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Warming-Driven Regime Shifts and Rebound Potential in Coral Reefs

Paper Reviewed
Graham, N.A.J., Jennings, S., MacNeil, M.A., Mouillot, D. and Wilson, S.K. 2015. Predicting climate-driven regime shifts versus rebound potential in coral reefs. Nature 518: 94-97.

In an important study published in Nature, Graham et al. (2015) document coral reef responses to the major warming-induced bleaching event of 1998 that caused unprecedented region-wide mortality of Indo-Pacific corals. In a nut shell, they report that "following loss of more than 90% live coral cover, 12 of 21 reefs recovered towards pre-disturbance live coral states, while nine reefs underwent regime shifts to fleshy macroalgae." So what caused the original corals to take these two divergent routes?

The five researchers -- hailing from Australia, France and the United Kingdom -- determined that recovery was favored when reefs were (1) structurally complex, (2) in deeper water, (3,4) the density of juvenile corals and herbivorous fishes was relatively high, and (5) nutrient loads were low, while the reverse of these characteristics typically led to coral demise and macroalgal dominance.

In a commentary on the findings of Graham et al. in the same issue of Nature, Pandolfi (2015) writes that "the fact that more than half of the reefs fully recovered after the bleaching event is a promising outcome for the future of coral reefs," and that "it is also consistent with studies showing that each mass bleaching leaves many sites unaffected, with almost complete recovery of corals from the 1998 event in many parts of the world," citing Baker et al. (2008). And in the final "take-home" message of his commentary, Pandolfi says that "put simply, many reef corals just might be capable of adapting fast enough to survive current rates of global environmental change," additionally citing in this regard the work of Pandolfi et al. (2011) and Munday et al. (2013).

References
Baker, A.C., Glynn, P.W. and Riegl, B. 2008. Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook. Estuarine, Coastal and Shelf Science 80: 435-471.

Munday, P.L., Warner, R.R., Monro, K., Pandolfi, J.M. and Marshall, D.J. 2013. Predicting evolutionary responses to climate change in the sea. Ecology Letters 16: 1488-1500.

Pandolfi, J.M. 2015. Deep and complex ways to survive bleaching. Nature 518: 43-44.

Pandolfi, J.M., Connolly, S.R., Marshall, D.J. and Cohen, A.L. 2011. Projecting coral reef futures under global warming and ocean acidification Science 333: 418-422.

Posted 29 May 2015