Green Blog

 

Searching for 'Nemo' - or the demise of the coral reefs in the Pacific islands.

 

Since Disney released the so famous Nemo movie, the little Clown Fish has become somewhat of an icon for the underwater world of the coral reefs. Unfortunately though, it has become more and more difficult to find one in the wild. The 'Sea Anemones' - a species of soft coral that he relies on for his habitat, has become a rare find on a visit to the coral reefs of the Pacific islands. Why? The answer is sadly connected to the previous topic of my Green Blog: Global Warming.

 

We just returned from jet another visit to the Pacific Islands - Western Samoa. And the trend that I have been able to observe first hand over the last decade is one of sometimes gradual and sometimes staggering decline of the coral reefs that I have visited and re-visited over the years. And yes, we did still find one small patch of Sea Anemones there and with it one lonely colony of Clown Fish.

 

My observations began in 1995 and 1996 as I sailed from the US to New Zealand, stopping at many islands from the Marquesas in French Polynesia to the Cook Islands, Tonga, Fiji and Vanuatu. In these years the reefs appeared generally in good shape with a great variety of corals and a rich sea life thriving around them.

 

But already in the year 2000, when I revisited the Cook Islands - especially Aitutaki - the reefs seemed to have suddenly changed. Large parts of the wonder world of the reef were transformed into an assembly of dead looking structures, sometimes covered in a carpet of green-brown slimy algae. A local dive master explained that in 1998 - one of the warmest years on record - a current of warm ocean water came past the island and bleached the coral reef almost overnight. Thereafter green slimy algae took hold and replaced the symbiotic algae that grow on a healthy coral colony and provide it with its nutrients.

 

Corals live in a symbiosis with a covering of symbiotic algae which they need for their survival just as we need our gut flora. Research has shown that these symbiotic algae are particularly sensitive to the water temperature and salinity and if the temperature rises even slightly above a critical threshold and remains there for about a couple of weeks or the salinity of the water changes slightly, they are expelled by their coral host and die. The exposed coral then begins to look white or 'bleached'. Unless the exposed coral is able to recover its symbiotic algae quickly, it too will die. While the damage done by brief excursions of temperature can often be repaired, this is not so if the temperature is maintained high long enough and the coral organism dies or the new sort of green-brown slime can take hold. At that point recovery of the coral colony is unlikely.

 

We later in 2003 visited some of the most stunning reefs that we had found in 1996 in the Yasawa islands in Fiji, only to find the same. The reefs had practically been transformed into a dead looking mass with only a few live corals here and there and a shadow of its original richness in fish life.

 

In 2004 we found that reefs in Samoa, situated in generally warmer conditions than Fiji and the other islands I mentioned, still showed reasonably healthy reefs. Now in 2006 we returned to some of the same spots and unfortunately also there the decay was now noticeable with perhaps 50% of the corals dead in one area that we especially liked two years before.

 

And it seems that soft corals have been hit hardest of them all, while some other species like Fire Corals in the shallows of the lagoons seem to have survived, perhaps as they and their symbiotic algae are subjected and used to a large daily change in temperature in the rhythm of the tides and the sun? The coral species in the waters between 2 and 10 meters seem to suffer the most. This is the area where the sea temperature undergoes only smaller daily changes but is most affected by global warming - an overall sustained change in temperatures.

 

Besides warming of the oceans, over-fishing, pollution and coral predators such as the 'Crown of Thorn' starfish are part of the problem. But most marine scientists believe that warming is the key factor in the demise of the coral reefs.

 

According to a recent BBC report 40% of the world's coral reefs have been seriously damaged since 1998. The report says: 'The situation is particularly serious in the Indian Ocean, where certain areas could be totally devoid of living coral in 20 years; and the Caribbean, where the amount of reef covered by live coral has shrunk by 80% in the last three decades.' My personal observations in the South Pacific seem to conform to the findings of this report and many others.

 

The corals are attacked by the double hit from ocean warming and the rising ocean acidity due to the rise in CO2 content in the atmosphere. CO2 is causing the oceans acidity to rise as the water dissolves more CO2 from the atmosphere and Carbonic Acid is generated in the process. Coral growth - very slow anyway - slows markedly even with a slight increase in ocean acidity. Coral reefs are likely the area of the world with the highest density in species and are playing a vital role in the oceans eco system and food chain. Their loss will have a ripple effect through many other connected eco systems and will affect much more than the local economies and eco systems of the coastal regions in question.

 

Finding Nemo in the wild might thus become an elusive task by the end of the century and our grand children will perhaps know him only through his Disney legacy.

 

By the way, the northern hemisphere summer seems to develop once more into a serious heat wave as especially the South-Eastern US and Western Europe are sweltering at temperatures reaching over 40 degrees. South England is forecast to reach a new all time summer record of perhaps 39 degrees centigrade in the next week, eclipsing the previous records of 2003, while power generators are having a hard time coping with the high demand and with their own plant cooling problems. Much of the electric grids are operating close to their breaking point.

 

For people interested in perhaps the definitive article on the state of global warming, this is the link: http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf

 

Thomas Everth