Caribbean coral reefs could be gone in 20 years

Caribbean reefs are under threat from the loss of algaegrazing sea urchins and fish. Picture: AFP/Getty Images

Caribbean corals have declined by more than half since the 1970s, mainly due to the loss of parrotfish and sea urchins which graze on the reefs, a new report shows.

But restoring parrotfish populations and protecting reefs from overfishing and excessive coastal pollution could help reefs recover and make them more resilient to the impacts of climate change, the experts said.

The report, by the Global Coral Reef Monitoring Network, the International Union for Conservation of Nature (IUCN) and the United Nations Environment Programme (UNEP), analysed more than 35,000 surveys at 90 Caribbean locations since 1970.

The experts said that, while climate change – long thought to be the main culprit in coral degradation – posed a serious threat by making the seas more acidic and causing bleaching of corals, the main cause of decline has been the loss of grazing creatures.

Sea urchins suffered a mass die-off from an unidentified disease in 1983 and over-fishing has pushed parrotfish to the brink of extinction in some areas.

A loss of these marine creatures has upset the natural balance of the reefs and allows algae on which they feed to smother the coral, the experts said.

Some of the healthiest reefs in the Caribbean are those that harbour large populations of parrotfish, such as the US Flower Garden Banks National Marine Sanctuary in the Gulf of Mexico and Bermuda, which have banned fishing that harms parrotfish. But reefs where parrotfish are not protected have suffered major declines, such as in the US Virgin Islands and Jamaica.

Carl Gustaf Lundin, director of IUCN’s global marine and polar programme, said: “The rate at which the Caribbean corals have been declining is truly alarming.

“But this study brings some very encouraging news: the fate of Caribbean corals is not beyond our control and there are some very concrete steps that we can take to help.” Reefs which are protected from overfishing, as well as coastal pollution, tourism and coastal development are more resilient to climate change, the report said.

Ayana Johnson, of the Waitt Institute’s Blue Halo Initiative – which is collaborating with Barbuda in the development of its marine management plan – said: “Barbuda is about to ban all catches of parrotfish and grazing sea urchins, and set aside one third of its coastal waters as marine reserves.

“This is the kind of aggressive management that needs to be replicated regionally if we are going to increase the resilience of Caribbean reefs.”

The Caribbean is home to 9 per cent of the world’s coral reefs, which generate £1.75 billion annually from tourism and more than a hundred times that in other goods and services, on which 43 million people depend for their livelihood, the experts said.