'Rainforests of the sea' ravaged: overfishing and pollution kill 80% of coral on Caribbean reefs
18 July 2003The Independent
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 reveal today.
Human actions are almost certainly responsible for most of it. And the size of the loss, the first to be accurately quantified over a very 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, which, as The Independent reported two weeks ago, is accelerating rapidly in Brazil. 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.
"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 ones, said the team leader, Dr Isabelle Côté, 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 up 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 Côté said. "We are the first to pull all of this information together and put a hard figure on coral decline.''
Recent assessments have suggested that 11 per cent of the historical world-wide extent of coral reefs has been lost, with a further 16 per cent severely damaged, but until now there has not been an exercise in quantifying the loss in fine detail across an area as vast as the Caribbean. The final figures were a shock to all concerned.
"The end result surprised us, as well as all the people who gave us data," said Dr Côté. "The rate of decline we found exceeds by far the well-publicised rates of loss for tropical forests."
Some of the decline was prompted in the early 1980s by the mass die-off of a West Indies sea urchin that grazed on algae on the coral reefs, the report says. Its disappearance allowed the algae to flourish and out-compete the coral animals.
This phenomenon is also caused today by over-fishing, Dr Côté said. When a "layer" of algae-eating fish is taken out, the algae gains the upper hand over the coral animals.
Other causes of the coral die-off were "pollution in all its forms," she said. This included domestic, agricultural and industrial pollution, and sedimentation, which happens when steep hillsides near the coast are deforested and mud slides down into the sea and accumulates on top of reefs.
The study says some areas of degraded coral in the Caribbean appear to be recovering. "The bad news, however, is that the new coral communities seem to be different from the old ones," said Dr Côté. "At this point, we do not know how well these new assemblages will be able to face new challenges, such as rising sea levels and temperatures as a result of global warming." The study's conclusion is pessimistic. "Given current predictions of increased human activity in the Caribbean, the growing threat of climate change on coral mortality and reef framework-building, and the potential synergy between these threats, the situation for Caribbean coral reefs does not look likely to improve in either the short or the long term.''
Coral reefs are important not only for the thousands of species of fish and other animals that they host; they also play an important economic role in the communities that have grown up around them.
"Caribbean reefs host extraordinary biodiversity, provide a livelihood to millions of people and provide essential physical protection from tropical storms," said Professor Andrew Watkinson, leader of the Tyndall Centre's research into climate change and the coastal zone. "Now that the plight of Caribbean corals has been measured, there is renewed urgency for conservation action to restore this unique and important ecosystem."
ENDANGERED PARADISES
PHILIPPINES, SOUTH-EAST ASIA
More than 80 per cent of the reefs clustered around the Philippines are thought to be in jeopardy, a situation exacerbated by activities such as illegal fishing techniques. Of major concern is a remote archipelago in the Molucca Sea, where the waters of the Philippines meet Papua New Guinea. The area contains more than 1,100 species of fish and 450 types of coral.
GREAT BARRIER REEF, AUSTRALIA
Spanning an epic 1,250 miles along the East coast, this is the undisputed queen of the world's reefs. Home to more than 1,123 types of sea creatures, it was formed from the skeletons of 300 species of coral over five million years. But it has been plagued in recent decades by coral bleaching, the legacy of algae dying as a result of overfishing, pollution and coastal development.
KENYA AND TANZANIA
A rich coral reef teeming with sea creatures fringes the coastline of Kenya and Tanzania for more than 125 miles. While the reef was once made up of 50 per cent live coral, it has in recent years been reduced to a tenth of that amount. The situation has not been helped by a thriving tourist trade selling pieces of coral broken off the reef.
NORTH-WEST ATLANTIC
Cold water reefs located in deep seas off the coast of Britain have long been under threat from the nets of trawlers. Scientists have issued warnings to the European Commission against the use of trawlers that damagevast swathes of the reefs, which are up to 8,500 years old. The reefs, which were recognised only recently and have not yet been accurately mapped, are similar to those found in the tropics. But they do not need sunlight, which enables them to survive in the Atlantic at depths of 200 to 1,000 metres.
