A conservation assessment of all 845 species of reef-building coral, coordinated by the Global Marine Species Assessment (GMSA)
, showed that one-third of reef-building corals are threatened with extinction (Carpenter et al. (2008) One-Third of Reef-Building Corals Face Elevated Extinction Risk from Climate Change and Local Impacts. Science 321, 560-563).
32.8% of reef building corals fell into the IUCN's threatened categories (Critically Endangered, Endangered, Vulnerable), while 141 species were assessed as Data Deficient.
303 species (52%) are highly susceptible to bleaching, caused by the stress-induced expulsion or death of the symbiotic algae. Many populations recover within a few years of the bleaching event, but only 80 species are considered resistant to bleaching.
Some corals are also heavily impacted by disease and predation from the crown-of-thorns sea star Acanthaster planci (photo).
Acroporid corals account for a high percentage of coral cover on reefs and a high proportion of the threatened species.
Extinction risk may be further exacerbated by local-scale anthropogenic disturbances from fisheries, human development, pollution from agriculture and industry, domestic pollution, and human recreation and tourism activities. The picture shows fishermen pulling in a beach seine net.
The Caribbean has the largest proportion of corals in high extinction risk categories while the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk.
Climate change exacerbates the threat to corals – continued changes in climate can thus affect the geological structure of reefs and their coastal protection function, as well as the food security for the millions of people globally, who are dependant on reef fish.
