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Investigating Coral Disease Spread across the Hawaiian Archipelago.

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Title:Investigating Coral Disease Spread across the Hawaiian Archipelago.
Authors:Sziklay, Jamie M.
Contributors:Zoology (department)
Date Issued:May 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Coral diseases negatively impact reef ecosystems and they are increasing worldwide;
yet, we have a limited understanding of the factors that influence disease risk and
transmission. My dissertation research investigated coral disease spread for several
common coral diseases in the Hawaiian archipelago to understand how host-pathogenenvironment
interactions vary across different spatial scales and how we can use that
information to improve management strategies. At broad spatial scales, I developed
forecasting models to predict outbreak risk based on depth, coral density and
temperature anomalies from remotely sensed data (chapter 1). In this chapter, I
determined that host density, total coral density, depth and winter temperature variation
were important predictors of disease prevalence for several coral diseases. Expanding
on the predictive models, I also found that colony size, wave energy, water quality, fish
abundance and nearby human population size altered disease risk (chapter 2). Most of
the model variation occurred at the scale of sites and coastline, indicating that local
coral composition and water quality were key determinants of disease risk. At the reef
scale, I investigated factors that influence disease transmission among individuals using
a tissue loss disease outbreak in Kāne‘ohe Bay, O‘ahu, Hawai‘i as a case study
(chapter 3). I determined that host size, proximity to infected neighbors and numbers of
infected neighbors were associated with disease risk. Disease transmission events
were very localized (within 15 m) and rates changed dramatically over the course of the
outbreak: the transmission rate initially increased quickly during the outbreak and then
decreased steadily until the outbreak ended. At the colony scale, I investigated disease
progression between polyps within individual coral colonies using confocal microscopy
(chapter 4). Here, I determined that fragmented florescent pigment distributions
appeared adjacent to the disease front of infected coral and had fewer intact polyps
than in healthy coral fragments. These results suggested that disease progression
within colonies affected with chronic and acute Montipora white syndromes are highly
localized rather than systemic and their bacterial pathogens directly attack the coral
tissue rather than zooxanthellae. Overall, my dissertation research indicates that
watershed condition and coral community configuration can facilitate and/or inhibit coral
disease spread, and that disease transmission may be more spatially constrained than
previously thought.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017.
URI:http://hdl.handle.net/10125/62831
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. - Zoology


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