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PLoS One. 2015 Oct 28;10(10):e0139223. doi: 10.1371/journal.pone.0139223. eCollection 2015.

Transcriptomic Changes in Coral Holobionts Provide Insights into Physiological Challenges of Future Climate and Ocean Change.

Author information

1
Australian Institute of Marine Science, PMB 3, Townsville MC, Queensland, Australia; School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia.
2
School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland, Australia.
3
School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia; Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America.
4
University of Queensland Centre for Clinical Research, The University of Queensland, Herston, Queensland, Australia.
5
School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia.
6
Global Change Institute and ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia.
7
School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia; Global Change Institute and ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia.

Abstract

Tropical reef-building coral stress levels will intensify with the predicted rising atmospheric CO2 resulting in ocean temperature and acidification increase. Most studies to date have focused on the destabilization of coral-dinoflagellate symbioses due to warming oceans, or declining calcification due to ocean acidification. In our study, pH and temperature conditions consistent with the end-of-century scenarios of the Intergovernmental Panel on Climate Change (IPCC) caused major changes in photosynthesis and respiration, in addition to decreased calcification rates in the coral Acropora millepora. Population density of symbiotic dinoflagellates (Symbiodinium) under high levels of ocean acidification and temperature (Representative Concentration Pathway, RCP8.5) decreased to half of that found under present day conditions, with photosynthetic and respiratory rates also being reduced by 40%. These physiological changes were accompanied by evidence for gene regulation of calcium and bicarbonate transporters along with components of the organic matrix. Metatranscriptomic RNA-Seq data analyses showed an overall down regulation of metabolic transcripts, and an increased abundance of transcripts involved in circadian clock control, controlling the damage of oxidative stress, calcium signaling/homeostasis, cytoskeletal interactions, transcription regulation, DNA repair, Wnt signaling and apoptosis/immunity/ toxins. We suggest that increased maintenance costs under ocean acidification and warming, and diversion of cellular ATP to pH homeostasis, oxidative stress response, UPR and DNA repair, along with metabolic suppression, may underpin why Acroporid species tend not to thrive under future environmental stress. Our study highlights the potential increased energy demand when the coral holobiont is exposed to high levels of ocean warming and acidification.

PMID:
26510159
PMCID:
PMC4624983
DOI:
10.1371/journal.pone.0139223
[Indexed for MEDLINE]
Free PMC Article

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