Date of Award

Summer 8-31-2025

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Marine Biology

First Committee Advisor

Kristina Cammen

Second Committee Member

Heather Hamlin

Third Committee Member

Benjamin King

Additional Committee Members

Pauline Kamath

Laura Rickard

Abstract

Following historical exploitation to near extirpation, federal protection over the past several decades has resulted in the recovery of some but not all marine mammal species in the United States. Within this context, my dissertation explores dynamics underlying rebounding pinniped species and declining North Atlantic right whales (NARW; Eubalaena glacialis) in the Northwest Atlantic (NWA) ocean.

Gray (Halichoerus grypus) and harbor (Phoca vitulina) seals in the NWA have both experienced population growth in recent decades but are threatened by cyclical outbreaks of influenza A virus (IAV) and phocine distemper virus (PDV). Although both species are exposed to IAV and PDV, large scale mortality events associated with these pathogens mostly involve harbor seals while gray seals experience limited morbidity and mortality. Chapters 2-5 of my dissertation draw upon methods from molecular ecology, immunology, and toxicology to describe impacts of infectious disease and environmental contaminants on pinnipeds. I used whole blood RNA sequencing to identify molecular mechanisms associated with IAV infection in gray seal pups. I analyzed polychlorinated biphenyl concentrations and their impact on IAV prevalence, gene expression, and cytokine production in gray seal pups. In addition, I identified harbor seal genetic variants that are associated with surviving an outbreak of PDV. These studies have found that gray seals show a marked decrease in gene expression but no change in cytokine concentrations during IAV infections, and that PCBs similarly only impact gray seals at a lower biological level (i.e., gene expression, not cytokines or IAV infection). In harbor seals, genetic variants in the immune system and nervous system may contribute towards disease resistance to PDV. These studies contribute to our understanding of the dynamics underlying the spread of infectious disease in coastal marine ecosystems.

In contrast to pinnipeds, NARW are one of the most endangered large whale species, threatened by entanglements in fishing gear among other stressors. Chapter 6 of my dissertation draws upon social science methods to explore the socio-economic impacts of recent regulations on Mine’s lobster industry. Through a state-issued survey, I found that fishermen exhibit differences in regulatory compliance that varies across fishing operation size, age, and area of fishing (i.e., state vs federal waters). In addition, members of the lobster fleet experience disproportionate impacts, with trends in gear loss related to socio-demographics, geographical location, and fishing operation size. This research highlights the importance of balancing perspectives in marine conservation policy for the goal of achieving success for human, animal, and environmental health.

Overall, my dissertation aims to understand social, ecological, and biological dynamics that underlie the current status of marine mammal populations in the NWA. My research advances scientific knowledge while contributing to effective marine mammal health monitoring and management in the NWA.

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