Symbiotic Dinoflagellate Functional Diversity Mediates Coral Survival under Ecological Crisis

© 2017 Elsevier Ltd Coral reefs have entered an era of ‘ecological crisis’ as climate change drives catastrophic reef loss worldwide. Coral growth and stress susceptibility are regulated by their endosymbiotic dinoflagellates (genus Symbiodinium). The phylogenetic diversity of Symbiodinium frequently corresponds to patterns of coral health and survival, but knowledge of functional diversity is ultimately necessary to reconcile broader ecological success over space and time. We explore here functional traits underpinning the complex biology of Symbiodinium that spans free-living algae to coral endosymbionts. In doing so we propose a mechanistic framework integrating the primary traits of resource acquisition and utilisation as a means to explain Symbiodinium functional diversity and to resolve the role of Symbiodinium in driving the stability of coral reefs under an uncertain future. Coral ecosystem health is strongly influenced by Symbiodinium diversity. The ecological success of Symbiodinium cannot be resolved from phylogenetic diversity alone. Traits describing resource acquisition and incorporation capture the functional diversity of Symbiodinium. Symbiodinium species shifts reflect the changing metabolic requirements of the host. Functional diversity will determine the resilience of coral reefs to environmental change