Symbiosis Stability, Pathogens and Reef-Building Corals’ Health: Insights on the Ecology of the Human Body

Abstract

In search of insights for general rules about the host-symbiont-pathogen interaction, a review on the ecology of the interaction between hermatypic corals (Cnidaria: Scleractinia) and their symbiotic zooxanthellae (photosynthetic dinoflagellates, Symbiodinium) is done. In the last three decades a global decline on coral reef barriers has been observed and this has been attributed to, among other causes, two processes that directly interferes in the coral-zooxanthellae interaction: 'coral bleaching' and epidemics. Bleaching events are characterized by a sudden loss of zooxanthellae, commonly leading to mass mortality on coral colonies. Although it is not possible to establish causal relations, the intensities of epidemics and bleaching events are correlated, indicating that the symbiosis is a protective factor on coral's health. Some of the insights for human epidemiology are: the recurrent evolution of pathogens and the interference of symbionts on the host-pathogen interaction, either by direct competition exclusion or by an indirect effect on host's energy budget.