Impacts of mass coral die-off on Indian Ocean reefs revealed
Warming sea waters - caused by climate change and extreme climatic events - threaten the stability of tropical coral reefs, with potentially
Publisher: The Ecologist
Date Written: 27/03/2017
Year Published: 2017
Resource Type: Article
Cx Number: CX20553
New research by the University of Exeter shows that increased surface ocean temperatures during the strong 2016 El Niño led to a major coral die-off event in the Maldives, and that this has caused reef growth rates to collapse. They also found that the rates at which some reefs species, in particular parrotfish, are eroding the reefs had increased following this coral die-off event.
Coral reefs are formed by the accumulation of coral skeletons (made of calcium carbonate) that builds up over 100's to 1000's of years, forming the complex structures that support a huge diversity of marine life. The so-called 'carbonate budget' of a reef, which represents the balance between the rate at which this carbonate is produced by corals and the rate at which it is removed (by biological or physical erosion or chemical dissolution), influences the development of these structures and how fast a reef can grow.
The effect these combined factors was a major decline in the carbonate budgets of these reefs, with an average reduction of 157%. Before the warming event, the reefs had been in a period of rapid growth, but after the period of higher sea temperatures a negative carbonate budget was recorded at all sites. Put simply, the structure of these reefs is now eroding at a faster rate that it is growing. Based on past studies the researchers suggest that given the severity of the bleaching impacts it may take 10 to 15 years for full recovery to occur.