El Niño causes mass coral die-off in Indian Ocean

Researchers have discovered worrying results following a series of climatic changes in 2016.

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Parrotfish

The eastern equatorial warming of the Pacific Ocean, referred to as El Niño, has had a devastating impact on coral reefs.

Researchers discovered that the 2016 rise in sea surface temperatures has caused widespread coral bleaching and extensive coral death in shallow water reef habitats.

The University of Exeter team study focused its investigation in the southern Maldives.  

“The most alarming aspect of this coral die-off event is that it has led to a rapid and very large decline in the growth rate of the reefs,” said professor Chris Perry.

The academic explained that this has major implications not only for the capacity of these reefs to match any increases in sea-level, but is also likely to lead to a loss of the surface structure of the reefs that is so critical for supporting fish species, diversity and abundance.

The abundance of different species along the 3-dimensional surface of the reefs was examined and compared to previous assessments in replicate locations.

The ‘carbonate budget’ (the rate at which corals produce carbonate in relation to the rate it is removed) influences how fast a reef can grow.

The researchers discovered a major decline in this, averaging at a staggering 157 per cent.

Parrotfish, who feed on coral, were found to be eroding the reef at an increased rate since this mass die-off event, meaning the structure of the reef is eroding faster than it is growing.

“A very major concern now is how quickly these reefs might recover. Recovery from similar past disturbances in the Maldives have taken 10–15 years, but major bleaching events are predicted to become far more frequent than this,” said Perry.

Discover 9 facts you didn’t know about El Nino

Read more wildlife news stories in BBC Wildlife Magazine

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