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Potential Effects of Ocean Acidification on Crustose Coralline Algae

Paper Reviewed
Nash, M.C., Uthicke, S., Negri, A.P. and Cantin, N.E. 2015. Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, Porolithon onkodes, in an experimental system. Biogeosciences 12: 5247-5260.

Nash et al. (2015) begin their work by noting "there are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification," as will the dolomite found within the CCA cells. Therefore, using fragments of live P. onkodes collected from the upper crests of the Great Barrier Reef's Davies Reef, they assessed their concerns using the experimental system employed by Uthicke et al. (2013), where the CCA and dolomite samples were maintained in seawater exposed to three different atmospheric CO2 concentrations (444, 676 and 904 ppm).

And what did the four Australian researchers thereby discover?

They report that (1) "there was no significant effect of CO2 on mol% MgCO3 in any sample set," indicating (2) "an absence of a plastic response under a wide range of experimental conditions," and they further report that (3) "dolomite within the CCA cells formed within 3 months," and that (4) "dolomite abundance did not vary significantly with CO2 treatment."

As for what these several findings portend about the future, Nash et al. confidently conclude that "reef-building P. onkodes will continue to form stabilizing dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution."

Uthicke, S., Pecorino, D., Albright, R., Negri, A.P., Cantin, N., Liddy, M., Dworjanyn, S., Kamya, P., Byrne, M. and Lamare, M. 2013. Impacts of Ocean Acidification on Early Life-History Stages and Settlement of the Coral-Eating Sea Star Acanthaster planci. PLoS ONE 8: 10.1371/journal.pone.0082938.t005.

Posted 15 January 2016