|AROUND THE EDGES OF MANY CARIBBEAN ISLANDS, most of what was once a thick band of elkhorn coral has died from white-band disease. The striking skeletons have disintegrated into piles of rubble. Deeper, the coral reefs are now expanses of seaweed, with only the occasional coral still visible. |
I had sought the necessary permission to publish in a scientific journal a report on the devastation in one particular country, but was told that such a move would, apparently, bring unwelcome publicity.
It could stop divers coming here, said a senior official from the small island state.
But when they come, and find that it isnt like the old photos you put out, wont that annoy them and stop them coming again I asked.
Doesnt matter, the official replied. There are enough divers out there that if they all come only once, thats all we need.
And I never did get permission to publish the results, even in a journal read only by scientists who could have helped the situation. So I cannot say which country that was, nor who funded the research but, as with almost all research, it came from the taxes of somebody, somewhere!
This was not atypical.
Another country, another year. The same disease had eliminated the elkhorn coral which should form a natural breakwater for Caribbean shores. Its powerful branches would once angle into breaking waves and absorb their energy, preventing erosion of beaches. Here too, however, the result was piles of shifting rubble, and a massive loss of beach sand.
One beach had lost all its sand, leaving only the underlying, jagged and razor-sharp rock (called karst limestone), not something which tourists in nearby hotels had paid $300 a day to stretch out on under a beach umbrella.
The coast road along the way was also being undercut, and behind the road were oil storage tanks. I saw the chief minister as part of my duties, and explained the problem.
How long before the erosion undercuts the oil tanks asked the minister.
Six to 10 years. Difficult to be certain, I replied.
Oh, thats all right then. Im only in office for five more years. Someone elses problem.
Again, I am not at liberty to say where this occurred. I do know, however, that an article in another diving magazine recently was accompanied by very old photos, because the site in question hasnt looked that good for at least 10 years!
I have always been puzzled by the limited vision of some of our senior officials. After all, these problems wont go away by themselves and eventually will (indeed, already do) cause marked economic problems for the countries concerned.
Last year, diving with a research student off the Bahamas Field Station in San Salvador, coral cover was negligible. The coral reef, which once had two-thirds cover of corals, now had only about 5 per cent. Good for seaweed specialists, I suppose, joked a visiting American professor, somewhat sadly.
What has caused all this, and where is it leading What is happening to the reefs, and what about the coral islands which rest on them What about the tens of millions of people who depend on them
The two main phases of reef destruction can be conveniently divided between pre-1998 and post-1998.
Before that year, numerous forms of reef mining, pollution (especially from sewage and agricultural run-off) and destructive forms of fishing were mainly to blame. This is when so much elkhorn in the Caribbean died.
Then, in the El NiÃ¢â‚¬â€œo year of 1998, we recognised a new factor: seawater warming was having a massive effect. All the earlier problems still happen, but are now compounded by an event which has had the most massively destructive impact on reefs for several hundred years.
Many scientific articles have been written about these issues, yet two big but related gaps remain.
One is the political one of lack of interest at high government levels, caused sometimes simply by fear of an out-of-control situation. The other is the gap which has always existed between the huge amount of information in science journals and that available to the broader audience.
There are now significant moves to suggest that our concerns about reefs are not terribly important, or that the damage isnt happening anyway. The suggestion that scientists never agree on anything is often used as an excuse for authorities not to take any action. In fact, scientists dont disagree on these matters nearly as much as some would have you believe! Here are a few facts, and you can make up your own mind:
the Caribbean region
This is where they make the advertisements for rum, exotic holidays, diver training agencies and even British Airways. Coral reefs here suffered greatly from diseases during the 1980s and 1990s, for reasons that were not always clear.
If you can, visit the website coastal.er.usgs.gov/african_dust. It shows a satellite image of a dust-cloud whipped up over north Africa (the protective vegetation cover of which is now in a very sad state) and blown across to the Caribbean.
This cloud contains trillions of micro-organism spores, which new research suggests might have a lot to do with the wipe-out of corals. Red tides are also blamed on this.
Another contributing factor in the Caribbean is greatly increased nutrients from poor agricultural practices in both North and South America. The run-off now causes a stagnant layer on the bottom of the Gulf of Mexico which grows bigger every year, and encourages seaweed growth on reefs.
Overfishing has also removed herbivores which would have helped to keep seaweed down. So over about 20 years most reefs have shown a marked decline, without recovery.
Leading scientists have referred to this as a collapse in the reef system, with corals on a steep downward trajectory to approximately zero.
This might surprise many divers. If you have been on a holiday in the Caribbean, but usually dive in the English Channel, you will have felt as if you were seeing for miles under water. But scientists like to compare the Caribbean as it is now with what it was like before - and even with what it could be like.
In many of the Windward and Leeward islands, Greater Antilles and, beyond the Caribbean, the Bahamas, so many other once-coral reefs are now seaweed-covered limestone plinths. Most of this has been caused by a range of environmental effects, but it was added to considerably in some areas by warming in 1998.
the Indian Ocean region
Seawater warming in this region in1998 caused probably the largest coral wipe-out we have witnessed since the last ice age. First hit were the popular diving areas of the Maldives. The great majority of corals died to 40m deep. Where there was a cover of typically 80 per cent of coral, soft coral and seafans, 5 per cent was left and, in many places, none at all.
We know that the same thing happened in much of the Seychelles and Chagos atolls, but the Maldives is where so many people go to dive. There the dead corals are eroding and turning to rubble. New corals are developing, but it will take many years to get the reefs back to where they were, and there are two big ifs associated with that.
The first is that the crumbling dead corals swash about in the waves - not a good place for a baby coral to survive. Second is that the overall temperature trend is still rising, so we are fairly certain that further hits will set them back again. The past 20 years has, after all, seen the 10 warmest years ever recorded.
The northern Red Sea escaped. Quite why, we dont know - perhaps it is simply too far north. The diving remains good.
The southern Red Sea was badly hit, but there is little recreational diving there, and the Arabian Gulf was nearly wiped out completely, though we still have no idea about Iranian reefs - or even where they are!
Sri Lankan reefs were moderately badly affected, as were those along the East African coast, though in neither case as badly as the devastation visited on the islands. Over most of the large expanse of ocean, and in huge Madagascar, coral mortality was patchy, with reports of sometimes only 25 per cent, and in other sites up to total mortality.
Those of us who do research in such areas use satellite maps of ocean temperature and its hot spots. These are updated frequently, and you can find them at orbit-net.nesdis.noaa.gov/ orad/coral_bleaching_index.html . This site includes details of global sea surface temperatures, including animations of its rise wherever it occurs. It is updated regularly, so you can track events at your next diving holiday location!
Mauritius was lucky, and worth mentioning. It was not only temperature which killed the Indian Ocean corals, but increased ultra-violet penetration. When the Indian monsoon failed that year, the water stayed glassy calm, so more light penetrated.
Over Mauritius, heavy cyclonic cloud stopped the UV light - it was as lucky as that.
This huge region had a mixed response to the warming. Corals started dying in January 1998 in western Indonesia, then spread throughout. Parts of most archipelagos, and western Australia, seemed to escape, while other parts not far away experienced coral bleaching of 25-100 per cent. In some places a lot of the bleached coral recovered later, while in other sites it mostly died and is now disintegrating.
Some corals that died were 9m across and more than 500 years old, which helps to answer that common question loved by ministers: how do we know that this isnt all a natural cycle, and nothing to do with our greenhouse gases
If it is a natural cycle, it lasts for more than half a millennium. Research by geologists in the Caribbean suggest that it has not happened for several thousand years. But climate and its cycles is a big subject.
the Great Barrier Reef
This was more affected near mainland Australia than it was on its outer edges. Japan, Papua New Guinea and most other areas suffered in similar, mixed ways, with more than 75 per cent mortality of corals over huge areas in many. This compounded the problems of over-fishing and destructive fishing which have long afflicted parts of the South-east Asian region.
the Pacific Ocean
Most of the central Pacific escaped this massive thermal shock. Indeed, across most of it, temperatures fell to a little colder than normal. The climate oscillation known as El NiÃ¢â‚¬â€œo is a complicated system, and part of its cycle involves the less well-known La NiÃ¢â‚¬â€œa, which brings cooling.
A drop of as much as 10Ã‚C can happen in a few days, and this too can cause mortality among corals.
So most Pacific island groups were affected less than elsewhere, but as we move towards the Pacific coast of the Americas, bleaching and subsequent mortality rose again.
The extreme eastern reefs had been hit before, by a similar, though lesser, event in 1982-3.
So does all this matter and, if it does, to whom What is the cost, and how long will the reefs take to recover
Several hundred million people depend on the reefs for some, if not all, of their protein. Billions of pounds (of your money too, given the nature of world finance) are tied up in threatened infrastructure which is now increasingly at risk.
Everybody has heard the word biodiversity, and reefs contain more of that than any other marine habitat.
Maintaining biodiversity is not just some esoteric idea beloved by ecologists. It keeps the natural world from collapsing, which means keeping it intact for us, and keeping it yielding, among other things, food and pharmaceuticals.
It also matters because reefs can be used as a barometer for whats happening. This reef death has been described as a wake-up call.
The main misunderstanding is that all this is a matter of saving the environment, of environmentalists versus the rest. It isnt the environment that needs saving. It will survive just fine - it might be warmer, perhaps drier, but it is not a living, sentient thing that needs protection.
What does need protecting are the habitats and species which depend on the environment staying within fairly fine tolerances. And that includes us.
Reefs continue to be degraded, and four years after the warming which added so much to that degradation, we still dont understand the full consequences.
I am surprised that so few audiences are aware of the threats to reefs, or that a third of the worlds reefs have been destroyed, or come under severe threat in the past few years. But authorities dont always take a long-term view, and the media dont always grasp the importance of the subject.
I predict dire changes in our coral reefs, but you can make up your own mind. If you wonder what you can do to help, here are two main things:
First, shout about it. Ask questions of the aid agencies and governments. This, I believe, does more good than you might at first think.
Second, whenever you go to a reef on a diving holiday, offer your help to one of the worldwide reef monitoring organisations, which in Britain could well be the Marine Conservation Society. You can help to build up the body of knowledge without which nothing useful can be done.
And if, on your holiday, you find that the reefs are damaged, make sure that the tour operators and authorities know that you know!
|An expanse of dead table corals. These slopes once had 90 per cent living-coral cover - now it is only 5 per cent. This is a sheltered site, so the corals remain standing (just) after three years. |
|The now-rare live coral of the table group |
|Table coral which has died and is now covered with red and green seaweeds. |
|Most Indian Ocean boulder corals died in 1998. Note how the surface features are becoming eroded away. |
|This was how the live boulder coral would have looked before |
|The spring coral Lobophylla, with the red live polyps visible among the dead ones. |
|Surviving parts of corals are usually shaded - here the top part exposed to ultra-violet light is dead, but the base has survived |
FIND OUT MORE FROM:
- International Coral Reef Initiative (www.environnement.gouv.fr/icri/
- Marine Conservation Society (01989 566017, www.mcsuk.org/home.html)
- Meteorological Office (www.met-office.gov.uk/research/
- NOAA (National Oceanic and Atmospheric Administration) Coral Health & Monitoring Programme (coral.aoml.noaa.gov)
- Reefbase (www.reefbase.org)
- Seas at the Millennium, an Environmental Evaluation, ed. Charles Sheppard. Also Marine Pollution Bulletin 40, pp569-597 (Elsevier Science, Netherlands, 0031 20 4853757)
- World Atlas of Coral Reefs, United Nations Environmental Programme-World Conservation Monitoring Centre (01223 277314)