In partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Ocean Science & Engineering

In the School of Earth and Atmospheric Sciences

Skylar J. Lama

Will defend her dissertation

UNDERSTANDING THE PHYSICAL ENVIRONMENT OF A FRENCH POLYNESIAN CORAL REEF ECOSYSTEM USING OCEAN MODELING, ACOUSTICS, AND MACHINE LEARNING

April 1st, 2026 at 2 PM

 Ford ES&T, Room 3243 (The Ocean Room)

Zoom Link: https://gatech.zoom.us/j/4690352013

 Thesis Advisors:

Annalisa Bracco, Ph.D.

School of Earth and Atmospheric Science

Georgia Institute of Technology

Karim Sabra, Ph.D.

School of Mechanical Engineering

Georgia Institute of Technology

Committee Members:

Lauren Freeman, Ph.D.

NUWC, Division Newport

Mark Hay, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Lauren Speare, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

ABSTRACT:

Coral reefs are among the most biodiverse and economically valuable marine ecosystems, supporting local communities, fisheries, coastal protection, and tourism. However, these systems are facing accelerated degradation driven by anthropogenic ocean warming, which leads to coral bleaching and inevitably, coral mortality. Understanding the mechanisms that promote reef resilience and recovery is essential for effective restoration and conservation efforts. In the Pacific and Indian Oceans, many reefs have shown relatively quick recovery in coral coverage following intense bleaching. Specifically, French Polynesian reefs have shown remarkable recovery despite multiple bleaching events, compounded with Crown of Thorns Sea-Star outbreaks over the past three decades, making the area a compelling case study. Such repeated recovery suggests the presence of ecological and/or physical processes that enhance resilience. By focusing on interdisciplinary tools, in this thesis I investigate the physical environment in Moorea reefs and uncover mechanisms influencing coral recovery while improving upon monitoring techniques. Each chapter aims to build a stronger understanding of the ways we can study how organisms within a coral reef interact with their fluid environment, either through the overall circulation or the acoustic activity that characterizes the reefs and can be used to interpret reef health. In Chapter 1 I use Lagrangian particle transport modeling to confirm the importance of long-range coral larval connectivity (across 100’s of km) in the Society Archipelago of French Polynesia. In Chapter 2 I use coral reef acoustic recordings collected from fringing reefs in Moorea to reveal frequency and diel patterns on the ecological level (10’s of m) and compare the soundscapes of two nearby reefs with different benthic structures. Lastly, in Chapter 3 I utilize an unsupervised autoencoder along with transfer learning techniques to automate the classification of individual fish calls within the soundscape along with their direction of arrival.

My thesis highlights the importance of interdisciplinary approaches in ocean science, linking physical oceanography with small-scale acoustic ecology to improve upon coral reef monitoring and the development of mitigation strategies.