The Chemical and Microbial Ecology of Deep-Sea Corals
Open Access
- Author:
- Vohsen, Samuel
- Graduate Program:
- Biology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 28, 2019
- Committee Members:
- Charles Raymond Fisher, Jr., Dissertation Advisor/Co-Advisor
Roberto Iglesias-Prieto, Committee Chair/Co-Chair
Iliana Brigitta Baums, Dissertation Advisor/Co-Advisor
Tracy Langkilde, Program Head/Chair
Andrew David Patterson, Outside Member - Keywords:
- deep-sea
coral
microbiome
apicomplexans
sulfur-oxidizers
SUP05
chemoautotrophy
Mollicutes
symbionts
metabolomics
metagenome - Abstract:
- Shallow-water corals provide the structure for some of the most diverse communities on the planet and are globally threatened by human activities. Recent research has highlighted the importance that microbes play in the health and resilience of shallow-water corals. Corals in the deep-sea also form diverse and ecologically important communities. However, their microbial associations are poorly understood. The first chapter provides an introduction to deep-sea coral habitats and cold seeps. The second chapter lays the foundation for using metabolomics to study deep-sea corals. It demonstrates that deep-sea coral species exhibit distinct metabolomic fingerprints and produce unique metabolites such as diterpenes. It also shows that deep-sea corals show differences in metabolomic richness between species, between populations of a single species, and between individuals. The last three chapters investigate the microbes that associate with deep-sea corals. Chapter three investigates the occurrence and role of apicomplexans within a broad diversity of corals. Apicomplexans are widespread in deep-sea corals down to 700 m and were even detected down to 1400 m. These apicomplexans possessed plastids that encoded genes involved in the synthesis of chlorophyll but may be repurposed for a role in a parasitic lifestyle. Chapter four reports the association between many corals near seeps and members of the chemoautotrophic SUP05 cluster of bacteria which includes the chemoautotrophic symbionts of mussels from cold seeps and hydrothermal vents. The genome of one of these coral-associated SUP05 phylotype encoded the genetic repertoire required for chemoautotrophy and its relative abundance in Paramuricea sp. type B3 was correlated with chemoautotrophically produced carbon and nitrogen input into the coral holobiont. This suggests that deep-sea corals near seeps may acquire a nutritional supplement from chemoautotrophic symbionts. Chapter five describes the association between novel bacteria of the class Mollicutes and corals in the genus Callogorgia delta. A single mollicute phylotype was abundant and dominant in Callogorgia delta and the closely-related species C. americana. We observed abundant bacteria throughout the mesoglea of the coral which we hypothesize is this mollicute. This mollicute and a less abundant secondary mollicute are divergent from all other known members of the class Mollicutes. The genome of the dominant mollicute was heavily reduced and revealed a dependence on arginine for ATP production however its role within corals is still unclear. This work reveals that a variety of microbes are abundant in deep-sea corals, are likely important to the coral’s health, and may have interactions with their coral host that range from parasitism to mutualism.