In partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Ocean Science & Engineering

In the

School of Biological Sciences

Cameron Perry

Will defend his dissertation

From microbes to whale sharks: how studying some of the smallest and largest organisms can inform elasmobranch biology and ecology

Friday, July 19th, 2024, 1:00 PM

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

https://gatech.zoom.us/j/3735370829?omn=95432173787

 Thesis Advisor:

Frank Stewart, Ph.D.

Department of Microbiology & Cell Biology 

Montana State University 

Committee Members:

Mark Hay, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Konstantinos (Kostas) Konstantinidis, Ph.D.

Civil and Environmental Engineering

Georgia Institute of Technology

Emanuele Di Lorenzo, Ph.D.

Department of Earth, Environmental, and Planetary Sciences

Brown University

& School of Earth and Atmospheric Sciences

Georgia Institute of Technology

Alistair Dove, Ph.D.

Museum of Science and History

ABSTRACT: Ecological processes act across a variety of spatial and temporal scales and in order to understand a system or organism it is vital to explore different scales and develop connections between them. For threatened species, such as elasmobranchs, management plans should consider scale to bolster conservation efforts and protection. For some of these species we lack basic information on life history, physiology, and health, highlighting the importance of studying elasmobranchs across a range of scales to holistically understand their biology, ecology, and aid in conservation planning. Whale sharks (Rhincodon typus) are the largest extant fish in the sea; however, there are still large knowledge gaps in their biology and ecology. Information about whale shark reproduction and mating has proven difficult due to logistical constraints of studying a large highly migratory pelagic species. Two reports of whale shark mating, the only two of its kind, were reported in waters surrounding the remote South Atlantic Island of St. Helena. Dedicated research expeditions were conducted to St, Helena to understand more about whale sharks within these waters. Population demographics were analyzed via photographic identification and a variety of satellite and acoustic tags were used to explore both large scale and fine scale movements of whale sharks within St. Helena waters. Deployment of CATS camera tags and MiniPAT tags allowed for exploration of the subsurface/diving behaviors and conspecific interactions of whale sharks in St. Helena. Due to its likely role in the reproductive ecology of the whale shark, St. Helena represents a critical habitat for this endangered species.
            While large scale macroecological questions are necessary for understanding the fitness, health, and interactions of elasmobranchs with other animals and their environment, factors affecting elasmobranchs also occur at the scale of animal-microbe interactions. Understanding elasmobranch–microbiome interactions are critical for predicting how sharks and rays respond to a changing ocean and for managing healthy populations in managed care. Research to understand elasmobranch ecology and conservation has begun to explore the role of body-associated microbiomes in shaping elasmobranch health. There have been burgeoning efforts to understand elasmobranch microbiomes, exploring microbiome variation among gastrointestinal, oral, skin, and blood-associated niches. I reviewed these efforts and identified major bacterial lineages in the microbiome, challenges to the field, key unanswered questions, and avenues for future work. Furthermore, water can act as source of beneficial microbes, which many organisms can recruit and utilize for host health; however, it can also allow individuals to interact with harmful microbes that may cause disease or harm. Therefore, understanding of environmental microbiomes is important for complete understanding of host-associated microbiomes in both natural and artificial settings. I sampled the water column microbiome of Georgia Aquarium’s dedicated elasmobranch exhibit to better understand how microbiomes are created and maintained. This provided insight into the successional trajectories and influence of elasmobranchs on environmental microbiomes yielding valuable information about exhibit design and maintenance.