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Surveys of emergent terraces and U-series ages for ten sites along the coast of East Timor provide estimates of late Quaternary differential vertical strain in the most mature region of the Banda Arc-continent collision complex. Over a distance of ~180 km vertical displacement rates vary between 0.0 and 1.6 meters per 1000 years for the last 150,000 years. Two models of terrace formation (constructional and erosional) are applied to interpret terrace ages from coral ages and to estimate uplift rates. The highest uplift rates are from three sites over a distance of 15 km along the coast. Uplift rates were estimated from corals approximately 20 m above mean sea-level that yield ages of c. 54–74 ka, which correspond to the 3a (c. 49-52 ka) sea-level highstand and a possible highstand or standstill in regression between the 5a sea-level highstand and the 4 sea-level lowstand . These ten sites and resulting variable uplift rates are used constrain a wavelength of deformation due to the fact that recognizable terraces along the coast are not consistent. Terraces cannot be correlated over distances greater than 10 km, vary between 2 to 25 in number, and reach varying altitudes between ~100 and 600 meters above sea-level. The results propose that along an east-west transect a background surface uplift rate increases from 0.1 meter per 1000 years near Subau to 0.5–0.6 meters per 1000 years west of Baucau and remains at that rate for over 170 km. This would indicate a broad wavelength of deformation, possibly related to lithospheric scaled processes. However, superimposed on this background uplift rate is a shorter wavelength (< 15 km) of uplift with a mean of 1.2 meters per 1000 years and peak surface uplift at 1.6 meters per 1000 years. Another interpretation proposes the possibility of at least three shorter wavelength features. The shorter wavelength is likely associated to deformation in the upper crust. This study associates the crustal deformation to Quaternary movement along retro-wedge thrust faults at depth, which indicates active crustal shortening in Timor region.

Human activity since the Industrial Revolution has increased global greenhouse gas concentrations resulting in rapid climate change, which now threatens terrestrial and marine ecosystems. Tropical coral reefs, along with the biodiversity and communities they support, are particularly threatened by these changes in climate. Corals are a consortium of organisms, with the coral host along with its photosynthetic endosymbiont (Family Symbiodiniaceae) and diverse community of microorganisms (bacteria, archaea, fungi, and viruses) together forming the ‘coral holobiont’. However, the symbiosis between tropical corals and Symbiodiniaceae algae is sensitive to even small changes in temperature and ‘coral bleaching’ events – the loss of symbiosis – are now occurring with increased frequency and severity. These bleaching events can result in coral mortality and loss of entire reefs if stressful conditions do not subside. While research efforts have increased our ability to understand and predict coral bleaching events, fundamental questions remain surrounding how genetic diversity of the coral holobiont and interactions with its environment can drive coral resilience or resistance under climate change. The overarching goal of my dissertation is to understand how various abiotic (i.e., stress duration, spatiotemporal variation on the reef) and biotic (i.e., holobiont diversity, symbiosis) factors determine a coral’s response to environmental change at the level of phenotype and genotype. To achieve this goal, I first tested how environmental history and stress duration modulated the physiological responses of two reef-building corals under combined ocean warming and ocean acidification conditions. I found that one species was more stress-resistant (Siderastrea siderea), but that both duration of stress exposure and environmental history (inshore vs. offshore reef origin) modulated coral physiology. Next, I investigated the importance of holobiont genetic identity and abiotic environment in driving phenotypic responses of S. siderea exposed to a diel temperature variability (DTV) and subsequent heat challenge experiment. I found that while DTV increased coral growth, cryptic host diversity and their unique pairings with algal symbiont strains were the strongest predictors of holobiont physiology and response to heat challenge. Lastly, I leveraged genome-wide gene expression profiling and the facultative symbiosis between the subtropical coral Oculina arbuscula and its symbiont Breviolum psygmophilum to disentangle the independent responses of both partners to heat and cold challenges in and out of symbiosis. I found that O. arbuscula host gene expression was more plastic under temperature challenges relative to B. psygmophilum when in symbiosis, and that symbionts exhibited more gene expression plasticity in culture compared to in symbiosis. Taken together, this dissertation provides valuable insights into the phenotypic and genotypic mechanisms that contribute to coral success in a changing climate.

This study sought to connect two bodies of knowledge--integrative complexity and attribution theory. Integrative complexity is a term that indicates the simplicity vs. complexity of a person's mental frame and perceptual skill. A person who perceives nuance and subtle differences typically scores higher on an integrative complexity measure. Attribution theories are concerned with how individuals perceive causation for various events. The limited research into the linkages between perceived causation for an event and how complexly a person thinks about the domain of that event, coupled with the dearth of attribution research in the natural resource management literature, inspired this research. Florida Keys coral reef users were sent a mail questionnaire between July 2009 and March 2010. Integrative complexity level was determined using an index that was developed for this research. Based on attributional and cognitive complexity literature, it was hypothesized that people who score lower in integrative complexity would exhibit an "external" attribution pattern. Integrative complexity was also proposed to influence: attitude and value extremity; number of perceived problem causes; and use of mediated communication. Finally, it was hypothesized that individuals will assign more blame to other groups than to their own. Six of the study's seven null hypotheses were rejected: 1) a significant relationship was found between integrative complexity level and the number of causes that respondents recorded for the decline of the Florida Keys reef ecosystem, 2) significant differences were observed in attitude extremity according to integrative complexity, 3) significant differences were observed in value orientation according to integrative complexity, 4) significant differences were observed in value extremity according to integrative complexity level, 5) significant differences were observed in mediated communication according to integrative complexity level, and 6) significant differences were observed in blame pattern according to group affiliation. Only one null hypothesis was not rejected: no support was found for a connection between integrative complexity and attribution style. These results indicate support for the integrative complexity index, though work to refine the measure seems in order. Additional recommendations for future research include investigating new approaches to examining the relationship between integrative complexity and attribution style.

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.

Microorganisms provide essential services for host organisms and this is especially true for communities of algal symbionts and bacteria hosted by tropical reef-building corals–collectively termed the coral holobiont. Endosymbiotic algae provide essential nutrients to the host, and can impact coral growth and susceptibility to environmental stress. Corals also associate with a diverse microbiome, and specific bacterial taxa have been implicated in important nutritional and immunity roles. However, fundamental questions regarding the environmental factors that govern coral holobiont composition remain unanswered. The overarching goal of my dissertation is to characterize how environmental variation, including disturbance, influences the composition of coral-associated algal and bacterial communities. To achieve this goal, I first compared these communities across reef zones (locales differing in diel thermal variability and other factors) in tandem with host genetic background under baseline conditions. I found that in the more stable reef zone, algal communities were more diverse and that host genetic diversity correlated with bacterial diversity, implying the more variable reef zone constrained diversity of host-microbial partnerships. Next, I characterized how these communities responded to a hurricane disturbance in two stress-tolerant congeneric coral species. Again, I observed stark differences across reef zones in algal symbiont and bacterial communities, but these communities were not exceptionally impacted by disturbance. Finally, I experimentally tested the role of daily thermal variability as a key environmental factor in shaping holobiont community composition and heat tolerance. While thermal variation treatment increased algal photosynthetic efficiency, it did not facilitate coral thermal tolerance to heat stress. Specific bacterial taxa were differentially abundant after 90 days in treatment acclimation, suggesting that thermal variation may contribute to part of the observed community differences across natural reef zones. In sum, this dissertation provides a deeper understanding of the interplay between coral-associated microorganisms and their local reef environments, as well as taxa-specific patterns of interest for monitoring coral holobiont dynamics under rapidly changing oceans.

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