Astove Island

Astove Island is part of the Aldabra Group of the Seychelles. It is 38 km SSE of Cosmoledo Atoll, located at (coord|10|06|S|47|45|E|). It is a raised coral island of most peculiar form: a single stretch of land, more than 1 km (nearly one mile) at the widest, almost entirely encloses a shallow lagoon. This has a maximum depth of 3 metres (10 ft), and the only exit is a winding passage in the southwest, called "Gueule Bras Channel".

Astove Island measures nearly 6 km (3.7 miles) north to south and about 4 km (2.5 mi) at most east to west. The land area is 4.96 km²Verify source|date=April 2008 , and the total area including the lagoon 9.5 km²Verify source|date=April 2008 . The only settlement, on the western coast, has been abandoned since the 1980s. There is a grass airstrip on the north east point of the island, and remnants of a former coconut and sisal plantation. Today, the island is rarely visited - usually by scientists researching the lagoon's ecology - but the near-vertical drop-off from its outer reef edge is a popular location for diving cruises.

Geology and geography

Astove's unusual structure has raised questions about its formation. It was suggested that Astove is not a true raised atoll, but rather a reef flat, with the lagoon being washed out later. In any case, the lagoon indeed grows slowly, owing to rainwater, acidic from the soil's humic acids, dissolving the lagoon's carbonate rock bottom. This causes the unusual milky-white color of the lagoon's waters.Piggott (1961)]

On the large land mass towards the western tip, exposed reef rock raises to some 5 m (15 ft) ASL. Elsewhere it is largely covered by gravelly debris. Dunes of up to 18 m (60 ft) line the windswept eastern rim of the island, and the eastern part of the lagoon is especially shallow due to the inblown dune sand. Astove Island's fringing reef is just about 180 m (300 ft) wide. As noted above, beyond the reef's outer edge the seafloor drops down steeply, with a depth of 550 m (300 fathoms) a mere 300 metres (900 ft) away from the shoreline.

The climate is dominated by the southeast trade winds which are most pronounced between April and November. Temperatures are around 28 °C (83°F) in the shade during that time, and slightly higher during the northwest monsoon season. At that time, tropical cyclones with torrential rain sometimes hit the island, but overall it is very arid.



Astove Island has a very thin soil layer overlying its rocky core, which is pockmarked with caverns. Guano of nesting seabirds has accumulated in these, and the western part has been worked over and some of the guano was mined in the past. Large stretches of the reef rock were stripped bare of vegetation, but some "Pisonia grandis" and White Milkwood ("Sideroxylon inerme") persisted. The general vegetation on much of the island's western side is herbaceous plants however, mainly the leadwort "Plumbago aphylla", as well as "Stachytarpheta" species and the crowfoot grass "Dactyloctenium pilosum". Coconut Palms ("Cocos nucifera") remaining from the struggling plantation along the western shore, Sisal ("Agave sisalana"), and wild cottonplant ("Gossypium") are also found here and there. Maize ("Zea mays") was planted by the guano miners, but presumably this plant which depends on constant care has disappeared since.

The eastern dunes are overgrown with the dropseed grass "Sporobolus virginicus" near the sea, and on the higher parts "bwa matlo" (Bay Cedar, "Suriana maritima") shrubs are found. In more sheltered places, a regular scrubland of "vouloutye" ("Scaevola sericea") and Velvet Soldierbush ("Tournefortia argentea"), with some "Pisonia", occurs. Here, the main herbs are fimbries ("Fimbristylis") and the parasitic vine "Cassytha filiformis".

The flats around the lagoon show a mixture of grassland (mainly Pembagrass, "Stenotaphrum dimidiatum") and "Pemphis acidula" scrub; in places, it is difficult to penetrate to the lagoon through the mass of "Pemphis" and "bwa matlo". Small Grey Mangroves ("Avicennia marina") line much of the southern half of the lagoon rim.


Astove Island is home to four landbirds:
* Cosmoledo Abbott's Sunbird ("Cinnyris sovimanga buchenorum" or "C. abbotti buchenorum") - only occurs here and on nearby Cosmoledo
* Madagascar Cisticola ("Cisticola cherina")
* Pied Crow ("Corvus albus")
* Common Madagascar White-eye ("Zosterops maderaspatanus maderaspatanus")

There are few seabirds, probably due to the presence of rats and feral pigs, left behind when the settlement was abandoned. Unlike the other two atolls of the group, (Aldabra and Cosmoledo), there are no predator-free islets except for a few small sandbanks close to the lagoon entrance. At the lagoon, Caspian Terns ("Hydroprogne caspia") will often be seen but it is not known whether or not they ever breed on the sandbanks. Indopacific Sooty Terns ("Onychoprion fuscatus nubilosus") and Western Black-naped Terns ("Sterna sumatrana mathewsi") have also been reported. Green Turtles ("Chelonia mydas") remain very common here despite years of exploitation and remarkably high numbers will be seen on dives or from tender trips to the lagoon entrance close to high tide.



* (1961): Notes on some of the Seychelles Islands, Indian Ocean. "Atoll Research Bulletin" 83: 1-10. [ PDF fulltext]

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Astove Island — Satellitenbild der Astove Insel Astove (engl. Astove Island) ist eine kleine Insel im Indischen Ozean, nördlich von Madagaskar gelegen, die zur Inselrepublik der Seychellen gehört. Sie liegt etwa 38 Kilometer südlich des Cosmoledo Atolls und… …   Deutsch Wikipedia

  • Astove — Géographie Pays   …   Wikipédia en Français

  • Astove-Insel — Vorlage:Infobox Insel/Wartung/Höhe fehlt Astove NASA Bild der Astove Insel Gewässer Indischer Ozean …   Deutsch Wikipedia

  • Astove — Satellitenbild der Astove Insel Astove (engl. Astove Island) ist eine kleine Insel im Indischen Ozean, nördlich von Madagaskar gelegen, die zur Inselrepublik der Seychellen gehört. Sie liegt etwa 38 Kilometer südlich des Cosmoledo Atolls und… …   Deutsch Wikipedia

  • Île Astove — Astove Island (en) Image satellite de l île Astove. Géographie Pays …   Wikipédia en Français

  • Aldabra Group — The Aldabra Group are part of the Outer Islands of the Seychelles, lying in the southwest of the island nation, 1000 kilometres from the capital, Victoria, on Mahé Island.The total land area of the Aldabra Group is 175.91 km².Islands in the… …   Wikipedia

  • Астов — фр. Île Astove …   Википедия

  • Cosmoledo — Seychelles Overview Map Cosmoledo Atoll from the air …   Wikipedia

  • List of islands of Africa — This is a list of islands of Africa.Cape Verde*Boa Vista *Branco *Brava *Fogo *Maio *Raso *Sal *Santa Luzia *Santo Antão *São Nicolau *São Tiago *São VicenteDjibouti*Maskali Island *Moucha Islands *Sept Freres, DjiboutiEquatorial Guinea*Annobón… …   Wikipedia

  • Geography of Seychelles — Map of Seychelles The Seychelles is a small island nation located in the Indian Ocean northeast of Madagascar and about 1,600 km (994 mi) east of Kenya. Seychelles lies between approximately 4ºS and 10ºS and 46ºE and 54ºE. The nation is …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”