The Good, the Bad, and the Ugly: Assessing Reef Health and Coral Diseases through Associated Microbes and Host Response

Open Access
- Author:
- Closek, Collin John-erik
- Graduate Program:
- Biology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 08, 2014
- Committee Members:
- Monica Medina, Dissertation Advisor/Co-Advisor
Charles Raymond Fisher Jr., Committee Chair/Co-Chair
Jennifer Macalady, Committee Member
Moriah Louise Szpara, Committee Member - Keywords:
- coral reef health
transcriptomics
bacteria
disease dynamics
Caribbean
Central Pacific - Abstract:
- Coral reefs are one of the most productive and biologically diverse ecosystems; however, over the last 50 years the health of these ecosystems has drastically declined. Corals have symbiotic algae and other associated microbial organisms, which collectively contribute to and comprise the coral holobiont. As an integral part of the coral holobiont, bacteria are used as indicators of coral health. Yet, little is known regarding the bacterial diversity associated with coral reef environments, and even less has been published about the bacteria that are associated with isolated marine protected areas, such as the Papahānaumokuākea Marine National Monument (French Frigate Shoals, Northwestern Hawaiian Islands). To obtain a baseline, both sediment and water-associated bacteria were examined from select locations in the French Frigate Shoals. Other reef locations have also received legal protection, however many corals within protected areas still exhibit strong signs of disease (e.g. such as Puerto Morelos National Marine Park and the Virgin Islands National Park). Minimal research has been published on the bacterial diversity associated with diseased corals. To that end, we examined the bacterial communities associated with Orbicella faveolata exhibiting signs of Yellow Band Disease (YBD) within the Puerto Morelos National Marine Park, Mexico. Additionally, while studies have examined how changes in sea surface temperatures affect the coral-host at the gene-level, gaps remain regarding how corals respond to disease. We explored these gaps by examining the host transcriptomic response to YBD in Mexico and subsequently sampled an additional disease affecting O. faveolata, White Plague, as well as two diseases affecting Acropora palmata in the US Virgin Islands, White Band and White Pox. Of the four diseases examined, core responses across as well as within both species were detected. Differences in host response were also noted between each disease. Profiling the bacterial associations and host response allows us to gain a better understanding of the bacterial diversity associated with different health states of coral reef environments and how the host transcriptome responds to changes in health. These findings may be useful as baselines to diagnose the health state of other declining reef environments.