Coral diel rhythms under an integrative approach

Abstract

The circadian rhythm is one of the primary cycles known to dictate the behavior and physiological processes of most forms of life, including corals, which have been shown to have profound fluctuations within a diel cycle. Regarding scleractinian corals, available information is limited in some aspects: (1) these cycles have been studied in only a few species; (2) most of those studies were performed in aquaria; (3) the investigation of coral chronobiology has usually been constrained to genes previously known to be related to diel cycles, indicating the need to explore the coral circadian rhythm on a broader and integrative scale; and (4) current knowledge on diel rhythms during the initial life stages of corals seems to be limited to one species. To further improve the knowledge on coral diel rhythms, this project consists of two experiments. The first will investigate how coral gene expression and microbial community composition vary in 24-hour cycles on azooxanthellate and zooxanthellate corals. Such an integrative approach is expected to generate data that may allow us to understand the influence of each component in the holobiont diel rhythm as a whole. This project will be the first to perform such an experiment in situ, integrating multiple biotic and abiotic aspects. Based on these data and on published studies, diel rhythms will also be investigated during the ontogeny of a coral in a second experiment, assessing when genes related to diel rhythms start to be expressed in such a pattern. Considering that light pollution may disrupt the physiology of corals, the information generated in this project will provide basic information essential for coral conservation in light polluted areas. (AU)