Date of Award
Campus Access Dissertation
Doctor of Philosophy (PhD)
Marine Sciences and Technology
American lobster, Homarus americanus, H Milne Edwards 1837, are an ecologically, economically, and culturally valuable marine resource for the coastal communities in the Gulf of Maine (GoM). The American lobster fishery is the most valuable commercial fishery in the United States, supporting thousands of jobs and generating hundreds of millions in annual revenue. The GoM region, meanwhile, is warming three to four times faster than the rest of the world’s oceans while its sea surface is also rapidly acidifying due to anthropogenic climate change. Lobsters are protected from predators, injury, and microbial intrusion by a resilient mineralized, chitin-based exoskeleton, the development of which is controlled by expression of key genes in sync with the molt cycle. Scanning electron microscopy (SEM) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) were used to evaluate the effects of ocean warming (OW) and acidification (OA) on juvenile lobster shell mineralogy and epibiont abundance (chapter 2), and RNAseq and RT-qPCR to examine impacts of these stressors on gene expression (chapter 3).
The combination of OW/OA induced the upregulation of genes pertaining to cuticle development, including genes that regulate calcification inhibition, while the concentration of calcium and magnesium in the shell was found to be significantly lower than in control lobsters. This suggests that shell formation is being affected and mineral formation may be inhibited by the combination of ocean warming and acidification. Genes critical to innate immunity trended toward downregulation under combined OW/OA, while epibiont abundance increased, indicating immune response may be suppressed and a dysbiosis of the epicuticle can occur under these conditions, which may increase the likelihood of disease. The work completed in chapters 2 and 3 was then used in chapter 4 to inform the development of a unique STEM module that was successful in increasing the climate literacy of middle school students by teaching climate change through the lens of a lobster. This dissertation expands our understanding of lobster biomineralization and gene expression under the stress of warming and acidification. The results may help support the continued management of the American lobster fishery in the face of worsening climate change.
San Antonio, Christine Marie, "Examining and Communicating the Effects of Climate Change on Biomineralization, Gene Expression and Epibiont Abundance in Juvenile American Lobster, Homarus Americanus" (2021). Graduate Doctoral Dissertations. 706.