Some 44% of the world’s warm-water, reef-building coral species are facing risk of extinction, according to the latest update by the IUCN Red List of Threatened Species. This is a significant increase compared to the last assessment in 2008, when a third were considered threatened.
The latest assessment covers all known coral species that build colorful reefs in shallow, warm waters. In a statement, the IUCN said of the 892 coral species reassessed recently, at least 340 were found to be threatened. These include 56 species categorized as vulnerable, 251 as endangered and 33 as critically endangered.
The IUCN also took into consideration that some coral species classified as data deficient (DD) could be at risk of extinction, according to an emailed statement from the IUCN’s Coral Specialist Group that referenced a newly published FAQ. “This [44%] is a mid-point figure within a range from 38% threatened species (if all DD species are not threatened) to 51% threatened species (if all DD species are threatened),” the group, which led the coral assessment, said in the statement.
Among species whose conservation status worsened from vulnerable to critically endangered is the saffron coral (Porites sverdrupi), found in the Gulf of California, Mexico. Considered to have a “narrow thermal tolerance,” its population has declined by more than 90% since the 1990s due to hurricanes and bleaching events. The Chagos brain coral (Ctenella chagius), found in the Chagos Islands in the Indian Ocean, also saw its status decline from endangered to critically endangered. While it was common in the 1970s, its population crashed twice in the last three decades due to bleaching and reduction of habitat.
An assessment of cold-water corals found in deeper waters, which comprise more than half of known coral species, is still ongoing. Cold-water corals are at risk from threats such as bottom trawling, oil and gas drilling, laying of undersea cables, and the prospect of deep-sea mining.
“Healthy ecosystems like coral reefs are essential for human livelihoods — providing food, stabilising coastlines, and storing carbon. The protection of our biodiversity is not only vital for our well-being but crucial for our survival,” IUCN director-general Grethel Aguilar said in the statement.
She called for “bold, decisive action to cut greenhouse gas emissions … to secure a sustainable future for humanity.”
Beth Polidoro, coordinator of the IUCN’s Coral Red List Authority, added that both greenhouse gas emissions and local threats should be addressed for the survival of coral reefs.
“By acting now, we can slow the pace of ocean warming and broaden the window of opportunity for corals to potentially adapt and survive in the long term,” Polidoro said in the statement.
The IUCN’s Coral Specialist Group noted that more research is needed to look into how corals can adapt to warmer waters.
Banner image of clownfish and coral reef in Indonesia, by Rhett A. Butler/Mongabay.
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