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Great Barrier Reef Corals: Their Past Foreshadows Their Future

Paper Reviewed
Felis, T., McGregor, H.V., Linsley, B.K., Tudhope, A.W., Gagan, M.K., Suzuki, A., Inoue, M., Thomas, A.L., Esat, T.M., Thompson, W.G., Tiwari, M., Potts, D.C., Mudelsee, M., Yokoyama, Y. and Webster, J.M. 2014. Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum. Nature Communications 5: 10.1038/ncomms5102.

In an article published in Nature Communications, Felis et al. (2014) write that "tropical south-western Pacific temperatures are of vital importance to the Great Barrier Reef (GBR)," but they say that the "role of sea surface temperatures (SSTs) in the growth of the GBR since the Last Glacial Maximum remains largely unknown." Thus, they went on to develop records of both Sr/Ca and 18O for U-Th dated fossil shallow-water corals along the shelf edge seaward of the modern GBR for this period of time (20,000 to 13,000 years ago), which data were indicative of a considerably steeper meridional SST gradient than that of the present in the central GBR. More specifically, they found a 1-2°C larger temperature decrease between 17 and 20°S during that time period, which they say "is best explained by the northward expansion of cooler subtropical waters due to a weakening of the South Pacific gyre and East Australian Current."

The fifteen researchers say their findings indicate that "the GBR has experienced much larger SST changes - both spatially and temporally - since the Last Glacial Maximum than previously recognized." And "combined with evidence for the existence of extensive reefs along the shelf edge seaward of the modern GBR at that time," as reported by Webster et al. (2011) and Abbey et al. (2011), they say their results "provide new insights into the ability of coral reefs to adapt to temperature change." And among these insights was their discovery of the apparent resilience of the GBR Isopora coral reef community throughout much of the last deglaciation, in spite of the substantial increases in SSTs they detected.

In light of these findings, Felis et al. concluded their paper by saying "this apparent resilience further suggests that, considering temperature alone, southward expansion of this robust reef crest community could be an important response to future climate warming."

References
Abbey, E., Webster, J.M. and Beaman, R.J. 2011. Geomorphology of submerged reefs on the shelf edge of the Great Barrier Reef: the influence of oscillating Pleistocene sea-levels. Marine Geology 288: 61-78.

Webster, J.M., Yokoyama, Y. and Cotteril, C. plus the Expedition's 325 Scientists. 2011. Proceedings of the Integrated Ocean Drilling Program. Management International Inc., Washington, D.C., USA.

Posted 4 November 2014