All ETDs from UAB

Advisory Committee Chair

Thane Wibbels

Advisory Committee Members

Dustin Kemp

Ken Marion

David Owens

Ricardo Tapilatu

Document Type

Dissertation

Date of Award

2020

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

The Kemp’s ridley sea turtle (Lepidochelys kempii) has a regionalized distribution, occur-ring in the Gulf of Mexico and along the Atlantic coast of the United States. It is unique among sea turtles in that it nests during the daytime, at a single, primary nesting beach, and utilizes synchronized, mass nesting events (termed arribadas). This arribada behavior has been hypothesized to enhance nest and hatchling survival through predator satiation and predator avoidance. The aims of this dissertation research are to investigate the ecology and dynamics of arribada nesting and early life-history events in the Kemp’s ridley. Significant, non-random, location-specific aggregations of turtles were detected in nearshore waters off the nesting beach, typically 1-6 days prior to an arribada nesting event. Once on the beach, one or more central areas of high-density nesting along with significantly more false crawl behaviors occurring in these areas of high-density nesting, suggest Kemp’s ridleys may be utilizing multiple cues for aggregation and nesting during arribadas. Predators were observed significantly more often during the time period in which nests from an arribada were on the beach, and at almost all hours over a 24-hour period, suggesting in situ nests are under a near-constant threat of depredation throughout incubation. In situ and egg hatchery nests had emergence times that corresponded to the times during which predators were observed significantly less often on the beach, suggesting the ecological dynamics of the single, primary nesting beach may have selected for behaviors to enhance hatchling survival. The majority of egg hatchery nests emerged during the cooling phase of the daily nest temperature cycle, suggesting hatchlings may be utilizing the daily temperature fluctuations within the nest as a cue during emergence. The heart rate of red-eared slider embryos from fluctuating temperature regimes continued to show significant variation when shifted to the constant temperature treatment, indicating the physiology of the embryo is sensing and responding to environmental temperatures. It is plausible that these daily fluctuations in temperature and heart rate could provide cues for entraining circadian rhythms in developing turtles.

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