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Coral reefs submerged by rising sea levels could leave coastal communities more exposed

21 Jun 2018

Coral reefs are appreciated for their beauty and great diversity of species, but they also provide important services of vast economic value, for example by acting as natural breakwaters, protecting coastal communities from storms. Coral bleaching caused by warming oceans is a well-known threat to coral reefs, that together with other environmental stresses have caused large-scale degradation of corals globally.

Rising sea levels is another threat to coral reefs, and though corals have the capacity to grow vertically in response to increased water depths, the many environmental stresses on coral reefs today may counteract that. In the cover story of this week’s issue of Nature, ASE research fellow Dr. Kyle Morgan and co-authors present the results of a large study of the response of coral reefs to sea level rising, and it’s not good news.

The researchers estimated the potential for vertical growth in over 200 coral reefs in the western Atlantic and Indian Oceans, and then compared that to two different scenarios of regional sea level rise, one conservative and one more pronounced. Their calculations show that though coral reefs have the capacity to track rising sea levels with vertical growth, without continuous ecological recovery of the reefs, most of them will become submerged by 2100. Out of the 200 coral reefs studied, only 9% are in a state to keep up with conservative estimates of sea level rise.

For reef-fronted coastal areas and small island communities in particular, this is really bad news. While assessing coral growth in the small island nation of the Maldives, Dr. Morgan witnessed a 90% decline in productive coral following a massive bleaching event in 2016, showing how sensitive reef ecosystems are. The loss of these coral reefs means a loss of natural coastal protection and potentially greater coastal erosion. The only way to reverse this trend, Dr. Morgan and colleagues point out, is urgent action to slow down the rate of global warming.

Dr. Kyle Morgan is currently studying coral reefs near Singapore within the NRF's Marine Science Research and Development Programme.

Read the Nature article here
Read a Nature News and Views article here