The Physiological Mechanisms of Acclimatization in Tropical Reef Corals

Abstract

SYNOPSIS. The ability of scleractinian corals to survive changes that are predicted in the global environment over the next century will lie in their physiological mechanisms of acclimatization. Corals display rapid modifications in behavior, morphology and physiology enabling them to photoacclimate to changing light conditions, a scenario that demonstrates considerable biological flexibility. Here we argue that the acclimatization mechanisms in corals are fundamentally similar to those exhibited by other invertebrate taxa. We discuss protein metabolism as a mechanism underlying acclimatization responses in reef corals, and explore the relationship between protein turnover, metabolic rate, growth rate, and acclimatization capacity. Our preliminary analyses suggest that corals with low growth rates (μCa/mgN/h) and high metabolic rates (μO2/cm2/hr), such as the massive species, acclimatize more effectively than those with high growth rates and low metabolic rates, a feature that is characteristic of branching species. We conclude that studies of protein turnover, combined with temporally relevant investigations into the dynamic aspects of coral dinoflagellate symbioses will provide considerable insight into why corals exhibit such a high level of variation in response to the same environmental challenge. Furthermore, a more detailed understanding of acclimatization mechanisms is essential if we are to predict how a coral assemblage will respond to present and future environmental challenges.