Characterization and Oil Response of the Deep Sea Coral-associated Microbiome
Open Access
- Author:
- Dannenberg, Richard Pierce
- Graduate Program:
- Biology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- December 04, 2015
- Committee Members:
- Iliana Brigitta Baums, Thesis Advisor/Co-Advisor
Charles Raymond Fisher Jr., Thesis Advisor/Co-Advisor - Keywords:
- oil exposure
deep-sea
Leiopathes glaberrima
microbiome
transcriptome
high-throughput sequencing
Illumina
bacteria - Abstract:
- Corals form habitats with high biodiversity, including a diverse microbiome, but we know relatively little about the microbes associated with deep-sea corals. Deep-sea corals are increasingly being exposed to anthropogenic impacts, including oil spills. Although acute effects of oil have been studied in the octocoral Paramuricea biscaya, we know little about the sub-lethal effects, or the effects on hexacorals. The microbiome of these corals is unexplored and may play important roles based on studies of shallow-water corals. Bacterial RNA was collected from 4 colonies (2 red and 2 white) of the black coral Leiopathes glaberrima, and these colonies were exposed to oil over the course of 3 experiments. Recovered genes were classified by primary function and those included nitrogen metabolism and oxidation/reduction. However, only 1,342 bacterial genes were recovered. None of these genes showed any significant differences in expression levels between either red and white corals or oil and control samples. Bacterial community composition was also measured in L. glaberrima collected from 3 sites separated by 375 km in the Gulf of Mexico and compared with 3 other genera of corals: Sibopathes, Lophelia, and Paramuricea. L. glaberrima oil and control samples were also compared from each of the 3 experiments. None of the 3 oil experiments showed any significant differences between oil and control fragments. Proportions of known oil-degrading genera were also examined for each experiment, but showed no significant differences between oil and control samples in any experiment. L. glaberrima harbored a specific microbial consortium that differed from other coral species, water samples, and sediment samples, and also varied within L. glaberrima by site. One operational taxonomic unit (OTU) in particular from the genus Endozoicomonas was found in every L. glaberrima sample. This genus has also been reported as a symbiont in shallow water corals, as well as being found in other marine organisms including sponges. This study lends support to the idea that corals have species-specific assemblages of bacteria that differ from water and sediment reservoirs, and hints that at least a few of them may be important to the coral host.