Islands of the southern half of the Indian Ocean. Indian Ocean: on the map, seas, currents, photo, islands, depressions, fish, geography, ecology, depth, size, area

Indian Ocean is the third largest ocean after the Pacific Ocean. The ocean is approximately 10,000 km wide between the southern tip of Africa and Australia; an area of ​​73,556,000 sq. km, including the Red Sea and the Persian Gulf. The volume of the ocean is approximately 292,131,000 cubic km.

Seas of the Indian Ocean: Andaman, Arabian, Arafura, Red, Laccadive, Timor

There are relatively few islands. The largest of them are of continental origin and are located near the coast: Madagascar, Sri Lanka, Socotra. In the open part of the ocean there are volcanic islands - Mascarene, Crozet, Prince Edward and others. In tropical latitudes, coral islands rise on volcanic cones - the Maldives, Laccadives, Chagos, Cocos, most of the Andaman and others.

Minerals: on the shelves - oil and gas (especially the Persian Gulf), monazite sands (the coastal region of Southwestern India), etc.; in rift zones - ores of chromium, iron, manganese, copper and others; on the bed - huge accumulations of ferromanganese nodules.

The surface water temperature reaches its maximum (over 29C) in May in the northern part of the ocean. In the summer of the Northern Hemisphere, it is here 27-28C and only off the coast of Africa decreases to 22-23C under the influence of cold waters coming to the surface from the depths. At the equator, the temperature is 26-28C and decreases to 16-20C at 30 south latitude, to 3-5 C at 50 south latitude and below -1C south of 55 south latitude. In the winter of the Northern Hemisphere, the temperature on the Sun is 23-25 C, at 30 south latitude 21-25 C, at 50 degrees south latitude from 5 to 9C, south of 60 south latitude 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 the southern subtropical latitudes, salinity exceeds 35.5% (maximum 36.5% in summer, 36.0% in winter), and south of 40% south latitude it drops to 33.0-34.3%.

The color of the water is predominantly blue, in the Antarctic latitudes it is blue, in some places with greenish hues.

The bulk of the ocean's animals are copepods (more than 100 species), followed by pteropods, jellyfish, siphonophores and other invertebrates. Of the unicellular, radiolarians are characteristic; numerous squids. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, dolphins, large and small tuna, sailfish and various sharks, poisonous sea snakes. common sea ​​turtles and major marine mammals(dugongs, toothed and toothless whales, pinnipeds). Among the birds, the most characteristic are albatrosses and frigatebirds, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and the islands lying in temperate zone ocean.

Fishing and marine industry. Fishing is underdeveloped (catch does not exceed 5% of the world catch) and is limited to local coastal zone. Near the equator (Japan) is fishing for tuna, and in Antarctic waters - whale fishing. In Sri Lanka, on the Bahrain Islands and on the northwestern coast of Australia, pearls and mother-of-pearl are mined.

Major ports: Aden, Dar es Salaam, Durban, Kannur, Colombo, Kochi, Mangalore, Muscat, Mogadishu, Mombasa, Mumbai, Port Louis, Port Elizabeth, Sihanoukville, Sofala, Tanga, Hambantota, Chennai, Yangon.

Indian Ocean States: Republic of South Africa, Mozambique, Tanzania, Kenya, Somalia, Ethiopia, Eritrea, Sudan, Egypt, Saudi Arabia, Yemen, Oman, United United Arab Emirates, Qatar, Bahrain, Kuwait, Iraq, Iran, Pakistan, India, Bangladesh, Myanmar, Thailand, Malaysia, Indonesia, East Timor, Australia, Comoros, Mauritius, Madagascar, Maldives, Reunion (France), Seychelles, Sri Lanka .

Indian Ocean is component world ocean. His maximum depth- 7729 m (Zonda Trench), and the average depth is slightly more than 3700 m, which is the second result after the depths of the Pacific Ocean. The size of the Indian Ocean is 76.174 million km2. This is 20% of the world's oceans. The volume of water is about 290 million km3 (together with all the seas).

The waters of the Indian Ocean are distinguished by their light blue color and good transparency. This is due to the fact that very few freshwater rivers flow into it, which are the main "troublemakers". By the way, due to this, the water in the Indian Ocean is much saltier compared to the salinity of other oceans.

Location of the Indian Ocean

Most of the Indian Ocean is in the Southern Hemisphere. It borders Asia to the north, Antarctica to the south, Australia to the east, and the African continent to the west. In addition, in the southeast, its waters connect with the waters of the Pacific Ocean, and in the southwest with the Atlantic Ocean.

Seas and gulfs of the Indian Ocean

The Indian Ocean does not have as many seas as other oceans. For example, compared to Atlantic Ocean they are 3 times smaller. Most of the seas are located in its northern part. In the tropical zone are: Red (the most salty sea on Earth), Laccadive, Arabian, Arafura, Timor and Andaman seas. The Antarctic zone hosts the d'Urville, Commonwealth, Davis, Riiser-Larsen, Cosmonauts seas.

The largest bays of the Indian Ocean are the Persian, Bengal, Oman, Aden, Prydz and the Great Australian.

Indian Ocean Islands

The Indian Ocean is not distinguished by an abundance of islands. The largest islands of continental origin are Madagascar, Sumatra, Sri Lanka, Java, Tasmania, Timor. Also, there are volcanic islands, such as Mauritius, Renyon, Kerguelen, and coral - Chagos, Maldives, Andaman, etc.

Underwater world of the Indian Ocean

Since more than half of the Indian Ocean is located in the tropical and subtropical zones, its underwater world is very rich and diverse in terms of species. The coastal zone in the tropics is replete with numerous colonies of crabs and unique fish - mudskippers. Corals live in shallow waters, and various algae grow in temperate waters - calcareous, brown, red.

The Indian Ocean is home to dozens of species of crustaceans, molluscs and jellyfish. A fairly large number of sea snakes also live in the ocean waters, among which there are also poisonous species.

Sharks are a special pride of the Indian Ocean. Its waters are plowed by many species of these predators, namely tiger, mako, gray, blue, great white sharks, etc.

Mammals are represented by killer whales and dolphins. Several species of pinnipeds (seals, dugongs, seals) and whales live in the southern part of the ocean.

Despite all the richness of the underwater world, seafood fishing in the Indian Ocean is rather poorly developed - only 5% of the world's catch. Sardines, tuna, shrimp, lobsters, rays and lobsters are harvested in the ocean.

1. The ancient name of the Indian Ocean is Eastern.

2. In the Indian Ocean, ships are regularly found in good condition, but without a crew. Where he disappears is a mystery. Over the past 100 years, there have been 3 such ships - Tarbon, Houston Market (tankers) and the Cabin Cruiser.

3. Many species of the underwater world of the Indian Ocean have a unique property - they can glow. This is what explains the appearance of luminous circles in the ocean.

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The Indian Ocean is the third largest ocean on Earth, covering about 20% of its water surface. Its area is 76.17 million km², volume - 282.65 million km³. The deepest point of the ocean is in the Sunda Trench (7729 m).

  • Area: 76,170 thousand km²
  • Volume: 282,650 thousand km³
  • Maximum depth: 7729 m
  • Average depth: 3711 m

In the north it washes Asia, in the west - Africa, in the east - Australia; in the south it borders on Antarctica. The border with the Atlantic Ocean runs along the 20 ° meridian of east longitude; from the Pacific - along the 146 ° 55 'meridian of eastern longitude. The northernmost point of the Indian Ocean is located at approximately 30° north latitude in the Persian Gulf. The width of the Indian Ocean is approximately 10,000 km between the southern points of Australia and Africa.

Etymology

The ancient Greeks called the western part of the ocean known to them with adjacent seas and bays the Erythrean Sea (ancient Greek Ἐρυθρά θάλασσα - Red Sea, and in old Russian sources the Red Sea). Gradually, this name began to be attributed only to the nearest sea, and the ocean gets its name from India, the country most famous at that time for its wealth on the shores of the ocean. So Alexander the Great in the IV century BC. e. calls it Indicon Pelagos (ancient Greek Ἰνδικόν πέλαγος) - "Indian Sea". Among the Arabs, it is known as Bar-el-Hind (modern Arabic المحيط الهندي‎‎ - al-mụkhіt al-hindi) - "Indian Ocean". Since the 16th century, the name Oceanus Indicus (lat. Oceanus Indicus) introduced by the Roman scientist Pliny the Elder back in the 1st century was established - the Indian Ocean.

Physical and geographical characteristics

General information

The Indian Ocean is mainly located south of the Tropic of Cancer between Eurasia to the north, Africa to the west, Australia to the east and Antarctica to the south. The border with the Atlantic Ocean runs along the meridian of Cape Agulhas (20 ° E to the coast of Antarctica (Queen Maud Land)). The border with the Pacific Ocean runs: south of Australia - along the eastern border of the Bass Strait to the island of Tasmania, then along the meridian 146 ° 55 'E. to Antarctica; north of australia- between the Andaman Sea and the Strait of Malacca, further along the southwestern coast of the island of Sumatra, the Sunda Strait, the southern coast of the island of Java, the southern borders of the Bali and Savu seas, the northern border of the Arafura Sea, the southwestern coast of New Guinea and the western border of the Torres Strait. Sometimes the southern part of the ocean, with northern border from 35°S sh. (on the basis of the circulation of water and the atmosphere) up to 60 ° S. sh. (according to the nature of the bottom topography), they are attributed to the Southern Ocean, which is not officially distinguished.

Seas, bays, islands

The area of ​​the seas, bays and straits of the Indian Ocean is 11.68 million km² (15% of the total ocean area), the volume is 26.84 million km³ (9.5%). The seas and main bays located along the coast of the ocean (clockwise): Red Sea, Arabian Sea (Gulf of Aden, Gulf of Oman, Persian Gulf), Laccadive Sea, Bay of Bengal, Andaman Sea, Timor Sea, Arafura Sea (Gulf of Carpentaria), Large Australian Gulf, Mawson Sea, Davis Sea, Commonwealth Sea, Astronaut Sea (the last four are sometimes referred to as the Southern Ocean).

Some islands - for example, Madagascar, Socotra, Maldives - are fragments of ancient continents, others - Andaman, Nicobar or Christmas Island - are of volcanic origin. The largest island in the Indian Ocean is Madagascar (590 thousand km²). The largest islands and archipelagos: Tasmania, Sri Lanka, the Kerguelen archipelago, Andaman Islands, Melville, Mascarene Islands (Reunion, Mauritius), Kangaroo, Nias, Mentawai Islands (Siberut), Socotra, Groot Island, Comoros, Tiwi Islands (Bathurst), Zanzibar, Simeulue, Furno Islands (Flinders), Nicobar Islands, Qeshm , King, Bahrain Islands, Seychelles, Maldives, Chagos Archipelago.

The history of the formation of the Indian Ocean

During the early Jurassic, the ancient supercontinent Gondwana began to break apart. As a result, Africa with Arabia, Hindustan and Antarctica with Australia were formed. The process ended at the turn of the Jurassic and Cretaceous periods (140-130 million years ago), and a young basin of the modern Indian Ocean began to form. In the Cretaceous period, the ocean floor grew due to the movement of Hindustan to the north and the reduction in the area of ​​the Pacific and Tethys oceans. In the Late Cretaceous, the split of the single Australo-Antarctic continent began. At the same time, as a result of the formation of a new rift zone, the Arabian plate broke away from the African plate, and the Red Sea and the Gulf of Aden were formed. At the beginning of the Cenozoic era, the growth of the Indian Ocean stopped towards the Pacific, but continued towards the Tethys Sea. At the end of the Eocene - the beginning of the Oligocene, Hindustan collided with the Asian continent.

Today, the movement of tectonic plates continues. The axis of this movement is the mid-ocean rift zones of the African-Antarctic Ridge, the Central Indian Ridge, and the Australo-Antarctic Rise. The Australian plate continues to move north at a rate of 5-7 cm per year. The Indian plate continues to move in the same direction at a speed of 3-6 cm per year. The Arabian Plate is moving northeast at a rate of 1-3 cm per year. The Somali Plate continues to break away from the African Plate along the East African Rift Zone, which is moving at a speed of 1-2 cm per year in northeast direction. December 26, 2004 in the Indian Ocean near the island of Simeulue, located off the northwestern coast of the island of Sumatra (Indonesia), there was the largest earthquake in the history of observations with a magnitude of up to 9.3. The reason was a shift of about 1200 km (according to some estimates - 1600 km) of the earth's crust at a distance of 15 m along the subduction zone, as a result of which the Hindustan plate moved under the Burma plate. The earthquake caused a tsunami, which brought enormous destruction and a huge number of deaths (up to 300 thousand people).

Geological structure and topography of the bottom of the Indian Ocean

mid-ocean ridges

Mid-ocean ridges divide the bottom of the Indian Ocean into three sectors: African, Indo-Australian and Antarctic. There are four mid-ocean ridges: the West Indian, Arabian-Indian, Central Indian ridges and the Australo-Antarctic Rise. The West Indian Ridge is located in the southwestern part of the ocean. It is characterized by underwater volcanism, seismicity, rift-type crust and rift structure of the axial zone; it is crossed by several oceanic faults of submeridional strike. In the region of the island of Rodrigues (Mascarene archipelago), there is a so-called triple connection, where the system of ridges is divided to the north into the Arabian-Indian ridge and to the south-west into the Central Indian ridge. The Arabian-Indian ridge is composed of ultramafic rocks; deep depressions(ocean troughs) with depths up to 6.4 km. The northern part of the ridge is crossed by the most powerful Owen Fault, along which the northern segment of the ridge experienced a displacement of 250 km to the north. Further west, the rift zone continues into the Gulf of Aden and north-northwest into the Red Sea. Here the rift zone is composed of carbonate deposits with volcanic ash. In the rift zone of the Red Sea, strata of evaporites and metal-bearing silts associated with powerful hot (up to 70 °C) and very saline (up to 350 ‰) juvenile waters have been found.

In the southwest direction from the triple junction extends the Central Indian Range, which has a well-defined rift and flank zones, ending in the south with the Amsterdam volcanic plateau with the volcanic islands of Saint-Paul and Amsterdam. From this plateau, the Australo-Antarctic Rise extends to the east-southeast, having the form of a wide, slightly dissected arch. In the eastern part, the uplift is dissected by a series of meridional faults into a number of segments displaced relative to each other in the meridional direction.

African segment of the ocean

The underwater margin of Africa has a narrow shelf and a distinct continental slope with marginal plateaus and continental foot. In the south, the African continent forms protrusions pushed to the south: the Agulhas bank, the Mozambique and Madagascar ridges, composed of continental-type earth's crust. The mainland foot forms a sloping plain extending south along the coast of Somalia and Kenya, which continues in the Mozambique Channel and borders Madagascar from the east. The Mascarene Range runs along the east of the sector, in the northern part of which the Seychelles are located.

The surface of the ocean floor in the sector, especially along the mid-ocean ridges, is dissected by numerous ridges and troughs associated with submeridional fault zones. There are many underwater volcanic mountains, most of which are built on coral superstructures in the form of atolls and underwater coral reefs. Between the mountain rises are the basins of the ocean bed with hilly and mountainous terrain: Agulhas, Mozambique, Madagascar, Mascarene and Somali. In the Somali and Mascarene basins, vast flat abyssal plains are formed, where a significant amount of terrigenous and biogenic sedimentary material enters. In the Mozambique Basin, there is an underwater valley of the Zambezi River with a system of alluvial fans.

Indo-Australian segment of the ocean

The Indo-Australian segment occupies half the area of ​​the Indian Ocean. In the west, in the meridional direction, the Maldives Range passes, on the top surface of which the islands of Laccadive, Maldives and Chagos are located. The ridge is composed of continental-type crust. A very narrow shelf, a narrow and steep continental slope, and a very wide continental foot stretched along the coast of Arabia and Hindustan, mainly formed by two giant fans of turbid streams of the Indus and Ganges rivers. These two rivers carry 400 million tons of debris into the ocean. The Indus cone extends far into the Arabian Basin. And only the southern part of this basin is occupied by a flat asbyssal plain with separate seamounts.

Almost exactly 90° E. The blocky oceanic East Indian Ridge stretches for 4,000 km from north to south. Between the Maldives and the East Indian Ranges is the Central Basin - the largest basin of the Indian Ocean. Its northern part is occupied by the Bengal alluvial fan (from the Ganges River), to the southern border of which the abyssal plain adjoins. In the central part of the basin there is a small Lanka ridge and the Afanasy Nikitin seamount. To the east of the East Indian Ridge are the Cocos and Western Australian Basins, separated by a blocky sublatitudinally oriented Cocos Rise with the Cocos and Christmas Islands. In the northern part of the Coconut Basin there is a flat abyssal plain. From the south, it is bounded by the West Australian Rise, which drops steeply to the south and gently plunges under the bottom of the basin to the north. From the south, the West Australian Rise is bounded by a steep ledge associated with the Diamantina Fault Zone. The ralome zone combines deep and narrow grabens (the most significant are the Ob and Diamatina) and numerous narrow horsts.

The transitional region of the Indian Ocean is represented by the Andaman Trench and the deep-water Sunda Trench, which is associated with the maximum depth of the Indian Ocean (7209 m). The outer ridge of the Sunda island arc is the underwater Mentawai Range and its continuation in the form of the Andaman and Nicobar Islands.

Underwater margin of the Australian mainland

The northern part of the Australian continent is bordered by a wide Sahul shelf with many coral structures. To the south, this shelf narrows and widens again off the coast. south australia. The continental slope is composed of marginal plateaus (the largest of them are the Exmouth and Naturalists plateaus). In the western part of the Western Australian Basin, the Zenith, Cuvier and other rises are located, which are pieces of the continental structure. Between the southern underwater margin of Australia and the Australo-Antarctic Rise, there is a small South Australian Basin, which is a flat abyssal plain.

Antarctic segment of the ocean

The Antarctic segment is bounded by the West Indian and Central Indian ridges, and from the south by the coast of Antarctica. Under the influence of tectonic and glaciological factors, the shelf of Antarctica is overdeepened. A wide continental slope is cut by large and wide canyons, through which supercooled water flows from the shelf into the abyssal depressions. The continental foot of Antarctica is distinguished by a wide and significant (up to 1.5 km) thickness of loose deposits.

The largest protrusion of the Antarctic continent is the Kerguelen Plateau, as well as the volcanic uplift of the Prince Edward and Crozet Islands, which divide the Antarctic sector into three basins. To the west is the African-Antarctic Basin, which is half located in the Atlantic Ocean. Most of its bottom is a flat abyssal plain. The Crozet Basin, located to the north, is characterized by a large-hilly bottom topography. The Australo-Antarctic Basin, lying to the east of Kerguelen, is occupied in the southern part by a flat plain, and in the northern part by Abyssotian hills.

Bottom sediments

The Indian Ocean is dominated by calcareous foraminiferal-coccolithic deposits, which occupy more than half of the bottom area. The wide development of biogenic (including coral) calcareous deposits is explained by the position of a large part of the Indian Ocean within the tropical and equatorial belts, as well as by the relatively shallow depth of oceanic basins. Numerous mountain uplifts are also favorable for the formation of lime deposits. In the deep parts of some basins (for example, the Central, Western Australian), deep-sea red clays occur. The equatorial belt is characterized by radiolarian muds. In the southern cold part of the ocean, where the conditions for the development of diatom flora are especially favorable, siliceous diatom deposits are represented. Iceberg sediments are deposited off the Antarctic coast. At the bottom of the Indian Ocean, ferromanganese nodules are widely distributed, confined mainly to areas of deposition of red clays and radiolarian oozes.

Climate

IN this region four climatic zones are distinguished, stretched along the parallels. Under the influence of the Asian continent, a monsoonal climate is established in the northern part of the Indian Ocean with frequent cyclones moving towards the coasts. High atmospheric pressure over Asia in winter causes the northeast monsoon to form. In summer, it is replaced by a humid southwest monsoon, carrying air from the southern regions of the ocean. During the summer monsoon, there is often a wind force of more than 7 points (with a frequency of 40%). In summer, the temperature over the ocean is 28-32 °C, in winter it drops to 18-22 °C.

In the southern tropics, the southeast trade wind dominates, which in winter does not extend north of 10°N. The average annual temperature reaches 25 °C. In the zone 40-45°S. Throughout the year, the western transfer of air masses is characteristic, it is especially strong in temperate latitudes, where the frequency of storm weather is 30-40%. In the mid-ocean, stormy weather is associated with tropical hurricanes. In winter, they can also occur in the southern tropical zone. Most often, hurricanes occur in the western part of the ocean (up to 8 times a year), in the regions of Madagascar and Mascarene Islands. In subtropical and temperate latitudes, the temperature reaches 10-22 °C in summer and 6-17 °C in winter. From 45 degrees and south are characteristic strong winds. In winter, the temperature here ranges from -16 °C to 6 °C, and in summer - from -4 °C to 10 °C.

The maximum amount of precipitation (2.5 thousand mm) is confined to the eastern region of the equatorial zone. There is also increased cloudiness (more than 5 points). The least amount of precipitation is observed in the tropical regions of the southern hemisphere, especially in the eastern part. In the northern hemisphere, clear weather is characteristic of the Arabian Sea for most of the year. The maximum cloudiness is observed in Antarctic waters.

Hydrological regime of the Indian Ocean

Surface water circulation

In the northern part of the ocean, there is a seasonal change in currents caused by monsoon circulation. In winter, the Southwest Monsoon Current sets in, starting in the Bay of Bengal. South of 10° N. sh. this current passes into the Western Current, crossing the ocean from the Nicobar Islands to the coast of East Africa. Further, it branches: one branch goes north to the Red Sea, the other - south to 10 ° S. sh. and, turning to the east, gives rise to the Equatorial countercurrent. The latter crosses the ocean and, off the coast of Sumatra, is again divided into a part that goes into the Andaman Sea and the main branch, which between the Lesser Sunda Islands and Australia goes to the Pacific Ocean. In summer, the southeast monsoon ensures the movement of the entire mass of surface water to the east, and the Equatorial countercurrent disappears. The summer monsoon current begins off the coast of Africa with the powerful Somali current, which is joined by the current from the Red Sea in the Gulf of Aden. In the Bay of Bengal, the summer monsoon current divides into north and south, which flows into the South Equatorial Current.

In the southern hemisphere, currents are constant, without seasonal fluctuations. Driven by the trade winds, the South Trade Wind Current crosses the ocean from east to west towards Madagascar. It intensifies in winter (for the southern hemisphere) due to additional feeding by the waters of the Pacific Ocean coming along the northern coast of Australia. At Madagascar, the South Equatorial Current forks, giving rise to the Equatorial Countercurrent, Mozambique and Madagascar currents. Merging southwest of Madagascar, they form the warm Agulhas current. The southern part of this current goes into the Atlantic Ocean, and part of it flows into the westerly winds. On the approach to Australia, the cold West Australian Current departs from the latter to the north. Local gyres operate in the Arabian Sea, the Bengal and Great Australian Bays, and in Antarctic waters.

The northern part of the Indian Ocean is characterized by the predominance of a semidiurnal tide. The amplitudes of the tide in the open ocean are small and average 1 m. In the Antarctic and subantarctic zones, the amplitude of the tides decreases from east to west from 1.6 m to 0.5 m, and near the coast they increase to 2-4 m. The maximum amplitudes are noted between islands, in shallow bays. In the Bay of Bengal, the tide is 4.2-5.2 m, near Mumbai - 5.7 m, near Yangon - 7 m, near northwestern Australia - 6 m, and in the port of Darwin - 8 m. In other areas, the amplitude of the tides about 1-3 m.

temperature, salinity

In the equatorial zone of the Indian Ocean, the surface water temperature is about 28 ° C all year round in both the western and eastern parts of the ocean. In the Red and Arabian Seas, winter temperatures drop to 20-25 °C, but in summer the maximum temperatures for the entire Indian Ocean are set in the Red Sea - up to 30-31 °C. High winter water temperatures (up to 29 ° C) are typical for the coasts of northwestern Australia. In the southern hemisphere, at the same latitudes in the eastern part of the ocean, the water temperature in winter and summer is 1-2° lower than in the western part. Water temperatures below 0°C in summer are found south of 60°S. sh. Ice formation in these areas begins in April and the thickness of the fast ice reaches 1-1.5 m by the end of winter. Melting begins in December-January, and by March the waters are completely cleared of fast ice. In the southern part of the Indian Ocean, icebergs are common, sometimes setting north of 40 ° S. sh.

The maximum salinity of surface waters is observed in the Persian Gulf and the Red Sea, where it reaches 40-41 ‰. High salinity (more than 36 ‰) is also observed in the southern tropical zone, especially in the eastern regions, and in the northern hemisphere also in the Arabian Sea. In the neighboring Bay of Bengal, due to the desalination effect of the Ganges runoff from the Brahmaputra and the Irrawaddy, the salinity is reduced to 30-34 ‰. Increased salinity correlates with areas of maximum evaporation and the least amount of precipitation. Reduced salinity (less than 34 ‰) is characteristic of subarctic waters, where the strong freshening effect of melted glacial waters is felt. The seasonal difference in salinity is significant only in the Antarctic and equatorial zones. In winter, desalinated waters from the northeastern part of the ocean are carried by the monsoon current, forming a tongue of low salinity along 5°N. sh. In summer, this language disappears. In the Arctic waters in winter, salinity slightly increases due to the salinization of waters in the process of ice formation. Salinity decreases from the surface to the bottom of the ocean. Bottom waters from the equator to the arctic latitudes have a salinity of 34.7-34.8 ‰.

water masses

The waters of the Indian Ocean are divided into several water masses. In the part of the ocean north of 40 ° S. sh. they distinguish central and equatorial surface and subsurface water masses and underlying them (deeper than 1000 m) deep. To the north to 15-20 ° S. sh. the central water mass spreads. The temperature varies with depth from 20-25 °C to 7-8 °C, salinity is 34.6-35.5 ‰. Surface layers north of 10-15°S sh. make up the equatorial water mass with a temperature of 4-18 ° C and a salinity of 34.9-35.3 ‰. This water mass is characterized by significant speeds of horizontal and vertical movement. In the southern part of the ocean, subantarctic (temperature 5-15 ° C, salinity up to 34 ‰) and Antarctic (temperature from 0 to -1 ° C, salinity due to melting ice drops to 32 ‰) are distinguished. Deep water masses are divided into: very cold circulation, formed by lowering the Arctic water masses and the inflow of circulation water from the Atlantic Ocean; South Indian, formed as a result of lowering subarctic surface waters; North Indian, formed by dense waters flowing from the Red Sea and the Gulf of Oman. Deeper than 3.5-4 thousand m, bottom water masses are common, formed from Antarctic supercooled and dense salt water Red Sea and Persian Gulf.

Flora and fauna

The flora and fauna of the Indian Ocean is extremely diverse. The tropical region stands out for its abundance of plankton. The single-celled alga Trichodesmium (cyanobacteria) is especially abundant, due to which the surface layer of water becomes very cloudy and changes its color. The plankton of the Indian Ocean is distinguished by a large number of night-luminous organisms: peridine, some species of jellyfish, ctenophores, and tunicates. Brightly colored siphonophores, including poisonous physalia, are abundant. In temperate and arctic waters, the main representatives of plankton are copepods, euphausids and diatoms. The most numerous fish of the Indian Ocean are dolphins, tuna, notothenia and various sharks. From reptiles there are several species of giant sea turtles, sea snakes, from mammals - cetaceans (toothless and blue whales, sperm whales, dolphins), seals, sea elephants. Most cetaceans live in temperate and polar regions, where, due to the intensive mixing of waters, favorable conditions arise for the development of planktonic organisms. Birds are represented by albatrosses and frigatebirds, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and islands in the temperate ocean.

The flora of the Indian Ocean is represented by brown algae (Sargasso, Turbinarium) and green algae (Caulerpa). The calcareous algae lithotamnia and chalimeda also flourish and participate together with corals in the construction of reef structures. In the process of activity of reef-forming organisms, coral platforms are created, sometimes reaching a width of several kilometers. Typical for the coastal zone of the Indian Ocean is a phytocenosis formed by mangroves. Such thickets are especially characteristic of river mouths and occupy significant areas in Southeast Africa, in western Madagascar, in South-East Asia and other areas. For temperate and Antarctic waters, the most characteristic are red and brown algae, mainly from the groups of fucus and kelp, porphyry, and helidium. In the subpolar regions of the southern hemisphere, giant macrocystis are found.

Zoobenthos is represented by a variety of mollusks, calcareous and flint sponges, echinoderms (sea urchins, starfish, brittle stars, holothurians), numerous crustaceans, hydroids, and bryozoans. Coral polyps are widespread in the tropical zone.

Ecological problems

Human economic activity in the Indian Ocean has led to the pollution of its waters and to the reduction of biodiversity. At the beginning of the 20th century, some species of whales were almost completely exterminated, others - sperm whales and sei whales - still survived, but their number was greatly reduced. Since the 1985-1986 season, the International Whaling Commission has introduced a complete moratorium on commercial whaling of any kind. In June 2010, at the 62nd meeting of the International Whaling Commission, under pressure from Japan, Iceland and Denmark, the moratorium was suspended. The Mauritius dodo, destroyed by 1651 on the island of Mauritius, became a symbol of extinction and extinction of species. After it became extinct, people first formed the opinion that they could cause the extinction of other animals.

A great danger in the ocean is the pollution of waters with oil and oil products (the main pollutants), some heavy metals, and waste from the nuclear industry. The routes of oil tankers transporting oil from the countries of the Persian Gulf run across the ocean. Any major accident can lead to an ecological catastrophe and the death of many animals, birds and plants.

States of the Indian Ocean

States along the borders of the Indian Ocean (clockwise):

  • Republic Of South Africa,
  • Mozambique,
  • Tanzania,
  • Kenya,
  • Somalia,
  • Djibouti,
  • Eritrea,
  • Sudan,
  • Egypt,
  • Israel,
  • Jordan,
  • Saudi Arabia,
  • Yemen,
  • Oman,
  • United Arab Emirates,
  • Qatar,
  • Kuwait,
  • Iraq,
  • Iran,
  • Pakistan,
  • India,
  • Bangladesh,
  • Myanmar,
  • Thailand,
  • Malaysia,
  • Indonesia,
  • East Timor,
  • Australia.

In the Indian Ocean there are island states and possessions of states outside the region:

  • Bahrain,
  • British Indian Ocean Territory (UK),
  • Comoros,
  • Mauritius,
  • Madagascar,
  • Mayotte (France),
  • Maldives,
  • Reunion (France),
  • Seychelles,
  • French Southern and Antarctic Territories (France),
  • Sri Lanka.

Research history

The shores of the Indian Ocean - one of the areas of settlement ancient peoples and the emergence of the first river civilizations. In ancient times, ships such as junks and catamarans were used by people for sailing, with favorable monsoons from India to East Africa and back. The Egyptians in 3500 BC conducted a brisk maritime trade with the countries of the Arabian Peninsula, India and East Africa. The countries of Mesopotamia for 3000 years BC made sea trips to Arabia and India. From the 6th century BC, the Phoenicians, according to the Greek historian Herodotus, made sea voyages from the Red Sea across the Indian Ocean to India and around Africa. IN VI-V centuries BC, Persian merchants conducted maritime trade from the mouth of the Indus River along the east coast of Africa. At the end of the Indian campaign of Alexander the Great in 325 BC, the Greeks with a huge fleet with a crew of five thousand in severe storm conditions made a many-month voyage between the mouths of the Indus and Euphrates rivers. Byzantine merchants in the 4th-6th centuries penetrated in the east to India, and in the south - to Ethiopia and Arabia. Since the 7th century Arab sailors began intensive exploration of the Indian Ocean. They perfectly studied the coast of East Africa, West and East India, the islands of Socotra, Java and Ceylon, visited the Laccadives and Maldives, the islands of Sulawesi, Timor and others.

At the end of the 13th century, the Venetian traveler Marco Polo, on his way back from China, passed through the Indian Ocean from Malacca to the Strait of Hormuz, visiting Sumatra, India, and Ceylon. The journey was described in the Book of the Diversity of the World, which had a significant impact on navigators, cartographers, and writers of the Middle Ages in Europe. Chinese junks made trips along the Asian shores of the Indian Ocean and reached the Eastern coast of Africa (for example, Zheng He's seven voyages in 1405-1433). An expedition led by the Portuguese navigator Vasco da Gama, rounding Africa from the south, passing along east coast continent in 1498, reached India. In 1642, the Dutch trading East India Company organized an expedition of two ships under the command of Captain Tasman. As a result of this expedition, central part Indian Ocean and it was proved that Australia is a mainland. In 1772, a British expedition under the command of James Cook penetrated the southern Indian Ocean to 71°S. sh., while extensive scientific material on hydrometeorology and oceanography was obtained.

From 1872 to 1876, the first scientific ocean expedition took place on the English sailing-steam corvette Challenger, new data were obtained on the composition of the ocean waters, on the flora and fauna, on the bottom topography and soils, the first map of the depths of the ocean was compiled and the first collection was collected. deep sea animals. World expedition conducted a large research work in the Indian Ocean. A great contribution to the study of the Indian Ocean was made by oceanographic expeditions on the German ships Valkyrie (1898-1899) and Gauss (1901-1903), on the English ship Discovery II (1930-1951), the Soviet expeditionary ship Ob ( 1956-1958) and others. In 1960-1965, under the auspices of the Intergovernmental Oceanographic Expedition under UNESCO, an international Indian Ocean Expedition was carried out. She was the largest of all the expeditions ever to work in the Indian Ocean. The program of oceanographic work covered almost the entire ocean with observations, which was facilitated by the participation of scientists from about 20 countries in the research. Among them: Soviet and foreign scientists on the research ships Vityaz, A. I. Voeikov”, “Yu. M. Shokalsky, non-magnetic schooner Zarya (USSR), Natal (South Africa), Diamantina (Australia), Kistna and Varuna (India), Zulfikvar (Pakistan). As a result, valuable new data were collected on hydrology, hydrochemistry, meteorology, geology, geophysics and biology of the Indian Ocean. Since 1972, regular deep-sea drilling has been carried out on the American vessel Glomar Challenger, work to study the movement of water masses on great depths ah, biological research.

In recent decades, numerous measurements of the ocean have been carried out using space satellites. The result was released in 1994 by the American National Center geophysical data bathymetric atlas of the oceans with a map resolution of 3-4 km and a depth accuracy of ±100 m.

Economic importance

Fishing and marine industries

The importance of the Indian Ocean for the world fishing industry is small: the catches here are only 5% of the total. The main commercial fish of the local waters are tuna, sardine, anchovy, several species of sharks, barracudas and rays; Shrimps, lobsters and lobsters are also caught here. Until recently, whaling, which was intensive in the southern regions of the ocean, is rapidly curtailing due to the almost complete extermination of some species of whales. On the northwestern coast of Australia, in Sri Lanka and the Bahrain Islands, pearls and mother-of-pearl are mined.

Transport routes

The most important transport routes of the Indian Ocean are routes from the Persian Gulf to Europe, North America, Japan and China, as well as from the Gulf of Aden to India, Indonesia, Australia, Japan and China. Main navigable straits Indian Strait: Mozambique, Bab-el-Mandeb, Hormuz, Sunda. The Indian Ocean is connected by the artificial Suez Canal to mediterranean sea Atlantic Ocean. In the Suez Canal and the Red Sea, all the main cargo flows of the Indian Ocean converge and diverge. Major ports: Durban, Maputo (export: ore, coal, cotton, minerals, oil, asbestos, tea, raw sugar, cashew nuts, import: machinery and equipment, manufactured goods, food), Dar es Salaam (export : cotton, coffee, sisal, diamonds, gold, oil products, cashew nuts, cloves, tea, meat, leather, import: manufactured goods, food, chemicals), Jeddah, Salalah, Dubai, Bandar Abbas, Basra (export: oil, grain, salt, dates, cotton, leather, import: cars, timber, textiles, sugar, tea), Karachi (export: cotton, fabrics, wool, leather, shoes, carpets, rice, fish, import: coal, coke, oil products , mineral fertilizers, equipment, metals, grain, food, paper, jute, tea, sugar), Mumbai (export: manganese and iron ores, oil products, sugar, wool, leather, cotton, fabrics, import: oil, coal, cast iron, equipment, grain, chemicals, manufactured goods), Colombo, Chennai (iron ore, coal, granite, fertilizers, petroleum products, containers, vehicles), Kolkata (export: coal, iron and copper ores, tea, imports: manufactured goods, grain, foodstuffs, equipment), Chittagong (clothing, jute, leather, tea, chemicals), Yangon (exports: rice, hardwood, non-ferrous metals, bagasse, legumes, rubber, gems, import: coal, cars, food, fabrics), Perth Fremantle (export: ores, alumina, coal, coke, caustic soda, phosphate raw materials, import: oil, equipment).

Minerals

The most important minerals of the Indian Ocean are oil and natural gas. Their deposits are found on the shelves of the Persian and Suez Gulfs, in the Bass Strait, on the shelf of the Hindustan Peninsula. On the coasts of India, Mozambique, Tanzania, South Africa, the islands of Madagascar and Sri Lanka, ilmenite, monazite, rutile, titanite and zirconium are exploited. Off the coast of India and Australia there are deposits of barite and phosphorite, and in the shelf zones of Indonesia, Thailand and Malaysia, deposits of cassiterite and ilmenite are exploited on an industrial scale.

Recreational resources

The main recreational areas of the Indian Ocean: the Red Sea, the western coast of Thailand, the islands of Malaysia and Indonesia, the island of Sri Lanka, the area of ​​coastal urban agglomerations of India, the eastern coast of Madagascar, the Seychelles and Maldives. Among the countries of the Indian Ocean with the largest flow of tourists (according to 2010 data from the World Tourism Organization) stand out: Malaysia (25 million visits per year), Thailand (16 million), Egypt (14 million), Saudi Arabia (11 million), South Africa (8 million), United Arab Emirates (7 million), Indonesia (7 million), Australia (6 million), India (6 million), Qatar (1.6 million), Oman (1.5 million).

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The Indian Ocean is smaller in area than the Pacific. Its water area occupies 76 million square kilometers. It is located almost entirely in the southern hemisphere. In ancient times, people considered it a great sea.

The largest islands of the Indian Ocean are Sri Lanka, Madagascar, Masirai, Kuria Muria, Socotra, Greater Sunda, Seychelles, Nicobar, Andanam, Coconut, Amirant, Chagos, Maldives, Laccadive.

The coast of the Indian Ocean - the places where ancient civilizations were located. Scientists believe that navigation in this ocean began earlier than in others, about 6 thousand years ago. The first to describe ocean routes were the Arabs. The accumulation of navigational information about the Indian Ocean began as early as the travels of Vasco de Gama (1497-1499). At the end of the 18th century, the first measurements of its depths were made by English navigator James Cook.

A detailed study of the ocean began at the end of the 19th century. The most extensive study was carried out by the British research team on board the Challenger. At the moment, dozens of research expeditions from different states study the nature of the ocean, revealing its wealth.

The average depth of the Indian Ocean is about 3,700 meters, and the maximum is 7,700 meters. Seamounts are located in the western part of the ocean, connecting in a place located south of the cape Good Hope, with the Mid-Atlantic Ridge. Near the center of the ridge in the Indian Ocean are deep faults, areas of seismic activity and volcanic eruptions on the ocean floor. These faults stretch to the Red Sea and come out on land. The bottom of the ocean is crossed by numerous hills.

If the Pacific Ocean inspires with its blue color, then the Indian Ocean is known for the transparency of its dark blue and azure waters. This is due to the purity of the ocean, since little fresh water enters the ocean from rivers - "disturbers of purity", especially in its southern part.

The Indian Ocean is saltier than other oceans. This is especially noticeable in the northwestern part of the ocean, where hot air masses from the Sahara are added to high water temperatures. The record holder for salt content is the Red Sea (up to 42%) and the Persian Gulf.

The northern part of the Indian Ocean is heavily influenced by land; it rightfully deserves the name "monsoon sea". In winter, dry air comes from the largest continent - Eurasia. In summer, the situation changes dramatically. The heated ocean saturates the air big amount moisture. Then, moving to the mainland, it breaks out over the south of the continent with heavy rains. Before the summer monsoon winds, thunderstorms pass, generating sea swell, carried by the wind to the southwestern coast of India. In autumn and spring, typhoons form in the northern part of the Indian Ocean, bringing many problems to the inhabitants of the shores of the Arabian Sea and the Bay of Bengal, as well as to sailors. In the south of the Indian Ocean, you can feel the cold breath of Antarctica, in these places the ocean is the most severe.

Indian Ocean forms good conditions for coral life. Their large colonies are found in the Maldives, located south of the peninsula Hindustan. These islands are by composition the longest coral islands in the world.

The Indian Ocean is rich in its fish resources, which have been used by man since ancient times. For many residents of the coast, fishing is the only source of income.

Since time immemorial, pearls have been mined in these places. The coast of the island of Sri Lanka since ancient times served as a place for the extraction of emeralds, diamonds, emeralds and many other types of precious stones.

Under the bottom of the Persian Gulf, located in the northwestern part of the Indian Ocean, gas and oil reserves have been formed for thousands of years.


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 Indian Ocean and its structure

.Minerals

.Climate of the Indian Ocean

.vegetable and animal world

.Fishing and marine industry


Introduction

Indian Ocean- the youngest and warmest among the world's oceans. Most of it is in the southern hemisphere, and in the north it goes far into the mainland, which is why ancient people considered it just a big sea. It was here, in the Indian Ocean, that man began his first sea voyages.

The largest rivers of Asia belong to the Indian Ocean basin: the Salween, the Irrawaddy and the Ganges with the Brahmaputra, which flow into the Bay of Bengal; the Indus, which flows into the Arabian Sea; Tigris and Euphrates, merging a little above the confluence with the Persian Gulf. From major rivers Africa, also flowing into the Indian Ocean, should be called Zambezi and Limpopo. Because of them, the water off the coast of the ocean is muddy, with a high content of sedimentary rocks - sand, silt and clay. But open waters the oceans are amazingly clear. The tropical islands of the Indian Ocean are famous for their cleanliness. A variety of animals have found their place on coral reefs. The Indian Ocean is home to the famous sea devils, rare whale sharks, bigmouths, 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 - Australia from Antarctica (in the Paleogene, about 50 million years ago).

The Indian Ocean and its shores remain poorly explored. The name of the Indian Ocean is found already at the beginning of the 16th century. 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 by the sea of ​​India, some (Varenius) by the Australian Ocean, and Fleurie recommended (in the 18th century) to call it even the Great Indian Gulf, considering it as part of the Pacific Ocean.

In ancient times (3000-1000 BC), sailors from India, Egypt and Phoenicia traveled across the northern part of the Indian Ocean. The first navigation charts were compiled by the ancient Arabs. At the end of the 15th century, the first European, the famous Portuguese Vasco da Gama, circled 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 British) increasingly appeared in the Indian Ocean basin, and by the middle of the 19th century, most of its coasts and islands were already the property of Great Britain.

Discovery historycan 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 navigators, who, in 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 south to 71 ° S. sh.

The second period was marked by the beginning of deep-sea research, first conducted by Cook in 1772 and continued by Russian and foreign expeditions. The main Russian expeditions were - O. Kotzebue on the "Rurik" (1818) and Pallen 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 work was 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 conducted 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 of the Earth (after the Pacific and Atlantic), covering about 20% of its water surface. Almost all of it is 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 Arabian Peninsula and Africa, in the east - Indochina, the Sunda Islands and Australia, in the south - the Southern Ocean. The border between the Indian and Atlantic Oceans runs along the 20° meridian of east longitude. (Meridian of the Cape of Needles), between the Indian and Pacific Oceans runs along the 147 ° meridian of east longitude (meridian southern cape islands of Tasmania). The northernmost point of the Indian Ocean is located at approximately 30° north latitude in the Persian Gulf. The width of the Indian Ocean is approximately 10,000 km 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 fewest seas compared to other oceans. The largest seas are located in the northern part: 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, there are the island states of Madagascar (the fourth largest island in the world), Sri Lanka, the Maldives, Mauritius, the Comoros, and the Seychelles. The ocean washes in the east such states: 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 on 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 - Maldives, Laccadive, Chagos, Cocos, most of the Andaman, etc.


. Bottom relief


The ocean floor is a system of mid-ocean ridges and basins. In the region of Rodrigues Island (Mascarene Archipelago) there is a so-called triple junction, where the Central Indian and West Indian ridges converge, as well as the Australo-Antarctic Rise. The ridges consist of steep mountain ranges, cut by normal or oblique faults with respect to the axes of the chains, and divide the basalt ocean floor into 3 segments, and their tops are, as a rule, extinct volcanoes. The bottom of the Indian Ocean is covered with deposits of the Cretaceous and later periods, the thickness of which varies from several hundred meters to 2-3 km. The deepest of the numerous trenches of the ocean is the Yavan (4,500 km long and 29 km wide). The rivers flowing into the Indian Ocean carry with them huge amounts of sedimentary material, especially from the territory of India, creating high alluvial rapids.

The coast of the Indian Ocean is replete with cliffs, deltas, atolls, coastal coral reefs and salt marshes overgrown with mangroves. Some islands - for example, Madagascar, Socotra, 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 crowned with coral structures. Andaman, Nicobar or Christmas Island - are of volcanic origin. The Kerguelen Plateau, located in the southern part of the ocean, also has a volcanic origin.

An underwater earthquake in the Indian Ocean on December 26, 2004 triggered a tsunami that has been recognized as the deadliest natural disaster in 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 located in the Indian Ocean, north of the island of Simeulue, located near 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 massive destruction and a huge number of dead people, even in Port Elizabeth, in South Africa, 6900 km from the epicenter. Died, according to various estimates, from 225 thousand to 300 thousand people. The true death toll is unlikely to ever be known, as many people were swept into the sea by the water.

With regard to 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 coasts, brown in volcanic areas, but lighter and sometimes pinkish or yellowish near coral coasts due to the lime prevailing here. Globigerin silt, consisting of microscopic foraminifers, covers the deeper parts of the ocean floor almost to a depth of 4500 m; south of parallel 50°S sh. calcareous foraminiferal deposits disappear and are replaced by microscopic siliceous, from the group of algae, diatoms. With regard to the accumulation of diatom remains on the bottom, the southern part of the Indian Ocean is especially different from other oceans, where diatoms are found only in places. Red clay occurs at depths greater than 4500 m; it has the color red, or brown, or chocolate.

indian ocean climate fossil fishery

4. Characteristics of waters


Surface water circulationin the northern part of the Indian Ocean has a monsoonal character: in summer - northeast and east current, in winter - southwestern and western current. During the winter months between 3° and 8° S. sh. an inter-trade (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the South Trade Wind in the North, Madagascar and Needle in the West and cold ones - the West Winds in the South and West Australian in the East South of 55 ° S. sh. several weak cyclonic water cycles develop, closing off the coast of Antarctica with an easterly current.

Belt of the Indian Oceanbetween 10 ° With. sh. and 10 ° Yu. sh. called the thermal equator, where the surface water temperature is 28-29°C. To the south of this zone, the temperature drops, reaching ?1°C off the coast of Antarctica. In January and February, the ice along the coast of this mainland melts, huge ice blocks break off from the ice sheet of Antarctica and drift towards the open ocean. North temperature characteristics waters are determined by monsoon air circulation. In summer, temperature anomalies are observed here, when the Somali Current cools surface water up to a temperature of 21-23°C. In the eastern part of the ocean at the same geographical latitude, the water temperature is 28 ° C, and the highest temperature mark - about 30 ° C - was recorded in the Persian Gulf and the Red Sea. The average salinity of ocean waters is 34.8‰. The most salty waters are the Persian Gulf, the Red and Arabian Seas: this is due to intensive evaporation with a small amount of fresh water brought into the seas by rivers.

The 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 semi-diurnal.

Ice forms at 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 sedimentsthe Indian 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 the dissected relief is distributed - discontinuous distribution. The most widely represented are foraminiferal (on continental slopes, ridges, and at the bottom of most basins at depths up to 4700 m), diatoms (south of 50° S), radiolarian (near the equator), and coral sediments. Polygenic sediments - red deep-sea clays - are distributed south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of the continents. Chemogenic sediments are mainly represented by ferromanganese nodules, while riftogenic sediments are represented by destruction products of deep rocks. Outcrops of bedrocks 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 have been found, representing a slightly altered substance of the Earth's upper mantle.

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 (Sonda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and continue in the corresponding structures of Indochina and rifts of East Africa. These main macrostructures, which differ sharply in morphology, the structure of the earth's crust, seismic activity, and volcanism, are subdivided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, blocky ridges, volcanic ridges, sometimes topped with coral islands and banks (Chagos, Maldives, etc.). .), trench-faults (Chagos, Ob, etc.), often confined to the foot of blocky ridges (East Indian, West Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the bed of the Indian Ocean, a special place (according to the presence of continental rocks - granites of the Seychelles and the continental type of the earth's crust) is occupied by Northern part The Mascarene Range is a structure that is apparently part of the ancient mainland of Gondwana.


. Minerals


The most important minerals of the Indian Ocean are oil and natural gas. Their deposits are found on the shelves of the Persian and Suez Gulfs, in the Bass Strait, on the shelf of the Hindustan Peninsula. In terms of reserves and production of these minerals, the Indian Ocean ranks first in the world. On the coasts of Mozambique, the islands of Madagascar and Ceylon, ilmenite, monazite, rutile, titanite and zirconium are exploited. Off the coast of India and Australia there are deposits of barite and phosphorite, and in the shelf zones of Indonesia, Thailand and Malaysia, deposits of cassiterite and ilmenite are exploited on an industrial scale. On the shelves - oil and gas (especially the Persian Gulf), monazite sands (the coastal region of Southwestern India), etc.; in reef zones - ores of chromium, iron, manganese, copper, etc.; on the bed - huge accumulations of ferromanganese nodules.


. Climateindian ocean


Most of the Indian Ocean is located in warm climatic zones - equatorial, subequatorial and tropical. Only him southern regions located at high latitudes, are strongly influenced by Antarctica. The equatorial climate zone of the Indian Ocean is characterized by a constant predominance of humid warm equatorial air. Average monthly temperatures range here 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 and more.


. Flora and fauna


The most dangerous mollusks in the world live in the Indian Ocean - 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 water area of ​​the Indian Ocean lies within the tropical and southern temperate zones. The shallow waters of the tropical zone are characterized by numerous 6- and 8-ray corals, hydrocorals, capable of creating islands and atolls together with calcareous red algae. The richest fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral fish live among the powerful coral structures. Most of the coasts are occupied by mangroves, in which the mud jumper stands out - a fish that can exist in the air for a long time. The fauna and flora of the beaches and rocks that dry out at low tide are quantitatively depleted as a result of the depressing effect of the sun's rays. In the temperate zone, life on such stretches of coasts is much richer; dense thickets of red and brown algae (kelp, fucus, reaching the huge size of microcystis) develop here, various invertebrates are abundant. For the open spaces of the Indian Ocean, especially for the surface layer of the water column (up to 100 m), rich flora is also characteristic. Of the unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause the so-called water bloom during mass development.

The bulk of the ocean's animals are copepods (more than 100 species), followed by pteropods, jellyfish, siphonophores, and other invertebrates. Of the unicellular, radiolarians are characteristic; numerous squids. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, dolphins, 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 frigates, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and the islands that lie in the temperate zone of the ocean.

At night, the surface of the Indian Ocean shimmers with lights. Light is produced by small sea ​​plants called dinoflagellates. Luminous areas sometimes have the shape of a wheel with a diameter of 1.5 m.

. Fishing and marine industry


Fishing is underdeveloped (the catch does not exceed 5% of the world catch) and is limited to the local coastal zone. Near the equator (Japan) is fishing for tuna, and in Antarctic waters - whale fishing. In Sri Lanka, on the Bahrain Islands and on the northwestern coast of Australia, pearls and mother-of-pearl are mined.

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 know the world. Geography” V.A. Markin

3.slovari.yandex.ru ~ TSB books / Indian Ocean /

4.Big Encyclopedic Dictionary of Brockhaus F.A., Efron I.A.


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