MARUM Research Academy

Coral acclimation to global warming: Uncovering the mechanisms of coral-symbiont dynamics and symbiont change (SYMCHANGE)

Hard corals form the foundation of coral reefs. Their success is the result of an endosymbiotic association with photoautotrophic algae (symbiont hereafter). High water temperatures induce corals to expel their symbionts, a phenomenon called bleaching, which is the most prominent threat to coral reef ecosystems. Since some symbionts are more thermally tolerant than others, symbiont change (i.e., a shift of the symbiont community within corals) may constitute an acclimation mechanism of the coral-algae complex under global warming. Trade-offs between increased thermal tolerance at the expense of reductions in key physiological functions, such as coral growth and calcification, pose limitations to this hypothesis. In addition, the physiological mechanisms underpinning symbiont change and the related ability of corals to adapt to thermal stress are poorly understood.

In my doctoral research, I aim to integrate experimental ecology with mathematical modelling to identify the mechanisms and environmental conditions driving symbiont change and to assess its effects on coral functions. While experimental work will be carried out collaboratively, the modelling component will constitute the primary focus of my research. Numerical experiments will allow me to explore different coral acclimation hypotheses related to symbiont change and their effects in the context of varying environmental conditions. The combination of laboratory experiments with mathematical modelling is a promising approach to uncover the processes driving the relationship between corals and different symbionts, the mechanisms at the base of the changing symbiont populations, along with the costs and benefits associated with such changes.