Naturally variable habitats or extreme environments provide a glimmer of hope that climate-resilient coral populations exist on coral reefs worldwide. Yet, the mechanisms by which corals have acclimated to current variability and whether this will allow them to resist future changes remains poorly understood. Here, we examined the impact of pCO₂ variability on the reef-building coral Pocillopora damicornis originating from reefs with contrasting environmental histories (variable versus stable) following reciprocal exposure to stable (218 ± 9) or variable (911 ± 31) diel pCO₂ amplitude (μatm) in aquaria over eight weeks. We found that corals from the variable habitat exhibited less intracellular pH (pHi) acidosis and faster pHi recovery rates in response to experimental acidification stress than corals originating from the stable reef slope, suggesting environmental memory gained from lifelong exposure to pCO₂ variability led to an improved ability to regulate acid–base homeostasis. We further explored changes in biomineralization using scanning electron microscopy (SEM) and gene expression via TagSeq, with preliminary results indicating greater corallite diameter and frontloaded genes for stress in P. damicornis  originating from variable habitats. These results suggest that prior exposure to pCO₂ variability may promote more acidification-resilient coral populations in a changing climate.

Primary Presenter: Kristen Brown, University of Pennsylvania (kristen.brown@uq.edu.au)

Authors:

Marcelina Martynek, University of Pennsylvania  (martynek@sas.upenn.edu)

Zoe Dellaert, University of Rhode Island  (zdellaert@uri.edu)

Hollie Putnam, University of Rhode Island  (hputnam@uri.edu)

Katie Barott, University of Pennsylvania  (katiebarott@gmail.com)