Disaster on the coral reef

It might look like a tropical paradise, but underneath the sparkling blue waves something truly grim is happening in the Caribbean. Four-fifths of the coral on Caribbean reefs has disappeared in the past 25 years in a phenomenal saga of destruction, British-based researchers have revealed.

Human actions are almost certainly responsible for most of it. And the size of the loss, the first to be accurately quantified over a wide area anywhere, has astonished even scientists who have been studying the global decline of coral.

Coral reefs are thought of as "the rainforests of the sea" because of their richness in wildlife, and the figure is equivalent in marine terms to saying that 80 per cent of the Amazon rainforest has disappeared.

The rate of coral loss is higher than that of rainforest destruction. There has been nothing like it in the past few thousand years, according to the study, which is published in the journal Science.

The work was carried out by researchers at the University of East Anglia and its associated Tyndall Centre for Climate Change Research, using data from 263 Caribbean sites, from Mexico to Barbados, from Cuba to Panama, from the Florida Keys to Venezuela. It mirrors similar concerns from other coral areas including Australia's Great Barrier Reef.

"We report a massive region-wide decline of corals across the entire Caribbean basin," the five-strong team says in the introduction to the paper, in language remarkably strong for a peer-reviewed scientific journal.

Although the report is mainly focused on the extent of the decline rather than its causes, the reasons behind it are principally human, said the team leader, Dr Isabelle Cote, a French-Canadian specialist in tropical marine ecology. They include industrial, agricultural and other human pollution and, in particular, over-fishing, she said. But they can be aggravated by natural causes, such as disease, and the stronger storms and higher sea temperatures which are associated with global climate change.

One of the most serious consequences of the decline is that the reefs of the Caribbean may now be unable to withstand the effects of global warming. "The ability of Caribbean coral reefs to cope with future local and global environmental change may be irretrievably compromised," the team reports.

The study concerns hard corals, the tiny animals which slowly build coral reefs from the calcium carbonate that they excrete. It found that in 1977, the start of the survey period, a typical Caribbean reef was 50 per cent covered in live corals, which is regarded as healthy. By 2002 a typical reef was 10 per cent covered, which is regarded as potentially fatal.

The real importance of the study is that it has put hard figures on a process of destruction that was widely thought to be happening but the true extent of which was unknown. Coral reefs were known to represent an ecosystem under stress in the Caribbean and all around the world, but until the high-level number-crunching of the University of East Anglia study, the perception was anecdotal rather than backed by statistics.

"The feeling among scientists and tourists has long been that Caribbean corals are doing badly, since many people have seen reefs degrade over the years," Dr Cote said. "We are the first to pull all of this information together and put a hard figure on coral decline."

Assessments have suggested that 11 per cent of the historical worldwide extent of coral reefs has been lost.

- INDEPENDENT