Biology ETDs

Publication Date

Spring 4-13-2018

Abstract

Many green sea turtle populations are slowly recuperating from a recent severe decline due to anthropogenic factors including human consumption and mortality related to the fishing industry. Despite being charismatic animals that have been extensively studied, there is still a limited understanding of their feeding strategies and diet plasticity. This research explores the use of hydrogen isotopes in marine ecosystems to better understand green sea turtle ecology. This study is presented in two chapters: I first examined the trophic discrimination factor (D2HNET) for hydrogen isotope (d2H) as a tool to correct hydrogen isotope data for wild populations, and next explored the use of hydrogen isotopes in conjunction with nitrogen and carbon isotopes to study green sea turtle diet and habitat use in Baja California Sur. Together, this research was used to (a) differentiate feeding strategies and habitat use for wild green sea turtles living in different habitats (open ocean versus lagoon) along the Pacific coast of Baja California Sur and (b) determine the utility of hydrogen isotopes to trace regional migration and trophic level patterns in wild sea turtle populations. Results from these studies provide additional evidence of wide feeding plasticity in green sea turtles as has been reported in previous studies. Additionally, this work provides insights regarding inter-individual diet variation within lagoon habitats (specialists vs generalists) in comparison to open ocean habitats where individuals show a small dietary niche breath and feed on prey items at a higher trophic level. This work also supports the use of hydrogen isotopes as a new tool to distinguish between prey items, elucidate local migration patterns, and determine trophic level status within consumers in marine ecosystems.

Language

English

Keywords

stable isotopes, Chelonia mydas, hydrogen isotope, hydrogen trophic discrimination factor

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Seth D. Newsome

Second Committee Member

Jeffrey A. Seminoff

Third Committee Member

Howard L. Snell

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