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What is the difference between warm-water reef-building corals and cold-water corals?

Warm-water reef-building corals are the colourful corals that build and grow on reefs speckled with fishes, crabs, and other creatures in shallow sunlit, warm waters. However, over half of all known coral species are actually found around the world in deep, dark, and colder waters, even at depths with no sunlight at all. These are cold-water corals. They are also generally less well-studied, and less well-known. Cold-water corals – also known as deep-sea corals – serve important roles as fish habitat and are hotspots of marine biodiversity.

Which types of coral does this global assessment cover?

The global assessment covers all warm-water reef-building coral species – 892 species, to be exact. Assessments of cold-water corals recently started; 22 species out of a total of more than 4,000 have been assessed so far.

What percentage of warm-water reef-building corals worldwide are threatened (i.e. in the three threatened Red List categories, Vulnerable, Endangered and Critically Endangered)?

Forty-four per cent of warm-water reef-building corals (at least 340 species) are threatened with extinction. According to the Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ Red List, 56 species are Vulnerable (15%), 251 are Endangered (67%), and 33 are Critically Endangered (9%).

If out of 892 assessed warm-water corals, 340 are threatened, why do you say that 44% are threatened?

Essentially, the percentage threatened for comprehensively assessed groups takes into account that some Data Deficient species may also be at risk of extinction.

We are able to calculate the percentage of a species group that is threatened once it has been comprehensively assessed, which we consider to be when there are Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ Red List assessments for over 80% of the group. However, the actual number of threatened species is often uncertain because some species are Data Deficient, which means it is not possible to assign an extinction risk category to these species due to insufficient data. It is not known whether Data Deficient species are actually threatened or not.

The percentage presented above (44%) provides the best estimate of extinction risk for the reef-forming corals, based on the assumption that Data Deficient species are equally threatened as the data sufficient species. In other words, this 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).

More information is available on the .

What is the percentage of warm water reef-building corals worldwide that are Critically Endangered? Ìý

Nine per cent of warm water reef-building corals worldwide are Critically Endangered.

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Also see:ÌýOver 40% of coral species face extinction – Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ Red List - Press release | Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥Ìý