New scheme launched for 'bleached and dying' coral life

ZSL's Rachel Jones: 'Corals are like the canary in the coalmine'

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Conservationists led by scientists from the Zoological Society of London have launched a new drive to save some of the world's most endangered corals.

The new EDGE Coral Reefs programme lists the most endangered corals and has enlisted scientists around the world to educate local communities on their importance.

The most dire predictions suggest that tropical coral reefs will be all but extinct within the next half a century, with rising sea temperatures posing the greatest threat.

Coral bleaching

Coral reefs are not just beautiful explosions of colour and sea life - they protect coastal communities from storms and the fish and shrimp they sustain feed people the world over.

But the reefs are in immediate danger from a host of sources.

Top of the list is the threat from rising sea temperatures, which results in "coral bleaching". This involves the loss of algae cells called zooxanthellae, which renders the coral unable to photosynthesise.

While the coral can survive temporary spikes in ocean temperature and the resulting bleaching, longer-term temperature rises kill the marine organisms.

Other threats include ocean acidification, as the seas absorb increased levels of carbon dioxide from the atmosphere.

Bleached coral Rising sea temperatures result in "bleached" coral which prevents the organism from photosynthesising

"Corals are hugely threatened by climate change, by things like rising sea temperature which leads to coral bleaching, ocean acidification, increased storm intensity and frequency and then there's also the local pressures which affect the reef," says Catherine Head, who is co-ordinating the EDGE Coral Reefs project from London.

"Things like overfishing, pollution, sedimentation, coastal development. All those things exacerbate the effects of climate change."

Addressing such local pressures, she says, can buy the reefs some time until governments move to address rising atmospheric and air temperatures.

Local interests


  • Elegance coral or Catalaphyllia jardinae has large tubular tentacles which are green with pink tips and a 'zebra' striped oral disk
  • Crisp pillow coral or Anomastraea irregularis has an overall blue-grey or cream colour and its individual polyps are small, numerous and a shade of brown
  • Horastrea coral or Horastrea indica is a hemispherical, colonial species and is pale-brown in colour with blue-grey oral discs
  • Pillar coral or Dendrogyra cylindrus grows in tall cylindrical columns of heights up to 2m giving it a distinctive pillar-like appearance
  • Elliptical star coral or Dichocoenia stokesii is spherical in shape with irregularly shaped corallites
  • Mushroom coral or Heliofungia actiniformis has a flat shape with large, lobed teeth
  • Elkhorn coral or Acropora palmata forms branching 'antler' type colonies which are yellowy-tan in colour with white tips to the branches
  • Parasimplastrea coral or Parasimplastrea sheppardi is a small, encrusting coral which is colourful in appearance
  • Pearl bubble coral or Physogyra lichtensteini is a colonial species that can form 'massive' colonies with a bubble-like appearance
  • Ctenella coral or Ctenella chagius is a brain coral that is endemic to the Chagos Archipelago

Source: ZSL

As part of the new project, a list of the most endangered corals has been compiled, including a "top 10" of threatened coral species.

Unlike the IUCN Red List of Threatened Species, the EDGE list, say its creators, ranks species in both in terms of the threat they face of extinction and in terms of their evolutionary uniqueness.

Such species, they argue, could play a key role in the adaptation of coral populations to climate change.

The project has also enlisted scientists around the globe to research threatened species and to educate local communities on their importance.

According to Rachel Jones, Senior Aquarium Keeper at the Zoological Society of London (London Zoo), the challenge is to convince those who live close to reefs that protecting them is in their interests.

"Tropical reefs are found in places where often population pressures are really really high and where people are poor they rely on the reef for their food.

"So we need to create an environment where it's worth more to the people who live on reefs to keep the reef alive than it is to dynamite fish it or to trawl it for shrimp or whatever."

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