Pleistocene corals more resilient than thought

Posted By Ian Randall on 4th March 2010

A study of fossil corals has provided fresh optimism that reef ecosystems may be better equipped to deal with present day environmental stresses than previously thought. The research, published in the latest issue of Ecology, looked at a time when sea levels had fallen to their lowest known height.


An ancient coral reef. Image credit - Heinrich Harder

The team, from the ARC Centre of Excellence for Coral Reef Studies and the University of Queensland, analysed eight fossil reefs from the Huon Gulf region in Papua New Guinea. During the period in which these corals were alive, the sea had fallen to 120 metres below its present day level – despite this, a broad diversity of species were discovered.

“What we have found suggests that reef systems are able to survive adverse conditions given suitable shallow rocky habitat. An interesting finding of this study is that complex coral ecosystems were maintained during the less optimal periods of low sea level. These may have been critical to the re-establishment of nearby reefs once environmental conditions began to improve,” said paper author Professor John Pandolfi.

The corals did display a different composition when faced with difficult times of low sea levels – notably having a slower growth rate than in periods of high water – but it is hoped that this research will reveal more about how corals adapt to adverse conditions. While sea levels may presently be rising, it may be possible to use this new information to assess what mankind might need to do to mitigate its impact on reef ecosystems – and offer corals the best hope for survival.

Professor Pandolfi commented: “Although it is little asked, the question of where reef species go when faced with extreme environmental situations is highly relevant for understanding their prospects of survival in the future – and what we need to do to give them the best chance.”

“The fossil record shows that reefs have been remarkably successful in surviving large environmental disturbances. However the combination of drastic environmental changes that we’re seeing today, such as degraded water quality, depleted fish stocks, coral bleaching, ocean acidification and loss of habitat are unprecedented in the history of coral reefs. Although this study clearly highlights the resilience of reef ecosystems, it is important not to underestimate the magnitude of the challenges that reefs are currently facing,” he added.

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