Thursday, October 1, 2009

Coral reefs in a thermal crisis

Coral reefs were among the systems hardest hit by the end-Triassic events. Volcanism associated with the breakup of Pangaea released enormous amounts of CO2 into the atmosphere. The increased greenhouse effect and the acidification of the oceans caused a widespread extinction. The large and highly diversified reefs of the Triassic disappeared. One of the few survivors was a reef situated in what today is the south of France.

Wolfgang Kiessling of the Museum für Naturkunde Berlin (Berlin Museum of Natural History) and co-workers went at answering the question why this particular reef survived the extinction event and what lesson can be learnt for estimating the effects of the current environmental change through elevated atmospheric CO2 levels. The surviving European reefs later formed the nucleus for the re-radiation of corals. The recovery, however, took a very long time: 15 million years.

In their work, published in the latest issue of Palaios, they come to the conclusion that the reef was situated in deep shelf waters at high latitudes in a region that had been a hotspot of coral reefs already through the Triassic. Their findings also highlight the importance of deep shelf regions for the survival of marine species. It is not always necessarily remote ocean islands.

Kiessling W., Roniewicz E., Villier L., Léonide P., Struck U. 2009. An early Hettangian coral reef in southern France: Implications for the end-Triassic reef crisis. Palaios, 24: 657-671. doi:10.2110/palo.2009.p09-030r

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