Ecology of the coral Stylophora pistillata inhabiting extreme reef flat habitats of the central Red Sea

Student thesis: Doctoral Thesis


Coral reefs are threatened due to anthropogenic stressors, especially due to warming. Corals typically live in a narrow range of environmental conditions; however, some individuals are able to thrive in extreme temperatures. Such colonies could provide insight into how the coral holobiont acclimates or adapts to extreme temperatures. This study used the model coral species Stylophora pistillata (Esper, 1797) in the Saudi Arabian Red Sea, which is abundant and occurs across a range of desired microhabitats to examine the role of the environment on population structure and physiology. Specifically, this project aimed to 1) review the literature on S. pistillata used in stress studies to better understand the threats it faces, and where knowledge gaps exist, 2) conduct a demographic assessment of S. pistillata populations across different reefs and microhabitats, and 3) evaluate the physiological state of S. pistillata colonies occurring in these microhabitats with differing temperature profiles. The literature review revealed disparities in stress studies on S. pistillata, with most originating from the Gulf of Aqaba and conducted on temperature tolerance. The population assessment showed a high spatial variability in size structure, but a tendency for offshore reefs to have larger colonies and higher colony density. It also showed that purple color morphs tended to be more frequently encountered in the exposed reef flat zones. Similarly, the physiological study showed high spatial variability in chlorophyll, protein and lipid content, and skeletal and symbiont density. However, there was a clear seasonal component, with a multivariate analysis revealing the coolest sampling period as distinct. The metabolic profiles of S. pistillata indicated that offshore colonies differ from midshelf and nearshore colonies. Finally, an opportunistic study reports a case of S. pistillata bleaching due to an unusual occurrence of cold stress coupled with a low tide, supporting the notion that continued monitoring of this population on the reef flat is important for documenting rare evets and understanding their impacts on coral ecology. Taken together, this thesis establishes baseline information on the ecology of an important Red Sea coral inhabiting an extreme environment, and will be important for understanding its response to future changes.
Date of AwardNov 2022
Original languageEnglish (US)
Awarding Institution
  • Biological, Environmental Sciences and Engineering
SupervisorMichael Berumen (Supervisor)


  • Climate Change
  • Stylophora pistillata
  • Coral Reefs
  • Bleaching
  • Physiology
  • Extreme Habitats

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