Aldabra is a group of islands that has a unique biogeography. The island is situated in the Indian Ocean and are part of the Outer Islands of the Seychelles. Aldabra is one of the world’s largest coral atolls. It lies between Africa and Madagascar and is volcanic in origin. It developed around 50, 000 years ago which makes the island geologically extremely young. The island has not really developed much soil due to its relatively young age. It consists of raised coral with a maximum height above sea level of 8 metres. There is some soil largely from guano, coral and other marine detritus.
This island, like many other remote islands, has allowed an ecosystem to develop in relative isolation. The unique flora and fauna includes a giant tortoise (Geochelone gigantea). These tortoises may exceed 1 metre in length and are similar to those that evolved independently on the Galapagos Islands in the Pacific Ocean. The tortoise is endemic to the islands of Aldabra and the Seychelles. A population of the Aldabra giant tortoise have also been introduced to other islands such as Mauritius, Reunion, and granitic islands of Seychelles such as Curieuse and Fregate. The species is considered to be vulnerable and is on the International Union for Conservation of Nature (IUCN) Red List. According to this arkive.org link there is only one wild tortoise left with others being in a captive breeding programme. The tortoise has been exploited by humans in the past and the population negatively impacted by the introduction of non-native species. The terrestrial flora includes some 178 species of indigenous flowering plants, of which about 20% are thought to be endemic (i.e. only found in that place).
Described by Julian Huxley, the evolutionary biologist, as “one of nature’s treasures” the island is now a World Heritage site. It achieved this protection in 1982. The island is highly protected and is managed by the Seychelles Islands Foundation (SIF). It is managed under a Strict Nature Reserve of the IUCN Management Category and designated as a Natural World Heritage Site. This foundation has enabled the ecosystem to be conserved and managed to protect the species that only exist here. The island is an example of where conservation measures work to maintain the ecosystem: the Strict Nature Reserve status maintains a biogeography that is only found here. The reserve allows Aldabra to be a sustainability success story.
References – The following links have more information on Aldabra: