Abstract

Marine turtles are distributed in temperate, sub-tropical and tropical waters and beaches worldwide, often in areas heavily impacted by humans. Although there are many threats to marine turtle populations, the growing threats of nutrient pollution and harmful algal blooms are relatively understudied despite their widespread impacts on coastal marine ecosystems that marine turtles depend on. By studying juvenile green turtles (Chelonia mydas) in the Indian River Lagoon, Florida, where nutrient pollution and HABs are a widespread and longstanding issue, I aimed to conduct a case study of how these threats may affect this federally Threatened species. In Chapter 2, I used four concurrent, 18-year data sets to characterize and assess the interrelatedness of long-term trends in seagrass cover, macroalgae occurrence, juvenile green turtle abundance, and juvenile green turtle growth rates. From 2000 to 2018, IRL seagrass cover declined precipitously, macroalgae rose slowly through 2011 then declined during two severe HABs, juvenile green turtle abundance declined slowly, and growth rates declined through 2011 then rose through 2018. In Chapter 3, I conducted a 9-year study of juvenile green turtle foraging ecology using a comparative stable isotope approach. I found that carbon and nitrogen stable isotopic variance declined during and after two severe HABs in the IRL. In Chapter 4, I used two complementary methods to assess the diet of juvenile green turtles after two severe algal blooms in order to assess changes compared to previous diet studies. Visual identification of forage items showed that juvenile green turtle diet remained dominated by nutrient-tolerant red macroalgae with smaller components of seagrass and green algae; metabarcoding techniques largely failed to resolve their diet. My results highlight the web of complex effects and responses that factor in to determining the effects of nutrient pollution and HABs on juvenile green turtles. Future studies of habitat selection, foraging ecology, and the effects of these on juvenile green turtle growth and survival are needed to fully assess the threat of nutrient pollution.

Notes

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Graduation Date

2021

Semester

Summer

Advisor

Mansfield, Kate

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Biology

Degree Program

Conservation Biology; Integrative Biology

Format

application/pdf

Identifier

CFE0009117; DP0026450

URL

https://purls.library.ucf.edu/go/DP0026450

Language

English

Release Date

February 2022

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

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