Date of Award



© 2023 Melissa Butler

Document Type


Degree Name

Master of Science in Marine Sciences


Marine Science

First Advisor

Markus Frederich

Second Advisor

Alicia Williams

Third Advisor

Calvin Vary


Lipids are fundamental components of many biological structures and compositions of these molecular species can alter with diet. Differences in lipid membrane composition can impact the functioning of membranes and proteins subsequently altering the organism’s ability to respond to stressful conditions. American lobsters (Homarus americanus) are an economically important shellfish in New England and are sometimes kept intermittently in lobster impoundments (pounds) for months where they are often fed herring, which differs from the assumed natural diet of wild-caught lobsters. In this study, we compared the lipid composition of lobsters obtained from the wild and pounds that were fed exclusively herring (pound-fed) or mussels (wild-fed) and measured whether this leads to differences in phenotype. The present study investigates the cellular mechanisms involved in the plasticity of thermal thresholds by assessing lipid membrane composition through lipidomic analysis, mitochondrial efficiency using Seahorse XF assays, and gene expression of cellular stress markers with qPCR. Here, thermal tolerance of whole animals is determined to be reflected by measurements of heart rate, ventilation rate, and hemolymph oxygenation to determine the underlying metabolic differences involved in stress response. It was observed that thermal thresholds are not affected by differences in lipid composition, mitochondrial efficiency, and gene expression attributed to diet and origin. These molecular variances did not manifest into differences in thermal tolerance calling for additional research to identify the level of molecular disparities that would result in identifiable differences in thermal tolerance. This research provides methods for mitochondrial efficiency in the American lobster for the first time using an Agilent Seahorse XFe96 Analyzer. Additionally, we identify lipid biomarkers that have the potential for use in medical research. Together, these studies provide the groundwork for further investigation determining stress response in this, and other species, in the face of climate change.


Master's thesis

Available for download on Thursday, August 07, 2025

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