Questions… Enigmas… Mysteries… (5)

Atolls: a geological mystery

That might remain unresolved forever

Evelina Rioukhina, UNECE

After hours and hours of flight over the deep blue ocean the eye is suddenly captured by an unrealistic vision of small, almost white, round spots against the dark-blue background. The plane loses its altitude and the small spots turn into weirdly formed circles of different sizes, some tiny, others bigger ones, some of perfect circular form, others oval. There are very big, almost huge borders around and many smaller or tiny spots or circles inside. The colours are breathtaking, from almost white to near black, passing through all shades of blue, turquoise and green. The whole image looks like a huge surrealistic painting where the artist painting in deepest blue suddenly took a huge brush with white colour and poured it into the blue to turn the thousands of small and large drops into a surrealistic vision. 

The plane still descends, and some tiny pieces of sand of different shape – also circular, sometimes triangular, turn into tiny islands, some covered with vegetation, other just of white sand. Another wide turn – and this time the eye is attracted by huge golden cupola on one of the larger islands, lower still – one can see the trees, houses, streets of this island- town – this is the capital, the unique and only capital-island, the smallest capital in the world. The plane goes down and down, 100 metres, 80, 60, 40…0 (!!!) meters…Nothing but water around, you literally land on it. Only at the last moment does the plane touch hard ground, but you still see the water on both sides, and thinking that you are in the middle of the nowhere, you hear the voice “Ladies and Gentlemen, our aircraft has just landed at the international airport”. Yes, you have just landed at the most unique and perhaps the most difficult airport in the world (an airport-island, whose runway begins and ends in the water) and you have just arrived at the most beautiful, paradise place in the world – the Maldives.

The Maldives – A nation of islands scattered across the equator in the midst of the Indian Ocean – the gem-like islands of the Maldives depict the rare vision of a tropical paradise. Palm-fringed islands with sparkling white beaches, turquoise lagoons, clear warm waters and coral reefs teeming with abundant marine flora and fauna that continue to fascinate visitors, as they have fascinated others for thousands of years in the past. Marco Polo referred to the Maldives as the « Flower of the Indies » and Ibn Batuta called her in his chronicles one of the wonders of the world.

Truly a natural wonder, the Maldivian atolls are a classic discovery in their own right. The Republic of Maldives, with its 26 atolls and their smaller compounds – is formed of 1,196 islands (estimates of the number of islands differ, depending on the definition of an island as “some form of vegetation on them, whether grass of bushes or trees”; if sand bars and coral outcrops were included the figure would be closer to 2,000), among which 200 islands are inhabited. It covers an area of 90,000 sq.km and lies between Latitude 7 degree 6’30’’ N to 0 degree 41’30’’ S, and Longitude 72 degree 32’30’E to 73 degree 45’15’’ E. The islands constitute the main part of the Maldives archipelago, which stretches for nearly 900 kilometres in the Indian Ocean, and consists of a twin series of atolls standing on a wide submerged platform located at a depth of 270-500 metres, bounded by waters which reach a depth of 2,500 metres on the east side and approximatively 4,000 metres on the west side. An atoll (the name is derived from the Maldivian athulu, which indicates both natural atoll and administrative unit) is defined as a coral formation surrounding a circular central lagoon whose size can range from a few to a large number of kilometres.

Because of their characteristics, atolls, more than any other kind of coral reef, have attracted the attention of researchers, who have endeavoured to explain their origin. To this day, however, despite years of research the origin of these unique atolls remains a mystery. In 1842, after studying other similar atolls in the Pacific and Atlantic oceans, Charles Darwin suggested that they were created when volcanic land rose from the sea and a coral reef grew around its edge. The volcano gradually sank back into the sea leaving the coral reefs to encircle a shallow water-filled lagoon. Islands then developed when currents and tides swept coral and other organic debris into sand bars, which eventually were colonised by plants and trees. When Darwin, continued his studies he had to admit that there was something special about the Maldives islands. Nevertheless he added that his theory of coral island formation was applicable to the Maldives in a general sense, and most scientists accept his theory. A different view has been provided by Hans Hass. According to him, layers of coral reefs might have built up on top of the submerged mountains until they rose to the surface. The hardest and highest corals remained while the weaker corals in the centre of the coral platforms broke down. The remaining corals at the outer edges formed rings that were to form the outer rims of atolls. Islands were formed as debris and sand accumulated on to the remaining reefs. There are other hypotheses and at present considerable research is conducted by NASA with the use of GIS – the Geographic Information System. (For further details on this research please read studies on Maldives by the NASA Earth Observatory at http://earthobservatory.nasa.gov).

One of the unusual features of the Maldives is the composition of its atolls, which are formed by a number of small atolls called faru or farus, separated by channels or passes (kandu) of various widths, which enable water, fish, nutrients and waste matter to be exchanged between the open sea and the lagoons.

In addition, the action of the monsoons seems to have a major effect on the shape of the farus and the existence of a double chain of islands. Monsoons are periodic winds which blow from south-west in summer and from north-west in winter, affecting the coasts of the Maldives alternately and reversing the dominant currents. The general result of the seasonal alternation of the currents and the prevalent wave direction is a symmetrical development of atolls. The changing and alternating ocean conditions cause the coral to grow in all directions, not in one prevalent direction as is the case with other reefs on which constant winds blow in only one direction.

More than ten years ago I met a family the members of which have for years been passionate students of the Maldivian ecosystem with its coral bio and animal diversify and who participate every year in different exploring expeditions. Thanks to them, at their invitation and on our own initiative over a period of 10 years I have been fortunate enough to make detailed explorations, including overflights of all the atolls, to visit and study in detail six atolls, and to explore 40 islands and numerous diving sites for their coral and animal life and can confirm that nothing can compare with the breathtaking sights both from the air and from the deep of the ocean. If air sights are still overwhelming the natural disaster of 1998 completely changed the coral scenery, when a sudden rise of 2-3 degrees in temperature turned the wonderful colourful underwater gardens into burnt-out, ashen scenes of desolation, killing from 70 to 90 per cent of the corals depending on the atoll (the article on this event was published in UNS 590, November 2000).

Vast measures are being taken now to restore the corals, several costly projects have been urgently launched to save the reefs by using cone- shaped steel frames as nurseries for the corals, passing a small electric current through the metal to form a layer of limestone, and very recent observation, in 2004, of coral spawning under the full moon have proven that, although it might take time, this is road to regeneration. (See “ECO News”, 4 June 2004).

As for the protection of the individual islands, the biggest project ever in the Maldives is under way. It is to build a breakwater in Male North Atoll, on Male’s southern reef, aimed to protect the capital (the project is financed by Japan, for details see most recent documentation of the Global Coral Reef Alliance).

As for the still unresolved puzzle of the atolls, this is to wish all success to the extensive research under way, using the latest technology including GIS. Understanding the geography of the atolls, is now more than ever a matter of primary importance, knowing how they were formed and how the coral reefs grew could help the

Maldives people to shield themselves from the rising level of the ocean. If, as some scientists predict, the sea level will continue to rise as a result of global warming then the Maldives, with their ancient and unique culture, may be swept away within fifty years. There is a group of scientists who think that this may happen sooner, even in the nearest future. And even if, hopefully, it might be possible thanks to the above measures to keep at least the most populated island(s) afloat, the rest of the atolls might disappear under the water, taking their secrets with them forever.