members, Dr. Deby Cassill and Dr. Jeanette Wyneken, for their support and comments. Dr. Nicole Stacy analyzed the blood smears for this project, and for that I’m extremely grateful. Additionally, this project would not have been possible without Christina Coppenrath and the numerous staff and volunteers at Loggerhead Marinelife Center that helped with data collection. Lastly, I must express my deep appreciation to Aaron and my family for their continuous support and reassurance throughout my graduate career. I could not have done it without you. TABLE OF CONTENTS LIST OF TABLES ............................................................................................................. iii LIST OF FIGURES ........................................................................................................... iv ABSTRACT .........................................................................................................................v CHAPTER 1: INTRODUCTION ........................................................................................1 Temperature effects on morphology: hatchling size ................................................2 Temperature effects on morphology: abnormal scutes ............................................3 Temperature effects on morphology: umbilical scar as a proxy for yolk mass .......4 Temperature effects on health indices .....................................................................5 Temperature effects on locomotor performance ......................................................6 Temperature effects on stage of development ..........................................................7 Loggerhead sea turtles .............................................................................................9 Objectives and hypotheses .....................................................................................10 CHAPTER 2: MATERIALS AND METHODS ...............................................................11 Study site ................................................................................................................11 Data loggers...........................................................................................................12 Nest selection/monitoring and hatchling collection ..............................................12 Morphological measurements ................................................................................13 Health indices ........................................................................................................14 Locomotor performance.........................................................................................16 Hatching success and stage of development ..........................................................16 Statistical analyses .................................................................................................17 CHAPTER 3: RESULTS ...................................................................................................19 Incubation temperature ..........................................................................................19 Hatching success ....................................................................................................21 Temperature effects on morphology: hatchling size ..............................................22 Temperature effects on morphology: abnormal scutes ..........................................23 Temperature effects on morphology: umbilical scar length and width .................25 Temperature effects on health indices ...................................................................26 Temperature effects on locomotor performance ....................................................32 Temperature effects on stage of development ........................................................33 CHAPTER 4: DISCUSSION .............................................................................................35 Incubation temperatures ........................................................................................36 Temperature effects on morphology: hatchling size ..............................................37 Temperature effects on morphology: abnormal scutes ..........................................39 Temperature effects on morphology: umbilical scar length and width .................40 i Temperature effects on health: heart rate .............................................................41 Temperature effects on health: baseline indices ....................................................42 Temperature effects on health: WBC counts .........................................................45 Temperature effects on locomotor performance ....................................................46 Temperature effects on stage of development ........................................................49 Conclusions ...........................................................................................................50 LITERATURE CITED ......................................................................................................53 ii LIST OF TABLES Table 1: Summary of in situ incubation temperatures for loggerhead sea turtle nests in May, June, and July 2018 (N=5 for each month) .....................................20 Table 2: The effects of incubation temperature on loggerhead (Caretta caretta) hatchling morphology ............................................................................................23 Table 3: Anatomical location, number, and percentage of abnormal scutes by month. ....................................................................................................................24 Table 4: Measures of central tendency and reference intervals for packed cell volume, total solids, glucose, hemoglobin, heart rate, and white blood cell counts with differentials for hatchling loggerhead (Caretta caretta) sea turtles from Florida. ...............................................................................................28 Table 5: Stage of development at death percentages by month for loggerhead (Caretta caretta) embryos ................................................................................34 iii LIST OF FIGURES Figure 1: Location of study site .............................................................................12 Figure 2: In situ incubation temperature profiles for all 15 loggerhead nests obtained from the data loggers. ...............................................................20 Figure 3: Transposed incubation temperatures for all nests to demonstrate differences between month ....................................................................21 Figure 4: Percentage of hatchlings with at least one abnormal scute ....................24 Figure 5: Effects of incubation temperature on umbilical scar width ....................26 Figure 6: Effects of incubation temperature on packed cell volume .....................30 Figure 7: Effects of incubation temperature on hemoglobin .................................31 Figure 8: Effects of incubation temperature on total solids ..................................32 Figure 9. Differences in self-righting response time by month .............................33 iv ABSTRACT Incubation temperatures, in addition to an embryo’s genetic makeup, play crucial roles in development and alter a variety of characteristics in sea turtle embryos. Atmospheric temperatures are currently predicted to rise at least 1.5°C above pre- industrial levels by 2052, potentially impacting embryonic development. Most sea turtle temperature studies document the effects of “high” and “low” incubation temperatures in laboratory-reared nests. This study’s objective was to examine impacts of varying in situ incubation temperatures on loggerhead sea turtle (Caretta caretta) hatchling morphology, health, and locomotor performance. Temperature data loggers were deployed in 15 individual loggerhead nests on Juno Beach, Florida between June and August 2018. In total, 144 hatchlings were measured and sampled. Carapacial scute abnormalities, mass, and morphological measurements (straight carapace length (SCL), straight carapace width (SCW), body depth (BD), front flipper length (FFL), umbilical scar length, and umbilical scar width) were taken. Heart rate was measured using a portable ultrasound and blood was collected to analyze for glucose, packed cell volume, hemoglobin, total solids, and
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