Saya de Malha | |
|---|---|
Submerged bank   Saya de Malha Bank (Indian Ocean) | |
 Map of Saya de Malha | |
| Coordinates: 10°30′00″S61°21′36″E / 10.500°S 61.360°E | |
| Country | Mauritius |
| Area | |
| • Total | 40,808 km2 (15,756 sq mi) |
The Saya de Malha Bank (also the Sahia de Malha Bank, modern Portuguese: saia de malha, English: mesh skirt) or Mesh Skirt Bank, is one of the largest submerged ocean banks in the world, a part of the vast undersea Mascarene Plateau.
The Saya de Malha Bank lies northeast of Madagascar, southeast of Seychelles, and north of Nazareth Bank, the Cargados Carajos Shoals, and the island of Mauritius, and currently falls mostly under international waters. The closest land is tiny Agaléga (one of the Outer Islands of Mauritius), some 300 km (190 mi) further west, followed by the southern Seychellois island of Coëtivy, some 400 km (250 mi) northwest. Mauritius administers the whole Saya de Malha Bank as a portion of it lies within its exclusive economic zone.
The bank covers an area of 40,808 km2 (15,756 sq mi), [1] and is composed of two separate structures, the smaller North Bank (also called Ritchie Bank), and the huge South Bank. If the South Bank were recognized as a submerged atoll structure, it would be the largest of the world, almost three times the size of the Great Chagos Bank, commonly considered the largest atoll structure of the world. Even smaller North Bank would be one of the largest atolls worldwide. The North Bank and the South Bank appear to have different origins, since they are separated by a fault. The South Bank and the Great Chagos Bank were one single feature until about 64 to 69 million years ago, when an ocean ridge opened between them and started pushing them apart. [2]
The Saya de Malha Bank consists of a series of narrow shoals, with depths from 17 to 29 m (56 to 95 ft) on the rim. They are arranged in a semicircular manner, around a space, the former lagoon, about 73 m (240 ft) deep, which slopes on the Southeast. Some areas of the bank are shallow, less than 10 m (33 ft) below the surface. The banks are covered with sea grass interspersed with small coral reefs. Due to its remote location, the bank is among the least-studied shallow marine ecoregions on the planet. The banks are a breeding ground for humpback whales and blue whales.
The bank was formed 35 million years ago by the Réunion hotspot, and is composed of basaltic basal rock overlain with limestone. The limestone banks found on the plateau are the remnants of coral reefs. Millions of years ago, the bank was one or more mountainous volcanic islands, like present-day Mauritius and Réunion, which subsequently sank below the waves. Some of the banks may have been low islands as recently as 18,000-6,000 years ago, when sea levels were up to 130 m (430 ft) lower during the most recent ice age.
The bank was named by Portuguese explorers 500 years ago, who encountered the bank on the voyage between the Cape of Good Hope and India. After traversing miles of deep blue Indian Ocean, they found themselves sailing above a shallow area of the bank, covered with swaying green seagrass.
The first scientific survey of the bank was undertaken by Captain Robert Moresby of the Royal Navy in 1838. Moresby previously surveyed the Laccadives, the Red Sea, the Maldives and the Chagos Banks. Due to Moresby's ill health, the Saya de Malha bank was his last survey in a long and brilliant career exploring and charting the archipelagos and reefs of the Indian Ocean. [3]
The Saya de Malha Bank is the site of an attempt to create an artificial island by Prof. Wolf Hilbertz (1938-2007) and Dr. Thomas J. Goreau. Hilbertz created seacrete or biorock by utilizing electricity to accrete the minerals in sea water onto a metal structure. The artificial coral thus far created has high enough tensile strength to be used as building material. With others, Hilbertz and Goreau made two expeditions to the bank in 1997 and 2002. [4] They attempted to create or grow an island around a steel structure that has been anchored to the North Bank sea floor at a depth of 11 m (36 ft). Some sources say that the island would have been named Autopia [5] or Autopia Saya, and declared a micronation.
Excerpt from an online interview with Wolf Hilbertz in Celestopea Times, 2004:
You and your discovery of accreting minerals in seawater into solid forms has inspired several groups over the years to contemplate creating artificial islands for their piece of paradise. Your name has been linked to some such as Autopia Ampere and Skerki Bank. Is there an update on either of those projects or words of encouragement for others seeking something similar?
Examining the geography and bathymetry of the globe to find a spot in the ocean where to establish a permanent research settlement I came upon Seamount Ampere, east of Gibraltar, and Skerki Bank near Sicily. Both sites had potential, but Saya de Malha Banks in the NE Indian Ocean eclipsed them all. Having about the size of Belgium, most of Saya lies in international waters, 'in the high seas' legally speaking, governed only by the U.N. Law of the Sea. In 1997, Goreau and I sailed to Saya de Malha's many shallow sites and established the first accretion structure there, powered by floating photovoltaics and thus claiming the banks. In 2002 the second Saya de Malha Expedition with three boats laid the foundation of Autopia Saya, powered by photovoltaics, and performed the first modern bathymetric surveys ever conducted in the area. The latest Saya de Malha Expedition Report is on our websites. We are busy now organizing a third expedition to get Autopia Saya growing above sea level.
Mauritius claims part of the Saya de Malha Bank as part of its exclusive economic zone. [6]
This is a list of the lists of islands in the world grouped by country, by continent, by body of water, and by other classifications. For rank-order lists, see the other lists of islands below.
The Mascarene Islands or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of La Réunion. Their name derives from the Portuguese navigator Pedro Mascarenhas, who first visited them in April 1512. The islands share a common geological origin beneath the Mascarene Plateau known as the Mauritia (microcontinent) which was a Precambrian microcontinent situated between India and Madagascar until their separation about 70 million years ago. They form a distinct ecoregion with unique biodiversityand endemism of flora and fauna.
The Maldives are formed by 20 natural atolls, along with a few islands and isolated reefs today which form a pattern stretching from 7 degrees 10′ North to 0 degrees 45′ South. The largest of these atolls is Boduthiladhunmathi, while the atoll containing the most islands is Huvadhu.
The Chagos Archipelago or Chagos Islands is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives archipelago. This chain of islands is the southernmost archipelago of the Chagos–Laccadive Ridge, a long submarine mountain range in the Indian Ocean. In its north are the Salomon Islands, Nelsons Island and Peros Banhos; towards its south-west are the Three Brothers, Eagle Islands, Egmont Islands and Danger Island; southeast of these is Diego Garcia, by far the largest island. All are low-lying atolls, save for a few extremely small instances, set around lagoons.
Peros Banhos, Pedro dos Banhos or Baixos de Pêro dos Banhos in old maps, is a formerly inhabited atoll in the Chagos Archipelago of the British Indian Ocean Territory, also claimed by Mauritius.
The British Indian Ocean Territory (BIOT) is an archipelago of 55 islands in the Indian Ocean, located south of India. It is situated approximately halfway between Africa and Indonesia. The islands form a semicircular group with an open sea towards the east. The largest, Diego Garcia, is located at the southern extreme end. It measures 60 square kilometres (23 sq mi) and accounts for almost three-quarters of the total land area of the territory. Diego Garcia is the only inhabited island and is home to the joint UK-US naval support facility. Other islands within the archipelago include Danger Island, Three Brothers Islands, Nelson Island, and Peros Banhos, as well as the island groups of the Egmont Islands, Eagle Islands, and the Salomon Islands.
Eagle Islands is a group of two islands in the Chagos Archipelago. They are located on the central-western rim of the Great Chagos Bank, which is the world's largest coral atoll structure.
Danger Island is the westernmost and the southernmost island of the Great Chagos Bank, which is the world's largest coral atoll structure, located in the Chagos Archipelago in the Indian Ocean.
Egmont Islands is an uninhabited atoll administered by the United Kingdom. They are one of the few emerged coral atolls that make up the Chagos Archipelago, British Indian Ocean Territory.
Nelsons Island or Nelson Island or Isle Legour is a small uninhabited island in the Great Chagos Bank, of the Chagos Archipelago in the Indian Ocean. As a protected nature reserve, access to the island is strictly restricted.
The Mascarene Plateau is a submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately 2,000 km (1,200 mi), from Seychelles in the north to Réunion in the south. The plateau covers an area of over 115,000 km2 (44,000 sq mi) of shallow water, with depths ranging from 8–150 m (30–490 ft), plunging to 4,000 m (13,000 ft) to the abyssal plain at its edges.
Blenheim Reef is a partly submerged atoll structure in the Chagos Archipelago, Indian Ocean. It includes the coral reef of Baxio Predassa in its southeastern rim, plus another completely submerged part. It is located in the northeastern part of the Chagos Archipelago. It measures almost eleven kilometres (north–south) by more than four kilometres (east–west), with a total area of 36.8 square kilometres, including the lagoon of 8.5 km2, the difference being accounted for the mostly by the reef flat. Only on the eastern side, there are a few sand cays above the water. The largest of them is East Island, which is not quite 200 metres long and 70 metres wide. The other islands in the group are North, Middle and South. Only a few grasses grow on the island. The lagoon is up to 18 metres deep and encumbered with rock. The fringing coral reef has a wide passage in the southwest. The closest land is Takamaka Island in the Salomon Islands Atoll, about 20 kilometres to the southwest.
Nazareth Bank is a large submerged bank in the Indian Ocean.
The Soudan Banks are a series of underwater high points and reefs off the coast of Africa, known for their good fishing yields as fishing banks. They are administered by Mauritius. The five banks lie on the Mascarene plateau. North Soudan contains large salmon stocks. South Soudan is the largest of the banks, with many reefs and passes. West Soudan is small, rocky, and shallow, and is the least fished of the banks. Central Soudan is the most fished area, with huge reefs and open waters containing a huge abundance of fish. East Soudan, until the 1970s, was considered to be a completely different formation altogether, since it is located more than 100 miles away from the other banks. The other banks are closely linked, separated by small shallows or channels.
An ocean bank, sometimes referred to as a fishing bank or simply bank, is a part of the seabed that is shallow compared to its surrounding area, such as a shoal or the top of an underwater hill. Somewhat like continental slopes, ocean bank slopes can upwell as tidal and other flows intercept them, sometimes resulting in nutrient-rich currents. Because of this, some large banks, such as Dogger Bank and the Grand Banks of Newfoundland, are among the richest fishing grounds in the world.
Robert Moresby was a captain of the East India Company's Bombay Marine/Indian Navy who distinguished himself as a hydrographer, maritime surveyor and draughtsman.
Wolf Hartmut Hilbertz was a German-born futurist architect, inventor, and marine scientist. Notable contributions to science include the discovery of artificial mineral accretetion / biorock and its use to create electrified reefs.
Biorock is a cement-like engineering material formed when a small electric current is passed between underwater metal electrodes placed in seawater causing dissolved minerals to accrete onto the cathode to form a thick layer of limestone. This 'accretion process' can be used to create building materials or to create artificial 'electrified reefs' for the benefit of corals and other sea-life. Discovered by Wolf Hilbertz in 1976, biorock was protected by patents and a trademark which have now expired.
Mauritia was a Precambrian microcontinent that was situated between India and Madagascar until their separation about 70 million years ago. Being initially attached to the Indian continent, Mauritia separated from it about 60 million years ago and further fragmented into a ribbon-like structure as the mid-ocean ridge jumped several times. The jumps of the mid-ocean ridge are thought to have been caused of its interaction with the Réunion hotspot as it passed under the West margin of the Indian continent and then under Mauritia. As of today, the fragments of Mauritia include the Laccadives–Maldives–Chagos Ridge, Nazareth Bank, the Saya de Malha Bank, and Hawkins Bank, as well as the islands of Réunion and Mauritius, where the continual crust is buried under basaltic lavas of the Réunion hotspot.
An electric reef is an artificial reef made from biorock, being limestone that forms rapidly in seawater on a metal structure from dissolved minerals in the presence of a small electric current. The first reefs of this type were created by Wolf Hilbertz and Thomas J. Goreau in the 1980s. By 2011 there were examples in over 20 countries.
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