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Investigating Acute Montipora White Syndrome in Kāne‘ohe Bay, O‘ahu: Causative Agents, Putative Environmental Drivers, and the Importance of Host Health.

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Title:Investigating Acute Montipora White Syndrome in Kāne‘ohe Bay, O‘ahu: Causative Agents, Putative Environmental Drivers, and the Importance of Host Health.
Authors:Beurmann, Silvia
Contributors:Microbiology (department)
Date Issued:May 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Reports of disease-related coral mortality have increased over the last few decades.
Coral diseases contribute to the decline of coral reefs globally and threaten the health and
future of coral reef communities. There is an imminent need to develop our understanding
of the biotic and abiotic drivers of coral disease outbreaks on an ecological and molecular
level. Montipora white syndrome (MWS) is a tissue loss disease that affects populations of
the coral Montipora capitata in Kāne‘ohe Bay, Hawai‘i. Two types of MWS have been
documented; a chronic progressive tissue loss disease termed chronic MWS (cMWS), and a
comparatively faster infection termed acute MWS (aMWS). Colonies exhibiting cMWS have
been observed to spontaneously switch to aMWS in the field. This dissertation describes
analysis of coral-associated bacterial communities, causative agents of disease, the
importance of host health, and putative environmental drivers that may be promoting
outbreaks of aMWS and the switching of chronic infections to acute lesions. This
investigation of aMWS is described over four chapters. First, the bacterial communities
between healthy and diseased M. capitata colonies were compared during an ongoing
aMWS outbreak versus a non-outbreak period to identify whether a specific shift in
bacterial community structure is associated with this disease. The bacterial communities
were analyzed using high-throughput sequencing and all health states shared different
community compositions with an overall high abundance of Escherichia spp. possibly
originating from sewage contamination. Second, a coral disease treatment method was
assessed to determine whether the removal of cMWS lesions from M. capitata colonies
could reduce morbidity and prevent re-infections. The treatment resulted in an overall
reduction in morbidity and prevented lesions from switching from chronic to acute tissue
loss. Third, to further describe potential causative agents of this disease, bacterial isolates
from diseased M. capitata were screened for virulence using controlled infection
experiments. Isolate OCN003 was identified as an etiological agent of aMWS, and more
readily infected cMWS-afflicted coral fragments than healthy fragments, which is the first
coral pathogen demonstrated to act as a secondary pathogen. Lastly, OCN003 genome was
sequenced and was identified as a novel bacterial species and named Pseudoalteromonas
piratica.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017.
URI:http://hdl.handle.net/10125/62543
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Microbiology


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