A project undertaken at the School of Life Sciences, University of Technology Sydney and supervised by Dr Katherina Petrou and Dr Daniel A Nielsen
Coral reefs form one of the most magnificent and diverse ecosystems on the planet. As foundation species, reef-building corals are essential to the health and functioning of the ecosystem, providing a valuable food resource and habitat through their structural complexity. Corals are comprised of an animal host and microalgal symbiont that live in a mutually beneficial symbiotic relationship that underpins the success of corals in the nutrient poor waters of the tropics. However, corals live close to their thermal tolerance, making them vulnerable to warming sea temperatures, which can result in a loss of symbionts from the coral tissue, also known as “bleaching”, leaving the coral vulnerable to starvation. With increasing water temperatures due to global warming, mass coral bleaching events is increasing both in frequency as well as in severity, causing a decline in coral reef integrity and cove across the globe. While the process of coral bleaching has been well documented through decades of observations, the underlying physiological mechanism that results in the disruption of the symbiosis during heat stress is not yet fully understood, leaving us blindfolded in our search for means to guard our reefs from the threat of global warming.
Figure 1. Coral colonies collected from Heron Island reef flat before fragmentation
Figure 2. Close up of coral fragments Stylophora pistillata, Acropora millepora and Pocillopora damicornis, in aquaria for thermal stress experiment
Figure 3. Monitoring temperature in coral tanks
Coral bleaching, although often described as an ecosystem wide event, is fundamentally a process occurring at the single-cell scale. For this reason, single-cell techniques are required to effectively separate the response of the different cell-types during the bleaching process. This project aims to resolve the biomolecular fingerprint of host and symbiont cells across different species of corals during the bleaching process using synchrotron-based InfraRed (IR) microspectroscopy. This fast, non-destructive technique can detect variations in biomolecular composition at the single cell level, providing a snapshot of the metabolic state of individual cells. Through this, we aim to elucidate the metabolic “fingerprint” of coral bleaching and thus expose the key physiological changes that occur within the coral leading up to the expulsion of its life-giving symbionts.