Advisory Committee Chair
Dustin Kemp
Document Type
Dissertation
Date of Award
2024
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Abstract
Corals and other cnidarians maintain complex symbioses that include photosynthetic endosymbiotic dinoflagellates (Symbiodiniaceae), protozoans, fungi, bacteria, archaea, and other metazoans, collectively known as the holobiont. The stability of these associations is crucial for holobiont resilience and adaptation to environmental conditions and are the results of long-term ecological and evolutionary processes. Environmental factors such as light availability, seasonal environmental fluctuations, and warmer, more acidic conditions can disrupt these symbiotic associations and alter holobiont functioning. To understand the influence of different environments on cnidarian host and symbiont physiology, two framework coral species (Acropora palmata and Orbicella faveolata) from nursery-raised and wild populations of the Florida Keys, USA were studied across seasons. The land-based nursery-raised corals exhibited similar seasonal fluctuations in biomass and Symbiodiniaceae densities compared to wild conspecifics but also showed evidence of low light photoacclimation and had significantly lower tissue biomass than wild conspecifics. These results imply that land-raised corals may undergo physiological stress from domestication when transplanted to offshore reefs. To assess this transition from land-based nurseries to coral reef habitats, the physiological acclimatization of A. palmata and O. faveolata was documented after transfer of these corals to nearshore and offshore reef environments. After one year, these corals revealed differential photoacclimation and physiological acclimatization to these reef environments, indicated with changes in photopigmentation, diet composition, and energy reserves of both coral species. Shifts in growth and dominant Symbiodiniaceae associations were also observed in A. palmata corals. Finally, in Palau, Micronesia, I assessed the impacts of warm, acidic environments and human proximity on the stability of coral holobiont associations for five coral species. Stable microbial associations were found in corals across offshore and warmer, more acidic nearshore environments, suggesting long-term holobiont acclimatization. However, corals near human developments exhibited significant shifts in microbial communities, likely impacting innate immunity, nutrient cycling, and disease resistance of these corals. Changing environments are a reality of anthropogenic climate change, which is altering coral reef ecosystems and influencing coral holobiont associations. Therefore, testing the ability of these symbioses to persist and the extent of coral holobiont physiological plasticity provides more informed conservation and management of these ecosystems.
Recommended Citation
Gantt, Shelby, "Environmental Influences On The Physiology Of Cnidarians And Their Symbionts" (2024). All ETDs from UAB. 3868.
https://digitalcommons.library.uab.edu/etd-collection/3868
