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Coral Reefs Are Increasingly Threatened by the One-Two Punch of Cyclones and Bleaching

A damaged section of the Great Barrier Reef off Australia's northeastern coast.

A broken part of the Great Barrier Reef off Australia’s northeastern coast.

Before local weather change triggered more and more frequent and lethal coral bleaching occasions, cyclones posed one of the largest threats to the health of the Great Barrier Reef.

Scientists estimated that, previous to 2016, destruction from tropical hurricanes was chargeable for between a 3rd and almost half the loss of coral cowl on the world’s largest reef system over the earlier 30 years, in response to a brand new study revealed in the journal Scientific Reports. Coral bleaching, on the different hand, had contributed solely between 5 % and 10 % of coral loss.

That all modified two years in the past when the first of two unprecedented back-to-back bleaching occasions struck the 1,400-mile-long Great Barrier Reef, in the end killing half its corals (and devastating different tropical reefs worldwide). The new research analyzes how corals have recovered from a mixture of cyclones and bleaching occasions over the previous 19 years in the Palm Islands Group, a set of fringing reefs in the central part of the Great Barrier Reef.

The conclusion: 47.eight % of the research websites’ laborious coral cowl has been misplaced since 1998 and the composition of the reef ecosystem has been dramatically altered. That was mainly attributable to a 1998 bleaching occasion and Cyclone Yasi, a Category 5 storm that scored a direct hit on the reefs in 2011. (The 2016 bleaching occasion hit the northern part of the Great Barrier Reef the hardest, leaving the Palm Islands Group in the central part comparatively unscathed. The affect of the 2017 bleaching occasion will likely be revealed in a forthcoming paper.)

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