Coral reefs are among the most diverse marine ecosystems, but they are threatened by climate change. The foundation of reef ecosystems is the coral holobiont or metaorganism that consists of the coral animal host, photosynthetic microalgae, bacteria, and viruses (among other organisms). While microalgae provide the energy for corals to build the massive three-dimensional skeletons, bacteria support functions related to metabolism, immunity, and environmental adaptation. Conversely, the function of viruses is less well understood. Although viruses were previously associated with coral disease and bleaching, we are missing an overall understanding of the diversity and identity of viruses associated with corals, in particular for understudied areas such as the Red Sea. Here we characterized coral-associated viral community composition using a large metagenomic and metatransciptomic dataset covering > 1 billion sequences across > 100 coral samples collected from 14 different coral species in the central Red Sea. The viral sequence portion shows that coral species significantly differ from each other, but the most abundant viral families were consistently present. Notably, we found a pervasive abundance of Baculoviridae in metagenomes. In contrast, Polydnaviridae were the most abundant viruses in metatranscriptomes, highlighting that the combined approach of metagenomics and metatranscriptomics is informative with regard to deciphering viral diversity and activity. Our study provides a first comprehensive description of viruses associated with Red Sea corals. In line with previous studies, we confirm the presence of Baculoviridae, Polydnaviridae, Phycodnaviridae, Mimiviridae, and Herpesviridae, which may be considered viral families that are globally and commonly associated with corals. The reason for the pervasive abundance of Baculoviridae in Red Sea corals at present remains unknown, but it is tempting to speculate that the association is related to the uniquely warm and salty environment of the Red Sea.

Mg/Ca and d18O derived from marine biogenic carbonates have been widely used as reliable paleoenvironmental proxy for seawater temperature, salinity and water mass circulation reconstructions. The use of Mg/Ca is based on long residence time in seawater and uniform distribution with habitat depth of planktonic foraminifera. Fluid Mg/Ca affects mineralogy of CaCO3, thus high seawater Mg/Ca favors precipitation of aragonite instead of calcite. The records of d18O in carbonates yield strong correlation with seawater temperature, salinity and d18O. Distribution of d18O in water is highly heterogeneous within longitude, latitude and depth. Therefore a combination of foraminieral d18O and Mg/Ca could resolve temperature, d118Owater, and hence salinity, which is linked to variability in fresh water balance and glacial ice volume throughout geologic history. In this work we study the effects of important seawater/fluid parameters on Mg/Ca in inorganic and d18O in natural samples and provide data for improving paleoceanographic reconstructions.

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The built environment has largely separated itself from the natural one, making demands of nature, and requiring the natural environment to exist on its terms. This prevailing condition has led to the detriment of the natural environment and consequently, those who must inhabit both. Because of this, a shift from the domination of the natural environment to reconciliation with it is necessary. Serving as an intermediary between these two worlds, architecture has the potential to blur the boundaries once created by the built environment in the pursuit of reconciliation. Architecture can learn from the natural environment and take that which has been poorly adapted to aim for a more synchronous future. Shaping culture and perspective, architecture can serve as a signal to humanity that this reconciliation is worth pursuing. This thesis explores the dialogue between form and facade to comment on architecture's flawed yet hopeful path as it seeks a more sustainable relationship with nature. / Master of Architecture / The facade acts as an element of nature, attaching itself to the building like a mask as if it were nature itself taking over the building. Composed of coral-inspired ceramic pieces, the facade hosts an alternative green wall of algae. An otherwise typical rectilinear building form transforms itself, stretching certain spaces beyond its bounds to reach out to the facade as if a reconciliation is desired. This thesis explores the dialogue between form and facade to comment on architecture's flawed yet hopeful path as it seeks a more sustainable relationship with nature.

A diversity of human-assisted approaches to rehabilitate and boost coral health have been suggested and investigated throughout the past years. Vitamins and trace-metal supplementation is a well-known strategy in human medicine and aquaculture, but vitamin addition is not currently actively tested for coral growth and recovery. These molecules are essential cofactors that have been correlated with coral thermal resistance and upregulated in corals treated with beneficial microorganisms (i.e., probiotics). To assess the effects of B12, B6 and zinc supplementation on coral health, we conducted a 2-month experiment in an open-closed-loop system mesocosm joined to a peristaltic pump continuously dosing the vitamins and/or zinc to individual 250 L tanks. Fragments of five different colonies of Acropora hemprichii were randomly distributed into the respective treatment tanks (B12, B6, zinc, multi-treatment and control). After 21 days, the corals were exposed to a pulse (1 day) of thermal stress, followed by three weeks of recovery. Substantial mortality (55%) in the control treatment was observed during the stress and recovery, with B12, B6, zinc and multi treatments exhibiting significantly less mortality (<20%). Coral health data combined with analysis of microbiome and metabolomic approaches suggest that both vitamins and zinc have a positive effect on coral health recovery. This study is the first to provide evidence that complex B-vitamins accompanied by zinc supplementation, can be a valuable tool for coral reef rehabilitation, and paves the way to further understanding specific mechanisms by which these nutrients promote coral health will be needed.

As coral reefs decline globally, there is an urgent need to understand recovery pathways and trajectories to both assess reef status and intervene with reef restoration efforts. However, the ecological role of various coral taxa on reef successional pathways is poorly understood. Building on terrestrial successional frameworks, it seems logical that weedy coral species may be placeholder species that quickly colonize cleared areas after a disturbance, but that are later replaced by more competitive, slower-growing species, leading to overall more biodiverse reefs. To test the competitive ability of a common pioneer species on Pacific reefs, Montipora aequituberculata, we tracked about 600 colonies across six equatorial islands through two time points (50 colonies per site per island), examining whether this species was more typically overgrown by other species over time, or whether M. aequituberculata was a more dominant competitor capable of overgrowing other reef taxa. Using photogrammetric data, we set out to answer questions about the fates of focal colonies and their place in the competitive hierarchy. Trajectories of area change of the focal colonies varied across islands, though they did not follow geographic patterns. Many of the changes in these post-disturbance reefs sometimes differed by site, even on the same island, and were not consistent within an archipelago. At an island scale, Howland (Phoenix Islands) and Flint (Line Islands) showed the greatest growth of focal colonies, while Enderbury (Phoenix) and Millennium (Line) lost the most coral coverage of focal colonies. Interactions between the focal colony and other coral species were more consistent across islands, with the most common interactions being with other colonies of M. aequituberculata as well as common species of Porites and Pocillopora. There was a consistent trend of focal colonies mostly being overgrown by other colonies of M. aequituberculata: this conspecific replacement suggests that this species is capable of self-perpetuating as a primary space holder in lieu of other coral interactions. In contrast, most other coral species were commonly overgrown by the focal M. aequituberculata, suggesting that M. aequituberculata is a strong competitor when vying for groundcover. Indeed, M. aequituberculata may be able to dominate reefs post-disturbance until stress-tolerant species take over. Surprisingly however, we did not see a consistent pattern of species interaction, meaning that there was not a single coral taxon that universally overgrew M. aequituberculata, suggesting that M. aequituberculata is a generalist competitor and is not a specialized facilitator of any one competitively dominant taxa. Islands with similar species interaction patterns are not the same islands with similar growth or loss patterns, suggesting that site-level ecological complexity overrules any general patterns of geography or species interactions. This study is among the first to provide detailed species interactions in a successional framework, paving the way for future studies to do the same in the hopes that we can predict the trajectory of reefs based on the community composition.

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