Meeting Abstract
Acclimatization is a non-genetic process by which an individual organism heightens its stress tolerance after exposure to a stressor. Understanding mechanisms by which corals acclimatize is urgent given their large population declines in response to increasing temperatures. There is growing interest in the role methylation changes play in coral acclimatization and phenotypic plasticity. However, because reef-building corals harbor intracellular symbionts (genus Symbiodinium ), discerning the relative contribution of host and symbiont to acclimatization can be difficult. The Caribbean elkhorn coral, Acropora palmata, has an uncomplicated symbiosis: it associates with just one symbiont species (S. ‘fitti’) and most colonies also harbor only one strain of S. ‘fitti’. August of 2014 was the warmest on record for the Florida Keys. By early September 2014, numerous corals species bleached throughout the Florida Keys reef tract. This event provided an unprecedented opportunity to understand whether methylation status contributes to acclimatization and plasticity in reef corals. Initial surveys of Acropora palmata documented a range of bleaching response. This response varied between reefs but also within single, monoclonal stands of A. palmata. Thus, coral clonemates were observed to exhibit different bleaching susceptibilities despite sharing identical (clonal) Symbiodinium communities. Similarly, 16s tag sequencing data failed to provide evidence for a correlation between other microbiome members and the hosts bleaching response. Instead, reduced representation sequencing of the methylated sites within the coral hosts’ genome indicated a role for methylation differences in contributing to host acclimatization. Further study of epigenetic mechanism contributing to coral acclimatization and plasticity are warranted in the light of rapidly changing shallow marine environments.
