Dissertation Defense - David Armstrong

SUBJECT: THE MECHANISMS OF CORAL CALCIFICATION UNDER OCEAN ACIDIFICATION.

SPEAKER: David A. Armstrong

MAJOR ADVISOR: Dr. Keisha Bahr

COMMITTEE MEMBERS:   Dr. Conall McNicholl, Dr. Christopher Hollenbeck, Dr. Xinping Hu, and Dr. Mikaela Boham

DATE: Friday, March 27, 2026 

TIME: 1 P.M. CDT

MEETING ID: 985 7948 6912

PASSCODE: 346481

ABSTRACT

Coral reefs support global biodiversity at a magnitude far greater than the species that constitute the reef environment alone. The construction of three-dimensional reef structure is largely carried out by corals through a process known as calcification, which is fundamental to providing habitat for dependent marine species. Calcification in corals is a complex biogenic process maintained by intricate internal and external environmental interactions. However, global oceanic conditions are changing at an unprecedented rate due to the rise of anthropogenic CO₂, which is acidifying the marine environment. Ocean acidification (OA) remains the greatest chemical threat to coral calcification. Therefore, this dissertation addresses, foremost, the physical environment through interactions between coral material flux within the quiescent concentration boundary layer under OA. Secondly, it examines the molecular landscape through functional gene expression of OA-tolerant coral phenotypes, identifying key biological mechanisms of resistance. Thirdly, it evaluates the biological end products, calcification and dissolution rates, and their coupling with metabolism, under a full factorial chemical and physiological examination. Synthesizing microenvironmental physical limitations, molecular resistance, and the resulting product of calcification, addressing research questions related to the mechanisms of coral response to seawater acidification. Results here provide direct evidence of physical traits and biomarkers of resistance that, importantly, may be used to characterize coral vulnerabilities to future climate change.