Coral reefs are the proverbial rainforests of the ocean, but these spectacular structures are
under threat from globally rising sea surface temperatures and ocean acidification. The Red
Sea and the Persian/Arabian Gulf (PAG) display unusually high sea surface temperatures,
and therefore, provide a model for studying environmental change. Corals are so-called
holobionts consisting of the coral host, photosynthetic algae (Symbiodiniaceae), along with
other microorganisms, such as bacteria, archaea, fungi, and viruses. While the importance of
bacteria to coral holobiont functioning is acknowledged, little is known about changes in the
microbial communities under natural environmental stressors in the Red Sea and the PAG.
Accordingly, I investigated microbial community and mucus differences in bleached, healthy,
and diseased corals. Analysis of the composition of mucus-associated microbial communities
of bleached and healthy Porites lobata colonies from the Red Sea and the PAG were stable,
although some regional differences were present. In a distinct study investigating coral
disease, a broad range of corals in the Red Sea were shown to be infected with black band
disease (BBD). Investigating the microbial community associated with BBD revealed the
presence of the three main indicators for BBD (cyanobacteria, sulfate-reducing bacteria
(SRB), and sulfide-oxidizing bacteria (SOB). Last, I investigated the chemical composition
(carbohydrates) of the surface mucus layer of a range of Red Sea corals. Given that coral
mucus represents a first line of defense, I was interested to examine whether mucus
carbohydrate composition would point to a role of adaptation to the extreme environment of
the Red Sea. This analysis showed that mucus consists of conserved sugars that are globally
conserved. In summary, this thesis characterizes the microbial communities associated with a
range of coral species in different health states (bleached, healthy, and diseased). The
microbial community patterns I characterized support the notion that bacteria contribute to
coral holobiont health and possibly adaptation to extreme environmental conditions in the
Red Sea and PAG.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/630144 |
| Date | 11 1900 |
| Creators | Hadaidi, Ghaida A. |
| Contributors | Voolstra, Christian R., Biological and Environmental Sciences and Engineering (BESE) Division, Daffonchio, Daniele, Saikaly, Pascal, Thurber, Rebecca Vega |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2019-12-04, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2019-12-04. |
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