Mascarene Islands
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The Mascarene Islands (or Mascarenhas Archipelago) is a group of islands in the Indian Ocean east of Madagascar comprising Mauritius, Réunion, Rodrigues, Cargados Carajos shoals, plus the former islands of the Saya de Malha, Nazareth and Soudan banks. The collective title is derived from the Portuguese navigator Pedro Mascarenhas, who first visited them in 1512. The islands share a common geologic origin in the volcanism of the Réunion hotspot beneath the Mascarene Plateau and form a distinct ecoregion with a unique flora and fauna.
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[edit] Nature
[edit] Geology
The Mascarene Islands are volcanic in origin; Saya de Malha (35 ma) was the first of the Mascarene islands to rise out of the Indian Ocean due to the Réunion hotspot, followed by Nazareth Bank (some 2,000 yrs later), Soudan Bank and Cargados Carajos. The youngest islands to form were Mauritius (7-10 ma), the oldest of the existing islands, created along with the undersea Rodrigues ridge. The islands of Rodrigues and Réunion were created in the last two million years. Réunion is the largest of the islands (2,500 km²), followed by Mauritius (1,900 km²) and Rodrigues (110 km²). Nazareth and Soudan were completely submerged, Cargados Carajos remaining as a coral atoll. Eventually Saya de Malha, [1] The Réunion hotspot was beginning to cool and Rodrigues came out as a tiny island. Had erosion not taken place, Cargados Carajos would have been a large volcanic island, and the Mascarenes would have been an archipelago of seven or more (counting Saya De Malha, Nazareth and Soudan) large, populated islands, rather than the three (Mauritius, Reunion, Rodrigues) that remain today.
Réunion is home to the highest peaks in the Mascarenes, the shield volcanoes Piton des Neiges (3,069 m) and Piton de la Fournaise (2,525 m). Piton de la Fournaise, on the southeastern corner of Réunion, is one of the most active volcanoes in the world, erupting last on August 13, 2004. Piton de la Petite Rivière Noire (828 m) is the highest peak on Mauritius, and the gentle hills of Rodrigues rise to only 390 m.
The Mascarene Plateau is an undersea plateau that extends approximately 2000 km, from the Seychelles to Réunion. The plateau covers an area of over 115,000 km² of shallow water, with depths ranging from 8 to 150 meters, plunging to 4000 m to the abyssal plain at its edges. The southern part of the plateau, including the Saya de Malha Bank, Nazareth Bank, Soudan Banks and Cargados Carajos Shoals (Saint Brandon) (then one large island), was formed by the Réunion hotspot. These were once volcanic islands, much like Mauritius and Réunion, which have now sunk or eroded to below sea level or, in the case of the Cargados Carajos, to low coral islands. The Saya de Malha Bank formed 35 million years ago, and the Nazareth Bank and the Cargados Carajos shoals after that. Limestone banks found on the plateau are the remnants of coral reefs, indicating that the plateau was a succession of islands. Some of the banks may have been islands as recently as 18,000 - 6,000 years ago, when sea levels were as much as 130 meters lower during the most recent ice age.
[edit] Mascarene forests
The Mascarene islands form a distinct ecoregion, known as the Mascarene forests. The islands were formerly covered in tropical moist broadleaf forest and harbored a diverse range of forest types. Near the seacoast were coastal wetlands and swamp forests, transitioning to rain forest to windward and lowland dry forest to leeward, palm savannas, montane deciduous forests, and montane heathlands on the highest peaks of Réunion.
The islands are home to many endemic plants and animals. Most of the Mascarene flora and fauna is thought to be derived originally from Madagascar and Africa. The islands have never been connected to the mainland, so the flora and fauna of the Mascarenes arrived from over the sea. Prehistoric islands of the Mascarene Plateau, now disappeared under the sea, may have served as 'stepping stones' which allowed species to island-hop from the Seychelles or Madagascar. The Mascarenes are home to one endemic family of flowering plants, Psiloxylaceae, which has only one species, Psiloxylon mauritianum. Until Europeans first settled the islands in the sixteenth century, no peoples were known to exist in the Mascarenes, so much of the island's wildlife, which would have gone extinct much earlier had any native people lived there, were still flourishing during the early days of settling.
The islands have no native mammals, except for bats. Sixteen endemic bird species survive on the islands. Many of the Mascarene birds evolved into flightless forms; the most famous of which was the Dodo, an extinct flightless pigeon of Mauritius. Mauritius, Réunion, and Rodrigues were also once each home to one or more species of giant tortoises, now extinct, which comprised the genus Cylindraspis. There are thirteen living endemic reptile species, including a number of species of day geckoes (genus Phelsuma).
Much of the native Mascarenes' flora and fauna has become endangered or extinct since the human settlement of the islands in the 17th century. Settlers cleared most of the forests for agriculture and grazing, and introduced many exotic species, including pigs, rats, cats, monkeys, and mongooses. Fourteen bird species became extinct; in addition to the Dodo, some of the other extinct species are the Rodrigues Solitaire, a flightless pigeon related to the Dodo, and the Réunion Flightless Ibis.
The Tambalacoque (Sideroxylon grandiflorum), often called the dodo tree, is also threatened with extinction, though the extent to which it depended on the dodo for reproduction, its seeds germinating only after passing through the extinct bird's digestive tract, has been challenged.
[edit] Historic colonies
The early colonial history of the islands, like that of the Caribbean, is a confusing story of takeovers between the rivalling Portuguese, Dutch, French and British colonizers, usually separate or in varying combinations, sometimes even with distant other colonies, e.g. in the East Indies.
The French succeeded in establishing a permanent hold. From 4 June 1735 to 23 March 1746, a single French Mascarene Islands chartered colony under one gouverneur général (governor general) contained Île de France (Mauritius), Île Bourbon (Réunion) and Séchelles (the Seychelles). On 14 July 1767 this becomes a French crown colony, still under one gouverneur général. From 3 February 1803 till 2 September 1810 the French colony of Indes-Orientales, under a capitaine général, includes Île de la Réunion and [nominally] the Séchelles [Seychelles]).
[edit] Islands and Banks
[edit] Mauritius
Mauritius was formed 8-10 million years ago, and is geographically one of the oldest remaining islands in the group. It was discovered in the 10th century, but the first permanent settlement was by the Dutch in 1638. It was seized by France in 1715, who remained in control until the British took over in 1810. Mauritius gained independence in 1968.
[edit] Rodrigues
Rodrigues was formed at around the same time as Mauritius. It was first discovered by the Arabs but named after Portuguese navigator Diogo Rodrigues. It was Dutch in 1601 and settled by the French in 1691. Britain took possession of Rodrigues in 1809. When Mauritius gained independence in 1968, Rodrigues was forcefully joined to it. Rodrigues remains an autonomuos region of Mauritius.
[edit] Réunion
Réunion was discovered first by the Arabs then by the Portuguese, who named it Santa Apollonia. It was then occupied by the French as part of Mauritius. It was given its current name in 1793. From 1810 to 1815 it was held by the British, before being returned to France. Réunion became an overseas department of France in 1946.
[edit] Cargados Carajos
Cargados Carajos is the remnant of one or more large volcanic islands which sank with the rising tides. Today it is administered by Mauritius.
[edit] Saya de Malha
Saya de Malha Bank is a large, submerged bank. Historically it was a group of volcanic islands, and was joined to the Great Chagos Bank until a continental drift pushed them apart.
[edit] Soudan Banks
Sounan Banks are a group of low-lying banks on the Mascarene Plateau.
[edit] Nazareth Bank
Nazareth Bank is located just north of Cargados Carajos, and historically they were a single geological feature. Today is is a large, shallow fishing bank.
[edit] Hawkins Bank
Hawkins Bank is located on the northernmost point of the Mascarene Plateau.
[edit] References
- Quammen, David, (1996) The Song of the Dodo. Touchstone, New York.
- Diamond, Jared, (1984) "Historic extinctions: A rosetta stone for understanding prehistoric extinctions". In: P. Martin and R. Klein (eds.) (1984) Quaternary Extinctions: A prehistoric revolution. University of Arizona Press, Tucson.
- WorldStatesmen- under Mauritius
[edit] External links
- Scientific research application on the nature reserve of Mare-Longue (Réunion - Mascarene Islands)
- Mascarene forests (World Wildlife Fund)
- Dispersal of the Genus Phelsuma in the Mascarenes (Phelsumania)
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