All ETDs from UAB

Advisory Committee Chair

Thane Wibbels

Advisory Committee Members

Jennifer Layton

Ken Marion

Document Type

Thesis

Date of Award

2022

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

The Kemp’s ridley sea turtle (Lepidochelys kempii) has temperature-dependent sex determination (TSD) where the incubation temperature of the egg determines the sex of the hatchling. This has significant implications for the ecology, evolution, and conservation of this species because it can affect sex ratios. The studies presented in this thesis address hatchling sex ratios produced in Kemp’s ridley conservation programs using both natural as well as manipulated incubation regimes. First, a histology-based study was utilized to investigate sex ratios produced at the Padre Island National Seashore from 2002-2019. The results indicate that a female bias has been produced each year through the Kemp’s Ridley Conservation Program. A female bias could be assisting in the recovery of this species. A second study investigated yearly beach temperatures at Rancho Nuevo, the primary nesting beach for the Kemp’s ridley. This study evaluated beach temperatures from 1998-2021. Our results indicate that early in the nesting season males are more likely to be produced. In the middle of the nesting season, the temperatures have reached pivotal temperature, leading to more female production from late May through July when the majority of nesting occurs. A third study evaluated viii optimal methodology for predicting hatchling sex ratios in the Kemp’s ridley. This study included the development of an Excel model and a comparison of that model to a previously published R package software program. These models utilize beach temperatures and incubation duration to predict hatchling sex ratios. Additionally, the models were used to predict hatchling sex ratios produced during 2020 on the primary nesting beach. Collectively, these studies provide insight on the long-term impact of temperature on hatchling sex ratios of Kemp’s ridley sea turtles. Further, these findings can provide insight on the potential impact of global climate change on hatchling sex ratios in the future.

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