From the tropics to the ice of Antarctica
Indian Ocean located between four continents - Eurasia (the Asian part of the continent) in the north, Antarctica in the south, Africa in the west and east with Australia and a group of islands and archipelagos located between the Indochina Peninsula and Australia.
Most of the Indian Ocean is located in the southern hemisphere. The border with the Atlantic Ocean is determined by a conventional line from Cape Agulhas (the southern point of Africa) along the 20th meridian to Antarctica. The border with the Pacific Ocean runs from the Malacca Peninsula (Indochina) to the northern point of Sumatra Island, then along the line. connecting the islands of Sumatra, Java, Bali, Sumba, Timor and New Guinea. The border between New Guinea and Australia runs through the Torres Strait, to the south of Australia - from Cape Howe to the island of Tasmania and along its western coast, and from Cape Yuzhny (the southernmost point of the island of Tasmania) strictly along the meridian to Antarctica. The Indian Ocean does not border the Arctic Ocean.
You can see a complete map of the Indian Ocean.
The area occupied by the Indian Ocean is 74,917 thousand sq. km - it is the third largest ocean. The ocean coastline is slightly indented, so there are few marginal seas on its territory. In its composition, only such seas can be distinguished as the Red Sea, the Persian and Bengal Bays (in fact, these are huge marginal seas), the Arabian Sea, the Andaman Sea, the Timor and Arafura Seas. The Red Sea is the internal sea of the basin, the rest are marginal.
The central part of the Indian Ocean consists of several deep-sea basins, among which the largest are the Arabian, Western Australian, and African-Antarctic. These basins are separated by extensive underwater ridges and uplifts. Deepest point Indian Ocean - 7130 m located in the Sunda Trench (along the Sunda island arc). The average depth of the ocean is 3897 m.
The bottom topography is quite uniform, the eastern part is smoother than the western. There are many shoals and banks in the area of Australia and Oceania. The bottom soil is similar to the soil of other oceans and consists of the following types: coastal sediments, organic silt (radiolar, diatomaceous earth) and clay at great depths (the so-called “red clay”). Coastal sediments are sand located in the shallows to a depth of 200-300 m. Silty sediments can be green, blue (near rocky coasts), brown (volcanic areas), lighter (due to the presence of lime) in areas of coral structures. Red clay occurs at depths greater than 4500 m. It has a red, brown, or chocolate color.
In terms of the number of islands, the Indian Ocean is inferior to all other oceans. The largest islands: Madagascar, Ceylon, Mauritius, Socotra and Sri Lanka are fragments of ancient continents. In the central part of the ocean there are groups of small islands of volcanic origin, and in tropical latitudes there are groups of coral islands. Most famous bands islands: Amirante, Seychelles, Comorno, Reunion, Maldives, Cocos.
Water temperature In the ocean, climate zones determine currents. The cold Somali Current lies off the coast of Africa, here the average water temperature is +22-+23 degrees C, in the northern part of the ocean the temperature of the surface layers can rise to +29 degrees C, at the equator - +26-+28 degrees C, according to As you move south, it drops to -1 degrees C off the coast of Antarctica.
The flora and fauna of the Indian Ocean are rich and diverse. Many tropical coasts are mangroves, where special communities of plants and animals have formed, adapted to regular flooding and drying. Among these animals one can note numerous crabs and an interesting fish - the mudskipper, which inhabits almost all the mangroves of the ocean. Shallow tropical waters are favored by coral polyps, including many reef-building corals, fish and invertebrates. In temperate latitudes, in shallow waters, red and brown algae grow in abundance, among which the most numerous are kelp, fucus and giant macrocysts. Phytoplankton is represented by peridinians in tropical waters and diatoms in temperate latitudes, as well as blue-green algae, which form dense seasonal aggregations in some places.
Among the animals living in the Indian Ocean, the largest number of crustaceans are rootworms, of which there are over 100 species. If you weigh all the rootpods in the waters of the ocean, their total mass will exceed the mass of all its other inhabitants.
Invertebrate animals are represented by various mollusks (pteropods, cephalopods, valves, etc.). There are a lot of jellyfish and siphonophores. In the waters of the open ocean, as in the Pacific Ocean, there are numerous flying fish, tuna, coryphaenas, sailfish and luminous anchovies. There are many sea snakes, including poisonous ones, and there is even a saltwater crocodile, which is prone to attacking people.
Mammals are represented in large numbers and diversity. There are whales here too different types, and dolphins, and killer whales, and sperm whales. Many pinnipeds (fur seals, seals, dugongs). Cetaceans are especially numerous in the cold southern waters of the ocean, where krill feeding grounds are located.
Among those living here sea birds frigates and albatrosses can be noted, and in cold and temperate waters - penguins.
Despite the richness of the animal world of the Indian Ocean, fishing and fishing in this region are poorly developed. The total catch of fish and seafood in the Indian Ocean does not exceed 5% of the world catch. Fisheries are represented only by tuna fishing in the central part of the ocean and by small fishing cooperatives and individual fishermen of the coasts and island regions.
In some places (off the coast of Australia, Sri Lanka, etc.) pearl mining is developed.
There is also life in the depths and bottom layer of the central part of the ocean. In contrast to the upper layers, which are more adapted for the development of flora and fauna, the deep-sea areas of the ocean are represented by a smaller number of individuals of the animal world, but in terms of species they are superior to the surface. Life in the depths of the Indian Ocean has been studied very little, as well as the depths of the entire World Ocean. Only the contents of deep-sea trawls, and rare dives of bathyscaphes and similar vehicles into multi-kilometer abysses, can approximately tell about the local life forms. Many forms of animals living here have body shapes and organs that are unusual to our eyes. Huge eyes, a toothy head larger than the rest of the body, bizarre fins and outgrowths on the body - all this is the result of animals adapting to life in conditions of pitch darkness and monstrous pressures in the depths of the ocean.
Many animals use luminous organs or light emitted by certain benthic microorganisms (benthos) to attract prey and protect themselves from enemies. Thus, the small (up to 18 cm) Platytroct fish, found in the deep-sea zones of the Indian Ocean, uses glow for protection. In moments of danger, she can blind the enemy with a cloud of glowing mucus and escape safely. Many living creatures that live in the dark abysses of the deep oceans and seas have similar weapons. The great white shark. There are many shark-hazardous places in the Indian Ocean. Off the coast of Australia, Africa, the Seychelles, the Red Sea, and Oceania, shark attacks on people are not uncommon.
There are many other animals dangerous to humans in the Indian Ocean. Poisonous jellyfish, blue-ringed octopus, cone clams, tridacnas, poisonous snakes, etc. can cause serious trouble for a person when communicating.
The following pages will tell you about the seas that make up the Indian Ocean, about the flora and fauna of these seas, and, of course, about the sharks that live in them.
Let's start with the Red Sea - a unique inland body of water in the Indian Ocean basin
The Indian Ocean has the least number of seas compared to other oceans. In the northern part there are the most large seas: Mediterranean - the Red Sea and the Persian Gulf, the semi-enclosed Andaman Sea and the marginal Arabian Sea; in the eastern part - the Arafura and Timor Seas.
There are relatively few islands. The largest of them are of continental origin and are located near the coasts of Madagascar, Sri Lanka, Socotra. In the open part of the ocean there are volcanic islands - Mascarene, Crozet, Prince Edward, etc. In tropical latitudes, coral islands rise on volcanic cones - the Maldives, Laccadives, Chagos, Cocos, most Andaman, etc.
Shores on the north-west. and the East are indigenous, in the north-east. and in the West, alluvial deposits predominate. The coastline is slightly indented, with the exception of the northern part of the Indian Ocean. Almost all seas and large bays (Aden, Oman, Bengal) are located here. In the southern part there are the Gulf of Carpentaria, the Great Australian Gulf and the Gulfs of Spencer, St. Vincent, etc.
A narrow (up to 100 km) continental shelf (shelf) stretches along the coast, the outer edge of which has a depth of 50-200 m (only in Antarctica and northwestern Australia up to 300-500 m). The continental slope is a steep (up to 10-30°) ledge, in places dissected by the underwater valleys of the Indus, Ganges, and other rivers. In the northeastern part of the ocean is the Sunda Island Arc and the associated Sunda Trench, which is associated with maximum depths (up to 7130 m). The bed of the Indian Ocean is divided by ridges, mountains and swells into a number of basins, the most significant of which are the Arabian Basin, the Western Australian Basin, and the African-Antarctic Basin. The bottom of these basins is formed by accumulative and hilly plains; the former are located near continents in areas with an abundant supply of sedimentary material, the latter - in the central part of the ocean. Among the numerous ridges of the bed, the meridional East Indian Ridge, which connects in the south with the latitudinal Western Australian Ridge, stands out due to its straightness and length (about 5,000 km); large meridional ridges stretch south from the Hindustan Peninsula and the island. Madagascar. Volcanoes are widely represented on the ocean floor (Mt. Bardina, Mt. Shcherbakova, Mt. Lena, etc.), which in some places form large massifs (to the north of Madagascar) and chains (to the east of the Cocos Islands). Mid-ocean ridges are a mountain system consisting of three branches diverging from the central part of the ocean to the north (Arabian-Indian ridge), southwest. (West Indian and African-Antarctic ridges) and South-East. (Central Indian Ridge and Australian-Antarctic Rise). This system has a width of 400-800 km, a height of 2-3 km and is most dissected by an axial (rift) zone with deep valleys and rift mountains bordering them; Characterized by transverse faults, along which horizontal displacements of the bottom up to 400 km are noted. The Australian-Antarctic Rise, in contrast to the median ridges, is a more gentle swell 1 km high and up to 1500 km wide.
Bottom sediments of the Indian Ocean are thickest (up to 3-4 km) at the foot of the continental slopes; in the middle of the ocean - small (about 100 m) thickness and in places where dissected relief is distributed - intermittent distribution. The most widely represented are foraminifera (on continental slopes, ridges and on the bottom of most basins at depths of up to 4700 m), diatoms (south of 50° S), radiolarians (near the equator) and coral sediments. Polygenic sediments - red deep-sea clays - are common south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of continents. Chemogenic sediments are represented mainly by iron-manganese nodules, and riftogenic sediments are represented by products of destruction of deep rocks. Outcrops of bedrock are most often found on continental slopes (sedimentary and metamorphic rocks), mountains (basalts) and mid-ocean ridges, where, in addition to basalts, serpentinites and peridotites, representing the slightly altered material of the Earth's upper mantle, were found.
The Indian Ocean is characterized by the predominance of stable tectonic structures both on the bed (thalassocratons) and along the periphery (continental platforms); active developing structures - modern geosynclines (Sunda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and are continued in the corresponding structures of Indochina and rifts East Africa. These main macrostructures, sharply different in morphology, structure earth's crust, seismic activity, volcanism, are divided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, block ridges, volcanic ridges, in places topped with coral islands and banks (Chagos, Maldives, etc.), fault trenches (Chagos, Obi, etc. .), often confined to the foot of blocky ridges (East Indian, Western Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the Indian Ocean bed, the Northern part The Mascarene Ridge is a structure that appears to be part of the ancient continent of Gondwana.
Minerals: on the shelves - oil and gas (especially the Persian Gulf), monazite sands (coastal region of South-West India), etc.; in rift zones - ores of chromium, iron, manganese, copper, etc.; on the bed there are huge accumulations of iron-manganese nodules.
The climate of the northern Indian Ocean is monsoonal; in summer, when the region develops over Asia low blood pressure, southwestern equatorial air flows dominate here, and in winter - northeastern tropical air flows. To the south 8-10° S. w. atmospheric circulation is much more constant; Here, in tropical (summer and subtropical) latitudes, stable southeastern trade winds dominate, and in temperate latitudes, extratropical cyclones moving from West to East dominate. In tropical latitudes in the western part there are hurricanes in summer and autumn. The average air temperature in the northern part of the ocean in summer is 25-27 °C, off the coast of Africa - up to 23 °C. In the southern part it drops in summer to 20-25 °C at 30° S. latitude, up to 5-6 °C at 50° S. w. and below 0 °C south of 60 ° S. w. In winter, the air temperature varies from 27.5 °C at the equator to 20 °C in the northern part, to 15 °C at 30 ° S. latitude, up to 0-5 °C at 50° S. w. and below 0 °C south of 55-60 ° S. w. Moreover, in the southern subtropical latitudes all year round, the temperature in the West, under the influence of the warm Madagascar Current, is 3-6 °C higher than in the East, where the cold Western Australian Current exists. Cloudiness in the monsoon northern part of the Indian Ocean is 10-30% in winter, up to 60-70% in summer. In summer, the greatest amount of precipitation is observed here. The average annual precipitation in the east of the Arabian Sea and the Bay of Bengal is more than 3000 mm, at the equator 2000-3000 mm, in the west of the Arabian Sea up to 100 mm. In the southern part of the ocean, the average annual cloudiness is 40-50%, south of 40° S. w. - up to 80%. The average annual precipitation in the subtropics is 500 mm in the east, 1000 mm in the west, in temperate latitudes it is more than 1000 mm, and near Antarctica it drops to 250 mm.
The circulation of surface waters in the northern part of the Indian Ocean has a monsoon character: in summer - northeastern and eastern currents, in winter - southwestern and western currents. In the winter months between 3° and 8° S. w. The inter-trade wind (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the Southern Trade Winds in the north, Madagascar and Agulhas in the West and cold currents - the Western Winds current in the South and Western Australian in the East South of 55 ° S. w. Several weak cyclonic water circulations develop, closing off the coast of Antarctica with an eastern current.
The positive component predominates in the heat balance: between 10° and 20° N. w. 3.7-6.5 GJ/(m2×year); between 0° and 10° S. w. 1.0-1.8 GJ/(m2×year); between 30° and 40° S. w. - 0.67-0.38 GJ/(m2×year) [from - 16 to 9 kcal/(cm2×year)]; between 40° and 50° S. w. 2.34-3.3 GJ/(m2×year); south of 50° S. w. from -1.0 to -3.6 GJ/(m2×year) [from -24 to -86 kcal/(cm2×year)]. In the expenditure part of the heat balance north of 50° S. w. the main role belongs to the loss of heat for evaporation, and south of 50° south. w. - heat exchange between the ocean and the atmosphere.
Surface water temperatures reach a maximum (over 29 °C) in May in the northern part of the ocean. In the summer of the Northern Hemisphere it is 27-28 °C here and only off the coast of Africa it decreases to 22-23 °C under the influence of cold waters coming to the surface from the depths. At the equator the temperature is 26-28 °C and decreases to 16-20 °C at 30° south. latitude, up to 3-5 °C at 50° S. w. and below -1 °C south of 55° S. w. In the winter of the Northern Hemisphere, the temperature in the north is 23-25 °C, at the equator 28 °C, at 30 ° S. w. 21-25 °C, at 50° S. w. from 5 to 9 °C, south of 60° S. w. temperatures are negative. In subtropical latitudes all year round in the West, the water temperature is 3-5 °C higher than in the East.
The salinity of water depends on the water balance, which is formed on average for the surface of the Indian Ocean from evaporation (-1380 mm/year), precipitation (1000 mm/year) and continental runoff (70 cm/year). The main flow of fresh water comes from the rivers of South Asia (Ganges, Brahmaputra, etc.) and Africa (Zambezi, Limpopo). The highest salinity is observed in the Persian Gulf (37-39‰), in the Red Sea (41‰) and in the Arabian Sea (more than 36.5‰). In the Bay of Bengal and the Andaman Sea it decreases to 32.0-33.0‰, in the southern tropics - to 34.0-34.5‰. In southern subtropical latitudes, salinity exceeds 35.5‰ (maximum 36.5‰ in summer, 36.0‰ in winter), and to the south 40° S. w. decreases to 33.0-34.3‰. The highest water density (1027) is observed in Antarctic latitudes, the lowest (1018, 1022) in the northeastern part of the ocean and in the Bay of Bengal. In the northwestern part of the Indian Ocean, the density of water is 1024-1024.5. The oxygen content in the surface layer of water increases from 4.5 ml/l in the northern part of the Indian Ocean to 7-8 ml/l south of 50° south. w. At depths of 200-400 m, the oxygen content in absolute value is significantly lower and varies from 0.21-0.76 in the north to 2-4 ml/l in the south; at greater depths it gradually increases again and in the bottom layer is 4.03 -4.68 ml/l. The color of the water is predominantly blue, in Antarctic latitudes it is blue, in places with greenish tints.
Tides in the Indian Ocean, as a rule, are small (off the coast of the open ocean and on the islands from 0.5 to 1.6 m), only at the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semidiurnal.
Ice forms in high latitudes and is carried by winds and currents along with icebergs in a northerly direction (up to 55° S in August and up to 65-68° S in February).
Deep circulation and vertical structure The Indian Ocean is formed by waters plunging into the subtropical (subsurface waters) and Antarctic (intermediate waters) convergence zones and along the continental slope of Antarctica (bottom waters), as well as coming from the Red Sea and the Atlantic Ocean (deep waters). At a depth of 100-150 m to 400-500 m, subsurface waters have a temperature of 10-18°C, a salinity of 35.0-35.7‰, intermediate waters occupy a depth of 400-500 m to 1000-1500 m, and have a temperature of 4 to 10°C, salinity 34.2-34.6‰; deep waters at depths from 1000-1500 m to 3500 m have a temperature of 1.6 to 2.8 ° C, salinity 34.68-34.78‰; Bottom waters below 3500 m have a temperature from -0.07 to -0.24 ° C in the South, a salinity of 34.67-34.69‰, in the North - about 0.5 ° C and 34.69-34.77 ‰ respectively.
Flora and fauna
The entire Indian Ocean lies within the tropical and southern temperate zones. The shallow waters of the tropical zone are characterized by numerous 6- and 8-rayed corals and hydrocorals, which, together with calcareous red algae, can create islands and atolls. Among the powerful coral structures lives a rich fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral fish. Most of the coasts are occupied by mangroves, in which the mudskipper, a fish capable of long time exist in the air. The fauna and flora of beaches and cliffs that dry out at low tide are quantitatively depleted as a result of the inhibitory effect sun rays. In the temperate zone, life on such sections of the coast is much richer; Dense thickets of red and brown algae (kelp, fucus, reaching enormous sizes of macrocystis) develop here, and a variety of invertebrates are abundant. The open spaces of the Indian Ocean, especially the surface layer of the water column (up to 100 m), are also characterized by a rich flora. Of the unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause so-called water blooms when they develop en masse.
The bulk of ocean animals are copepod crustaceans (more than 100 species), followed by pteropods, jellyfish, siphonophores and other invertebrate animals. The most common unicellular organisms are radiolarians; Squids are numerous. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, coryphaenas, large and small tuna, sailfish and various sharks, poisonous sea snakes. Sea turtles and large marine mammals (dugongs, toothed and toothless whales, pinnipeds) are common. Among the birds, the most characteristic are albatrosses and frigatebirds, as well as several species of penguins that inhabit the coasts South Africa, Antarctica and islands lying in the temperate zone of the ocean.
Indian Ocean- the warmest ocean on our planet. Occupying a fifth of the Earth's surface, the Indian Ocean is not the largest ocean, but it has rich flora and fauna, as well as a lot of other advantages.
Indian Ocean
Indian Ocean occupies 20% of the entire globe. This ocean is characterized by rich and diverse natural life. 
shows vast territories and a large number of interesting islands for researchers and tourists. If you don't yet know where it is located Indian Ocean map will tell you.
Indian Ocean Current Map
The underwater world of the Indian Ocean
Rich and varied underwater world of the Indian Ocean. In it you can find both very small aquatic inhabitants and large and dangerous representatives of the aquatic world.
Since ancient times, man has been trying to subjugate the ocean and its inhabitants. In all ages on the inhabitants underwater world There was a hunt going on in the Indian Ocean.
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There are even those that can cause trouble for a person. For example, these are sea anemones that live in almost all the seas and oceans of our planet. Sea anemones can be found not only in the depths, but also in the shallow waters of the Indian Ocean. They almost always feel hungry, so they sit hidden with their tentacles widely spaced. Predatory representatives of this species are poisonous. Their shot can hit small organisms and also cause burns in people. Sea urchins, seals, and the most exotic species of fish live in the waters of the Indian Ocean. The flora is diverse, which makes diving truly exciting.
Fishes in the Indian Ocean
What is the area of the Indian Ocean? The very name of the water area implies quite large numbers. It is immediately worth paying attention to the fact that the Indian Ocean ranks third in size among similar bodies of water on our planet. In the widest part of the ocean, the distance is about 10 thousand km. This meaning visually connects the southern points of Africa and Australia. It is located between four continents: Antarctica, Eurasia, Africa and Australia. So, what is the area of the Indian Ocean (million km2)? This figure is 76.174 million square meters. km.
Let's look into history
The Indian Ocean in the north cuts so far into the land that people ancient world defined it as a very large sea. It was in these waters that humanity began its first long journeys.
On ancient maps it (or rather, the western part) was called the “Eritrean Sea”. And the ancient Russians called him Black. In the 4th century, a name consonant with the current one began to appear for the first time: the Greek “Indikon pelagos” - “Indian Sea”, the Arabic Bar-el-Hind - “Indian Ocean”. And already in the 16th century, the hydronym, which was proposed by a Roman scientist, was officially assigned to the ocean.
Geography
The Indian Ocean, whose area is smaller than the Pacific and Atlantic, is younger and much warmer than these bodies of water. This body of water receives many rivers in the region, the largest of which are the Limpopo, Tigris, Ganges and Euphrates. The near-continental waters of the ocean are muddy due to the abundance of clay and sand that rivers carry into them, but its open water is surprisingly clean. There are many islands in the Indian Ocean. Some of them are debris. The largest are Madagascar, Sri Lanka, Comoros, Maldives, Seychelles and many others.
The Indian Ocean has seven seas and six bays, as well as several straits. Their area is more than 11 million square meters. km. The most famous are the Red Sea (the saltiest in the world), the Arabian Sea, the Andaman Sea, the Persian Sea and
The ocean sits above ancient tectonic plates that are still moving today. Because of this, tsunamis and underwater volcanic eruptions are common in the region.
Climate indicators
The Indian Ocean, whose area is more than 76 million square meters. km, located in four climatic zones. The north of the water basin is influenced by the Asian continent, which is why frequent tsunamis with characteristic characteristics are observed here. high temperatures The water heats up well, so the seas and bays there are the warmest. In the south, the southeast trade wind prevails with its cold air. Tropical hurricanes often form in the middle part.
The entire weather background is formed by monsoons - winds that change direction depending on the season. There are two of them: summer - hot and rainy and winter, with sudden changes weather, often accompanied by storms and floods.
World of flora and fauna
The Indian Ocean, whose area is quite large, has an extremely diverse fauna and flora, both on land and in the aquatic part. The tropics are rich in plankton, which, unlike the Pacific, is abundant in luminous organisms. A huge number of crustaceans, jellyfish and squid. The most common fish are flying species, poisonous sea snakes, tuna, and some types of sharks. In the waters you can see whales, seals and dolphins. The coast is favored by giant turtles and elephant seals.
Among the variety of birds, albatross and frigatebirds can be distinguished. And in southern Africa there are various populations of penguins. Corals grow in shallow waters, sometimes forming entire islands. Among these beautiful structures live many representatives of this region - sea urchin and starfish, crabs, sponges, coral fish.
Like any other body of water, the Indian Ocean abounds in numerous species of algae. For example, sargassum, which is also found in the Pacific region. There are also lush and strong lithothamnias and halimedas, which help the corals build atolls, turbinaria and caulerpas, forming entire underwater jungles. The tidal zone is favored by mangroves - dense, always green forests.
Economic characteristics of the Indian Ocean
The Indian Ocean is shared by 28 mainland and 8 island states. With some on the brink of extinction, what was once a highly developed species is fading away. Fishing takes up a small percentage of the economy of this region. Mother-of-pearl and pearls are mined off the coast of Australia, Bahrain and Sri Lanka.
The ocean is the largest transport artery for ships in the region. The main maritime transport hub is the Suez Canal, connecting the Indian Ocean with the Atlantic. From there the path to Europe and America opens. Almost most of the region's business life is concentrated in port cities - Mumbai, Karachi, Durban, Colombo, Dubai and others.
With an area of over 76 million km2, the Indian Ocean is home to a huge number of mineral deposits. Huge deposits of non-ferrous metals and ores. But the main wealth, of course, is the richest oil and gas deposits. They are concentrated mainly on the shallows of the Persian and Suez Gulfs.
Unfortunately, human activity is becoming a threat to the integrity and preservation of this world. Across the Indian Ocean large quantities tankers and industrial vessels ply. Any leak, even a small one, can become a disaster for the entire region.
Introduction
1.History of the formation and exploration of the Indian Ocean
2.General information about the Indian Ocean
Bottom relief.
.Characteristics of the waters of the Indian Ocean.
.Bottom sediments of the Indian Ocean and its structure
.Minerals
.Indian Ocean climate
.Flora and fauna
.Fisheries and marine activities
Introduction
Indian Ocean- the youngest and warmest among the world's oceans. Most of it is located in the southern hemisphere, and in the north it extends far into the mainland, which is why ancient people considered it simply big sea. It was here, in the Indian Ocean, that man began his first sea voyages.
The largest rivers in Asia belong to the Indian Ocean basin: the Salween, the Irrawaddy and the Ganges with the Brahmaputra, which flow into the Bay of Bengal; Indus, flowing into the Arabian Sea; The Tigris and Euphrates merge slightly above their confluence with the Persian Gulf. Of the large rivers in Africa that also flow into the Indian Ocean, the Zambezi and Limpopo should be mentioned. Because of them, the water off the ocean coast is cloudy, with a high content of sedimentary rocks - sand, silt and clay. But the open waters of the ocean are amazingly clear. The tropical islands of the Indian Ocean are famous for their cleanliness. A variety of animals have found their home on coral reefs. The Indian Ocean is home to the famous sea devils, rare whale sharks, largemouths, sea cows, sea snakes, etc.
1. History of formation and research
Indian Oceanformed at the junction of the Jurassic and Cretaceous periods as a result of the collapse of Gondwana (130-150 million years ago). Then there was a separation of Africa and the Deccan from Australia with Antarctica, and later - of Australia from Antarctica (in the Paleogene, about 50 million years ago).
The Indian Ocean and its shores remain poorly studied. The name of the Indian Ocean appears already at the beginning of the 16th century. by Schöner under the name Oceanus orientalis indicus, in contrast to the Atlantic Ocean, then known as Oceanus occidentalis. Subsequent geographers called the Indian Ocean for the most part the Indian Sea, some (Varenius) the Australian Ocean, and Fleuriet recommended (in the 18th century) to even call it the Great Indian Gulf, considering it as part of the Pacific Ocean.
In ancient times (3000-1000 BC), sailors from India, Egypt and Phenicia traveled through the northern part of the Indian Ocean. The first navigation maps were compiled by the ancient Arabs. At the end of the 15th century, the first European, the famous Portuguese Vasco da Gama, circumnavigated Africa from the south and entered the waters of the Indian Ocean. By the 16th-17th centuries, Europeans (the Portuguese, and later the Dutch, French and English) increasingly appeared in the Indian Ocean basin, and by the middle of the 19th century, most of its shores and islands were already the property of Great Britain.
History of discoverycan be divided into 3 periods: from ancient voyages to 1772; from 1772 to 1873 and from 1873 to the present. The first period is characterized by the study of the distribution of ocean and land waters in this part of the globe. It began with the first voyages of Indian, Egyptian and Phoenician sailors, who 3000-1000 BC. traveled through the northern part of the Indian Ocean, and ended with the voyage of J. Cook, who in 1772-75 penetrated the South to 71° S. w.
The second period was marked by the beginning of deep-sea exploration, first carried out by Cook in 1772 and continued by Russian and foreign expeditions. The main Russian expeditions were O. Kotzebue on the Rurik (1818) and Pallena on the Cyclone (1858-59).
The third period is characterized by complex oceanographic research. Until 1960 they were carried out on separate ships. The largest works were carried out by expeditions on the ships "Challenger" (English) in 1873-74, "Vityaz" (Russian) in 1886, "Valdivia" (German) in 1898-99 and "Gauss" (German) in 1901-03, Discovery II (English) in 1930-51, the Soviet expedition to the Ob in 1956-58, etc. In 1960-65, the Intergovernmental Oceanographic Expedition under UNESCO carried out an international Indian Ocean expedition, which collected new valuable data on hydrology, hydrochemistry, meteorology , geology, geophysics and biology of the Indian Ocean.
. General information
Indian Ocean- the third largest ocean on Earth (after the Pacific and Atlantic), covering about 20% of its water surface. Almost all of it is located in the southern hemisphere. Its area is 74917 thousand km ² ; average volume of water - 291945 thousand km ³. In the north it is bounded by Asia, in the west by the Arabian Peninsula and Africa, in the east by Indochina, the Sunda Islands and Australia, and in the south by the Southern Ocean. The border between the Indian and Atlantic Oceans runs along the 20° meridian of eastern longitude (Meridian of Cape Agulhas), between the Indian and Pacific Oceans runs along the 147° meridian of east longitude (meridian of the southern cape of Tasmania). The northernmost point of the Indian Ocean is located at approximately 30°N latitude in the Persian Gulf. The Indian Ocean is approximately 10,000 km wide between the southern points of Australia and Africa.
The greatest depth of the Indian Ocean is the Sunda or Java Trench (7729 m), the average depth is 3700 m.
The Indian Ocean washes three continents at once: Africa from the east, Asia from the south, Australia from the north and northwest.
The Indian Ocean has the least number of seas compared to other oceans. In the northern part there are the largest seas: the Mediterranean - the Red Sea and the Persian Gulf, the semi-enclosed Andaman Sea and the marginal Arabian Sea; in the eastern part - the Arafura and Timor Seas.
In the Indian Ocean are the island states of Madagascar (the fourth largest island in the world), Sri Lanka, Maldives, Mauritius, Comoros, and Seychelles. The ocean washes the following states in the east: Australia, Indonesia; in the northeast: Malaysia, Thailand, Myanmar; in the north: Bangladesh, India, Pakistan; in the west: Oman, Somalia, Kenya, Tanzania, Mozambique, South Africa. In the south it borders with Antarctica. There are relatively few islands. In the open part of the ocean there are volcanic islands - Mascarene, Crozet, Prince Edward, etc. In tropical latitudes, coral islands rise on volcanic cones - the Maldives, Laccadives, Chagos, Cocos, most Andaman, etc.
. Bottom relief
The ocean floor is a system of mid-ocean ridges and basins. In the area of Rodriguez Island (Mascarene archipelago) there is a so-called triple junction, where the Central Indian and West Indian ridges, as well as the Australian-Antarctic Rise, converge. The ridges consist of steep mountain ranges, cut by faults perpendicular or oblique to the axes of the chains and divide the basalt ocean floor into 3 segments, and their peaks are, as a rule, extinct volcanoes. The bottom of the Indian Ocean is covered with sediments of the Cretaceous and later periods, the thickness of which varies from several hundred meters to 2-3 km. The deepest of the ocean's many trenches is the Java Trench (4,500 km long and 29 km wide). Rivers flowing into the Indian Ocean carry with them huge quantities of sediment, especially from India, creating high sediment thresholds.
The Indian Ocean coast is replete with cliffs, deltas, atolls, coastal coral reefs and salt marshes covered with mangroves. Some islands - for example, Madagascar, Socotra, the Maldives - are fragments of ancient continents. Numerous islands and archipelagos of volcanic origin are scattered in the open part of the Indian Ocean. In the northern part of the ocean, many of them are topped with coral structures. Andaman, Nicobar or Christmas Island - are of volcanic origin. The Kerguelen Plateau, located in the southern part of the ocean, is also of volcanic origin.
An undersea earthquake in the Indian Ocean on December 26, 2004 caused a tsunami that was considered the deadliest natural disaster in the world. modern history. The magnitude of the earthquake was, according to various estimates, from 9.1 to 9.3. This is the second or third strongest earthquake on record.
The epicenter of the earthquake was in the Indian Ocean, north of the island of Simeulue, located off the northwestern coast of the island of Sumatra (Indonesia). The tsunami reached the shores of Indonesia, Sri Lanka, southern India, Thailand and other countries. The height of the waves exceeded 15 meters. The tsunami caused enormous destruction and a huge number of dead people, even in Port Elizabeth, South Africa, 6900 km from the epicenter. According to various estimates, from 225 thousand to 300 thousand people died. The true death toll is unlikely to ever be known, as many people were swept out to sea.
As for the properties of the bottom soil, then, like in other oceans, sediments on the bottom of the Indian Ocean can be divided into three classes: coastal sediments, organic silt (globigerine, radiolar or diatom) and special clay of great depths, the so-called red clay. Coastal sediments are sand, located mostly on coastal shallows to a depth of 200 meters, green or blue silt near rocky shores, with a brown color in volcanic areas, but lighter and sometimes pinkish or yellowish near coral coasts due to the predominant lime. Globigerine mud, composed of microscopic foraminifera, covers the deeper parts of the ocean floor to a depth of almost 4500 m; south of the parallel 50° S. w. calcareous foraminiferal deposits disappear and are replaced by microscopic siliceous, from the group of algae, diatoms. In terms of the accumulation of diatom remains on the bottom, the southern Indian Ocean is particularly different from other oceans, where diatoms are found only locally. Red clay occurs at depths greater than 4500 m; it is red, or brown, or chocolate in color.
Indian Ocean climate fossil fisheries
4. Water characteristics
Surface water circulationin the northern part of the Indian Ocean it has a monsoon character: in summer - northeastern and eastern currents, in winter - southwestern and western currents. In the winter months between 3° and 8° S. w. The inter-trade wind (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the Southern Trade Wind in the North, Madagascar and Agulhas in the West and cold currents - the Western Winds in the South and Western Australian in the East South of 55° S. w. Several weak cyclonic water circulations develop, closing off the coast of Antarctica with an eastern current.
Indian Ocean water beltbetween 10 ° With. w. and 10 ° Yu. w. called the thermal equator, where the surface water temperature is 28-29°C. To the south of this zone the temperature drops, reaching about 1°C off the coast of Antarctica. In January and February, the ice along the coast of this continent melts, huge blocks of ice break off from the Antarctic ice sheet and drift towards the open ocean. To the north, the temperature characteristics of the waters are determined by the monsoon air circulation. In summer, temperature anomalies are observed here, when the Somali Current cools the surface waters to a temperature of 21-23°C. In the eastern part of the ocean on the same geographic latitude The water temperature is 28°C, and the highest temperature - about 30°C - was recorded in the Persian Gulf and the Red Sea. The average salinity of ocean waters is 34.8‰ The waters of the Persian Gulf, Red and Arabian Seas are the most saline: this is explained by intense evaporation with a small amount of fresh water brought into the seas by rivers.
Tides in the Indian Ocean, as a rule, are small (off the coast of the open ocean and on the islands from 0.5 to 1.6 m), only at the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semidiurnal.
Ice forms in high latitudes and is carried by winds and currents along with icebergs in a northerly direction (up to 55° S in August and up to 65-68 S in February).
. Bottom sediments of the Indian Ocean and its structure
Bottom sedimentsIndian Ocean have the greatest thickness (up to 3-4 km) at the foot of the continental slopes; in the middle of the ocean - small (about 100 m) thickness and in places where dissected relief is distributed - intermittent distribution. The most widely represented are foraminifera (on continental slopes, ridges and on the bottom of most basins at depths of up to 4700 m), diatoms (south of 50° S), radiolarians (near the equator) and coral sediments. Polygenic sediments - red deep-sea clays - are common south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of continents. Chemogenic sediments are represented mainly by ferromanganese nodules, and riftogenic sediments are represented by products of destruction of deep rocks. Outcrops of bedrock are most often found on continental slopes (sedimentary and metamorphic rocks), mountains (basalts) and mid-ocean ridges, where, in addition to basalts, serpentinites and peridotites, representing the slightly altered material of the Earth's upper mantle, were found.
The Indian Ocean is characterized by the predominance of stable tectonic structures both on the bed (thalassocratons) and along the periphery (continental platforms); active developing structures - modern geosynclines (Sunda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and are continued in the corresponding structures of Indochina and the rifts of East Africa. These main macrostructures, which differ sharply in morphology, crustal structure, seismic activity, volcanism, are divided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, block ridges, volcanic ridges, in places topped with coral islands and banks (Chagos, Maldives, etc. .), fault trenches (Chagos, Obi, etc.), often confined to the foot of blocky ridges (East Indian, Western Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the Indian Ocean bed, a special place (in terms of the presence of continental rocks - granites of the Seychelles Islands and the continental type of the earth's crust) is occupied by the northern part of the Mascarene Ridge - a structure that is, apparently, part of the ancient continent of Gondwana.
. Minerals
The most important mineral resources of the Indian Ocean are oil and natural gas. Their deposits are located on the shelves of the Persian and Suez Gulfs, in the Bass Strait, and on the shelf of the Hindustan Peninsula. The Indian Ocean ranks first in the world in terms of reserves and production of these minerals. Ilmenite, monazite, rutile, titanite and zirconium are exploited on the coasts of Mozambique, Madagascar and Ceylon. There are deposits of barite and phosphorite off the coast of India and Australia, and deposits of cassiterite and ilmenite are exploited on an industrial scale in the offshore zones of Indonesia, Thailand and Malaysia. On the shelves - oil and gas (especially the Persian Gulf), monazite sands (coastal region of South-West India), etc.; in reef zones - ores of chromium, iron, manganese, copper, etc.; on the bed there are huge accumulations of ferromanganese nodules.
. ClimateIndian Ocean
Most of the Indian Ocean is located in warm climate zones - equatorial, subequatorial and tropical. Only its southern regions, located at high latitudes, are strongly influenced by Antarctica. The equatorial climate zone of the Indian Ocean is characterized by the constant predominance of moist, warm equatorial air. Average monthly temperatures here range from 27° to 29°. The water temperature is slightly higher than the air temperature, which creates favorable conditions for convection and precipitation. Their annual amount is large - up to 3000 mm or more.
. Flora and fauna
The Indian Ocean is home to the most dangerous mollusks in the world - cone snails. Inside the snail there is a rod-like container with poison, which it injects into its prey (fish, worms); its poison is also dangerous for humans.
The entire Indian Ocean lies within the tropical and southern temperate zones. The shallow waters of the tropical zone are characterized by numerous 6- and 8-rayed corals and hydrocorals, which, together with calcareous red algae, can create islands and atolls. Among the powerful coral structures lives a rich fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral fish. Most of the coasts are occupied by mangroves, in which the mudskipper stands out - a fish that can exist in the air for a long time. The fauna and flora of beaches and rocks that dry out at low tide are quantitatively depleted as a result of the depressing effect of sunlight. In the temperate zone, life on such sections of the coast is much richer; Dense thickets of red and brown algae (kelp, fucus, reaching enormous sizes of microcystis) develop here, and a variety of invertebrates are abundant. The open spaces of the Indian Ocean, especially the surface layer of the water column (up to 100 m), are also characterized by a rich flora. Among unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause so-called water blooms when they develop en masse.
The bulk of ocean animals are crustaceans - copepods (more than 100 species), followed by pteropods, jellyfish, siphonophores and other invertebrate animals. The most common unicellular organisms are radiolarians; Squids are numerous. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, coryphaenas, large and small tuna, sailfish and various sharks, poisonous sea snakes. Sea turtles and large marine mammals (dugongs, toothed and toothless whales, pinnipeds) are common. Among the birds, the most typical are albatrosses and frigatebirds, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and islands lying in the temperate zone of the ocean.
At night, the surface of the Indian Ocean shimmers with lights. Light is produced by small marine plants called dinoflagellates. The glowing areas sometimes have the shape of a wheel with a diameter of 1.5 m.
. Fisheries and marine activities
Fishing is poorly developed (the catch does not exceed 5% of the world catch) and is limited to the local coastal zone. There is tuna fishing near the equator (Japan), and whale fishing in Antarctic waters. Pearls and mother-of-pearl are mined in Sri Lanka, the Bahrain Islands and the northwestern coast of Australia.
The countries of the Indian Ocean also have significant resources of other valuable types of mineral raw materials (tin, iron and manganese ores, natural gas, diamonds, phosphorites, etc.).
Bibliography:
1.Encyclopedia "Science" Dorling Kindersley.
.“I'm exploring the world. Geography" V.A. Markin
3.slovari.yandex.ru ~ TSB books / Indian Ocean /
4.Big encyclopedic Dictionary Brockhausa F.A., Efron I.A.
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