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The Non Effects of Ocean Acidification on the Coral Microbial Community

Paper Reviewed
Marcelino, V.R., Morrow, K.M., van Oppen, M.J.H., Bourne, D.G. and Verbruggen, H. 2017. Diversity and stability of coral endolithic microbial communities at a naturally high pCO2 reef. Molecular Ecology 26: 5344-5357.

Writing as background for their study, Marcelino et al. (2017) state that "the responses of the coral microbiome, including both prokaryotic and eukaryotic members, to acidification has gained attention as we continue to uncover vital roles played by micro-organisms in [coral] holobiont health and resilience." Nevertheless, they lament that "little is known about the coral endolithic communities and how these may change under various sea water pH conditions." Thus, it was their purpose to investigate this emerging, yet important, topic.

To accomplish their objective, the team of five scientists used DNA sequencing (high-throughput amplicon; 16S rRNA gene, UPA and tufA) to investigate the effects of ocean acidification (OA) on the diversity and structure of endolithic microbial communities living within the holobiont of corals inhabiting a naturally elevated pCO2 seawater reef site near the Milne Bay Provence of Papua New Guinea. Reefs at this location are in close proximity to volcanic seeps that expel ~99% pure CO2, creating a gradient of seawater pCO2 conditions by which the authors could conduct this study in situ. Analyses of the microbial communities were performed on Porites coral samples collected at average pCO2 values of 998, 624, 368 and 346 µatm.

Results of the DNA sequencing, in the words of the researchers, revealed that the composition of the Porites microbial communities was "virtually unaffected by the surrounding high pCO2 water." According to Marcelino et al., the prokaryotic and eukaryotic members of the microbiome were found to be "highly diverse but indistinguishable between corals inhabiting naturally high pCO2 reefs and ambient conditions," suggesting they are "possibly resilient to OA." Consequently, in light of their important findings, the authors conclude that the coral microbiome is "less likely to be disturbed by OA than we previously thought." And that is more great news for those concerned about the demise of coral reefs in response to OA. It seems that the more these keystone marine species are studied, the more confidence we gain as to their ability to successfully cope with whatever challenges man and nature present them with… ocean acidification included!

Posted 30 May 2018