| Aldabra Atoll* | |
|---|---|
| UNESCO World Heritage Site | |
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| State Party |  Seychelles |
| Type | Natural |
| Criteria | vii, ix, x |
| Reference | 185 |
| Region** | Africa |
| Inscription history | |
| Inscription | 1982 (6th Session) |
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* Name as inscribed on World Heritage List. ** Region as classified by UNESCO. |
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Aldabra, the world's largest coral atoll, is in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. Uninhabited and extremely isolated Aldabra is virtually untouched by humans, has distinctive island fauna, including the Aldabra Giant Tortoise and is designated a World Heritage Site.
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Aldabra was visited by Portuguese navigators in 1511. The islands were already known to the Arabs, from whom they get their name. In the middle of the 18th century, they became dependencies of the French colony of Réunion, from where expeditions were made for the capture of the giant tortoises. In 1810 with Mauritius, Réunion, the Seychelles and other islands, Aldabra passed into the possession of Great Britain. Réunion was returned to France, and Mauritius gained possession of Aldabra as well as the rest of the Seychelles. The previous inhabitants were emigrants from the Seychelles. Sailors landed on the atoll in the 19th century and attempted to raid the island for tortoises as food; in 1842, two ships were reported to have taken 1200 of them. By 1900, the tortoises were nearly extinct, and a crew would often have to hunt for three days to find one.[1]
The Aldabra Atoll, along with Des Roches and Farquhar, was part of the British Indian Ocean Territory from 1965 until Seychelles independence in 1976. In the 1960s, the British considered allowing the United States to use the island as home for a military air base. After an international protest by ecologists, however, the military plans were abandoned and the wildlife habitat instead received full protection.[2] Aldabra was designated a World Heritage Site on November 19, 1982, and is administered from Mahé by the Seychelles Island Foundation.[3]
The abandoned settlement Picard on the southwestern tip of West Island is now home to the Research Officer, Island Manager and their rangers and staff. There is no other permanent population.
The island is more than 700 miles from Mahé, the principal island of the Seychelles and is closer to the coast of Africa and is 265 miles northwest of Madagascar and a similar distance northeast from the Comoro Islands. The atoll is located at 9°24′S 46°22′E / 9.4°S 46.367°E and belongs to the Aldabra Group, one of the island groups of the Outer Islands of the Seychelles, which includes the island of Assumption and the atolls of Astove and Cosmoledo. [4]
The atoll is the second largest in the world after Kiritimati. It is 34 km long, 14.5 km wide, up to 8 meters above sea level, and has a land area of 155.4 km². The lagoon measures 224 km² in area, of which roughly two thirds fall dry during low tide. The atoll consists of a ring of four larger islands: counterclockwise, they are South Island (Grand Terre, 116.1 km²), Malabar or Middle Island (26.8 km), Polymnieli or Polymnie Island (4.75 km²) and Picard or West Island (9.4 km²).
. Additionally, there are some forty smaller islands and rocks, all inside the lagoon, except a few very small islets at the West Channels between South and Polymnie Islands, the largest of those being Îlot Magnan. The largest islands inside the lagoon are Île Michel (Coconut Island), in the east (0.34 km² or 0.16 sq.mi.) and Île Esprit (Euphrates Island), in the west (0.41 km² 0.13 sq.mi.).
The islands consist of limestone uplands, sand dunes and beaches based on the remains of a coral reef.
Aldabra has a number of endemic plant species. The higher areas are covered in species of pemphis, thick coastal shrubs, while the lower areas which are home to the giant tortoises, are a mixture of trees, shrubs, herbs and grasses.
The atoll is home to the world's largest population of giant tortoises, the Aldabra Giant Tortoise (Dipsochelys dussumieri), numbering some 150,000 individuals.[5] They are also known for their Coconut crab (Birgus latro), the world's largest land crab, and hammerhead sharks, manta rays, barracuda and as a breeding ground for green turtles and hawksbill turtles. Birds of Aldabra include the Aldabra rail, the last surviving flightless bird of the Indian Ocean region and the endangered Malagasy Sacred Ibis as well as large numbers of nesting seabirds.
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ALDABRA, the collective name of a group of islands in the Indian Ocean, forming part of the British colony of Seychelles. They lie in 9° 30' S., 46° E., are 265 m. N.W. of the northern point of Madagascar and 690 m. S.W. of Mahe, the principal island of the Seychelles archipelago. The Comoro Islands lie 220 m. S. by W. of Aldabra. The Aldabra Islands constitute an atoll consisting of an oval ring of land, some 40 m. in circumference and about 12 m. broad, enclosing a shallow lagoon. Channels divide the ring into four islands. Grande Terre or South Island forms three-fifths of the circumference. The other islands are West Island or Ile Picard, Polymnie and Middle Island. There are in addition several islets in the lagoon, the most important being Ile Michel. The total land area is estimated at about 60 sq. m., the lagoon, 16 m. long and 4 m. wide, covering a somewhat larger area. Pop. (1906) 127. The islands rise from 20 to 80 ft. above the sea, and consist of rugged coral rock and limestone, there being very little soil. The sea-face is generally overhanging cliff, but in a few places are sandy beaches and low sandhills. Dense scrub covers most of the land, but the inner (lagoon) shore is everywhere bounded by mangrove swamps.
The flora and fauna of the islands present features of unusual interest. They are chiefly noted as the habitat of the gigantic land tortoise (Testudo elephantina), now carefully preserved, and of several rare and peculiar birds, including a rail (Dryolimnas aldabranus), an ibis (Ibis abbottii) and a dove (Alectroenas sganzini). Crustacea are abundant. They include oysters, crabs of great size, and a small mussel, found in enormous numbers. The flora includes mangroves, Rubiaceae, Sapotaceae and other forms requiring more than pure coralline material for their growth. Writing of the fauna and flora generally, Mr R. Dupont, curator of the Botanic station at Mahe, who visited Aldabra in 1906, says: "The specimens represented, besides being partly peculiar, mostly belong to the Mascarenes, Madagascar and Comoros species. Many species are also common to East Africa and to India.. .. The predominant species are Madagascar plants and birds, which are carried by the currents and the winds.. .. There are comparatively few (10) species of plants which are endemic as far as the flora has been investigated, and it is probable that most of them are also existing in the Comoros, where the flora is not well known.. .. Endemic inferior animals and mammals are practically non-existent, except two bats and one scorpion, which are allied to Madagascar species or introduced. The reptiles (tortoises) are also nearly allied to the Mascarenes and Madagascar species which once existed. With regard to birds and land shells the relation is much closer to the Comoros species, and the latter, of which I have collected seven species besides Rachis aldabrae, may serve to point out more than the birds the land connexion of Aldabra with the neighbouring countries." Aldabra, however, although situated in that region of the Indian Ocean which forms part of the site of the IndoMadagascar continent of the Secondary period, is not a peak of the submerged land. It has been built up from the sunken remains of the old continent by a deposit, in the opinion of Professor A. Voeltzkow, of foraminiferal remains (mostly coccoliths and rhabdoliths). In any case, however Aldabra was formed, there can be no suggestion of its ever having been joined to any other land (Stanley Gardiner). Dupont states that at Aldabra the coral foundation is totally above water. The coral limestone of the atoll has a peculiar vitrified appearance and gives out a ringing sound when struck or simply walked on. The coral is generally reddish, but the colouring ranges from light yellow to chocolate-brown.
Aldabra was visited by Portuguese navigators in 1511. The islands were already known to the Arabs, from whom they get their name. They became in the middle of the 18th century dependencies of the French establishments at Bourbon (Reunion), whence expeditions were made for the capture of the giant tortoises. In 18ro with Mauritius, Bourbon, the Seychelles and other islands, Aldabra passed into the possession of Great Britain. The inhabitants are emigrants from the Seychelles. Goats are bred and coco-nuts cultivated, but fishing is the chief industry. With other outlying islands Aldabra is held under lease from the Seychelles government, the lessees having exclusive trading privileges.
See R. Dupont, Report on a Visit of Investigation to ... the Aldabra Group of the Seychelles Islands (Seychelles, 1907); Dr Abbott in Proceedings, United States National Museum (Washington, 1894); A. Voeltzkow in Abh. der Senckenbergischen Naturforschenden Ges. vol. xxvi. part iv. (1901); J. S. Gardiner, "The Indian Ocean," Geo. Journ. Oct. 1906.
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Categories: ALD-ALI | Seas and Polar regions
   | Photos of Aldabran wildlife - Aldabra - Indian Ocean - Travel Photos by Galen R Frysinger, Sheboygan, Wisconsin |
| | Aldabra Island xeric scrub (World Wildlife Fund) - Terrestrial Ecoregions -- Aldabra Island xeric scrub (AT1301) |
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