Advisory Committee Chair
Thane Wibbels
Advisory Committee Members
Ken Marion
David W M Owens
Document Type
Thesis
Date of Award
2023
Degree Name by School
Master of Science (MS) College of Arts and Sciences
Abstract
The studies conducted within this thesis used physiological-based methodologies to assess the reproductive and developmental biology of two threatened turtle species. Chapter one investigates the decreased clutch frequency hypothesis as a potential cause for the recent loss in the 19% annual recovery rate in the Kemp’s ridley, Lepidochelys kempii. This study combined ultrasonography, testosterone analysis, and PIT tag assessment methods to re-evaluate the clutch frequency of Kemp’s ridleys nesting at the primary nesting beach of Rancho Nuevo. Results estimated a clutch frequency of 2.6 nests per female per season, suggesting that decreases in clutch frequency are not a potential factor limiting the recovery of this critically endangered species. Chapter two assessed the developmental chronology of secondary sexual characteristics and steroid hormones in the diamondback terrapin, Malachlemys terrapin. Body morphometrics, such as tail length, head size, shell characteristics, and blood levels of steroid hormones testosterone, estradiol, and progesterone were evaluated in three different age classes of terrapins corresponding to the first three years of life. The results indicated that body morphometrics showed significant differences by age two but had considerable overlap between males and females. Females had larger body and head sizes by age two, while males had longer tails and increased levels of testosterone. Estradiol and Progesterone were non-detectable in all age classes. Testosterone may serve as a useful indicator of sex in juvenile terrapins, as there was no overlap in values between males and females in age two.
Recommended Citation
Brannum, Robby Joseph, "Investigating the Reproductive Biology of the Kemp's Ridley Sea Turtle and the Diamondback Terrapin: Implications for Conservation" (2023). All ETDs from UAB. 90.
https://digitalcommons.library.uab.edu/etd-collection/90