Fauna of the Atlantic Ocean. Where is the Atlantic Ocean

ATLANTIC OCEAN(Latin name Mare Atlanticum, Greek 'Ατλαντίς - denoted the space between the Strait of Gibraltar and the Canary Islands, the whole ocean was called Oceanus Occidentalis - Western ok.), the second largest ocean on Earth (after the Pacific ok.), part World approx. Modern name first appeared in 1507 on the map of the Lorraine cartographer M. Waldseemüller.

Physical-geographical sketch

General information

In the north, the border of A. o. with the Arctic basin approx. runs along the east. Hudson Strait entrance, then through Davis Strait. and along the coast. Greenland to Cape Brewster, through the Danish Strait. to Cape Rydinupyur on about. Iceland, along its coast to Cape Herpirs (Terpirs), then to the Faroe Islands, then to the Shetland Islands and along 61 ° N. sh. to the coast of the Scandinavian Peninsula. In the east of A. about. bounded by the shores of Europe and Africa, in the west - by the shores of the North. America and South. America. The border of A. o. with Indian ca. carried out along the line passing from Cape Igolny along the meridian 20 ° E. to the coast of Antarctica. The border with the Pacific carried out from Cape Horn along the meridian 68 ° 04′ W. or the shortest distance from Yuzh. America to the Antarctic Peninsula through the strait. Drake, from Fr. Oste to Cape Sternek. South part A. o. sometimes called the Atlantic sector of the Southern Ocean, drawing the border along the subantarctic zone. convergence (approximately 40° S). In some works division A. about is offered. to Sev. and Yuzh. The Atlantic Oceans, but it is more common to consider it as a single ocean. A. o. - the most biologically productive of the oceans. It contains the longest underwater ocean. ridge - Mid-Atlantic Ridge; the only sea that does not have solid shores, limited by currents - Sargasso Sea; Hall. fandi with the highest tidal wave; to the basin of A. o. applies Black Sea with a unique hydrogen sulfide layer.

A. o. stretches from north to south for almost 15 thousand km, its smallest width is approx. 2830 km in the equatorial part, the largest - 6700 km (along the parallel of 30 ° N). Area A. o. with seas, bays and straits 91.66 million km 2, without them - 76.97 million km 2. The volume of water is 329.66 million km 3, without seas, bays and straits - 300.19 million km 3. Wed depth 3597 m, maximum - 8742 m (chute Puerto Rico). The most easily accessible for development shelf zone of the ocean (with depths up to 200 m) occupies approx. 5% of its area (or 8.6%, if we take into account the seas, bays and straits), its area is larger than in the Indian and Pacific Oceans, and significantly less than in the Arctic Ocean. Areas with depths from 200 m to 3000 m (continental slope zone) occupy 16.3% of the ocean area, or 20.7%, taking into account the seas and bays, more than 70% - the ocean floor (abyssal zone). See map.

Seas

In the basin of A. o. - numerous. seas, which are divided into: internal - Baltic, Azov, Black, Marmara and Mediterranean (in the latter, in turn, the seas are distinguished: Adriatic, Alboran, Balearic, Ionian, Cypriot, Ligurian, Tyrrhenian, Aegean); interisland - Irish and int. sea ​​west. the coast of Scotland; marginal - Labrador, Northern, Sargasso, Caribbean, Scotia (Scotia), Weddell, Lazarev, zap. part of Riiser-Larsen (see separate articles on the seas). The largest bays of the ocean: Biscay, Bristol, Guinean, Mexican, Maine, St. Lawrence. The most important straits of the ocean: Great Belt, Bosphorus, Gibraltar, Dardanelles, Danish, Davis, Drake, Øresund (Sund), Cabota, Kattegat, Kerch, English Channel (including Pas de Calais), Lesser Belt, Messinian, Skagerrak , Florida, Yucatan.

Islands

Unlike other oceans, in A. o. there are few seamounts, guyots and coral reefs, and there are no coastal reefs. The total area of ​​\u200b\u200bthe islands of A. o. OK. 1070 thousand km 2. Main groups of islands are located on the outskirts of the continents: British (Great Britain, Ireland, etc.) - the largest in area, Greater Antilles (Cuba, Haiti, Jamaica, etc.), Newfoundland, Iceland, the Tierra del Fuego archipelago (Land of Fire, Oste, Navarino) , Marajo, Sicily, Sardinia, Lesser Antilles, Falkland (Malvinas), Bahamas, etc. Small islands are found in the open ocean: Azores, Sao Paulo, Ascension, Tristan da Cunha, Bouvet (on the Mid-Atlantic Ridge), etc. .

coast

Coastline in the north. parts of A. o. heavily indented (see also Shore ), almost all major inland seas and bays are located here, in the south. parts of A. o. the banks are slightly indented. The coast of Greenland, Iceland and the coast of Norway preim. tectonic-glacial division of fjord and fiard types. To the south, in Belgium, they give way to sandy shallow shores. Coast of Flanders arr. arts. origin (coastal dams, polders, canals, etc.). The coast of UK and about. Ireland abrasion-bay, high limestone cliffs alternate with sandy beaches and muddy lands. The Cotentin Peninsula has rocky shores, sandy and gravel beaches. Sev. the coast of the Iberian Peninsula is composed of rocks, to the south, off the coast of Portugal, sandy beaches predominate, often fencing off lagoons. Sandy beaches also border the shores of the West. Sahara and Mauritania. To the south of Cape Zeleny there are leveled abrasion-bay shores with mangrove thickets. Zap. the Ivory Coast section has an accumulative coast with rocky headlands. To the southeast, to the vast delta of the river. Niger, - accumulative coast with means. the number of spits, lagoons. In the southwest Africa - accumulative, less often abrasion-bay shores with extensive sandy beaches. The shores of southern Africa of the abrasion-bay type are composed of solid crystalline. breeds. Coasts of the Arctic. Canadas are abrasive, with high cliffs, glacial deposits and limestones. In east. Canada and sowing. parts of the hall. St. Lawrence are intensively eroded limestone and sandstone cliffs. To the west and south of the hall. St. Lawrence - wide beaches. On the shores of the Canadian provinces of Nova Scotia, Quebec, Newfoundland - outcrops of solid crystalline. breeds. From about 40 ° N. sh. to Cape Canaveral in the USA (Florida) - alternation of leveled accumulative and abrasion types of coasts, composed of loose rocks. Coast of the Gulf of Mexico. low-lying, bordered by mangroves in Florida, sand barriers in Texas, and deltaic shores in Louisiana. On the Yucatan Peninsula - cemented beach sediments, to the west of the peninsula - an alluvial-marine plain with coastal ridges. On the coast of the Caribbean Sea, abrasion and accumulation areas alternate with mangrove swamps, alongshore barriers, and sandy beaches. South of 10° N. sh. accumulative banks are common, composed of material carried out from the mouth of the river. Amazon and other rivers. In the northeast of Brazil - a sandy coast with mangroves, interrupted by river estuaries. From Cape Kalkanyar to 30°S sh. - high deep coast of abrasion type. To the south (off the coast of Uruguay) there is an abrasion-type coast composed of clays, loess and sand and gravel deposits. In Patagonia, the coasts are represented by high (up to 200 m) cliffs with loose deposits. The shores of Antarctica are 90% composed of ice and belong to the ice and thermal abrasion type.

Bottom relief

At the bottom of A. o. distinguish the following major geomorphological. provinces: the underwater margin of the continents (shelf and continental slope), the ocean floor (deep basins, abyssal plains, zones of abyssal hills, uplifts, mountains, deep-sea trenches), mid-oceanic. ridges.

The boundary of the continental shelf (shelf) A. o. takes place on Wed. at depths of 100–200 m, its position can vary from 40–70 m (near Cape Hatteras and the Florida Peninsula) to 300–350 m (Cape Weddell). The shelf width is from 15–30 km (northeast of Brazil, Iberian Peninsula) to several hundred km (Northern Sea, Gulf of Mexico, Newfoundland Bank). In high latitudes, the shelf relief is complex and bears traces of glacial influence. Numerous uplifts (banks) are separated by longitudinal and transverse valleys or trenches. Off the coast of Antarctica on the shelf are ice shelves. At low latitudes, the shelf surface is more even, especially in the areas where terrigenous material is carried out by rivers. It is crossed by transverse valleys, often turning into canyons of the continental slope.

The slope of the continental slope of the ocean is cf. 1–2° and varies from 1° (areas of Gibraltar, the Shetland Islands, parts of the coast of Africa, etc.) to 15–20° off the coast of France and the Bahamas. The height of the continental slope varies from 0.9–1.7 km near the Shetland Islands and Ireland to 7–8 km in the area of ​​the Bahamas and the Puerto Rico Trench. Active margins are characterized by high seismicity. The surface of the slope is dissected in places by steps, ledges and terraces of tectonic and accumulative origin and longitudinal canyons. At the foot of the continental slope, gently sloping hills are often located. up to 300 m and shallow underwater valleys.

In the middle part of the bottom of A. o. is the largest mountain system of the Mid-Atlantic Ridge. It extends from about. Iceland to about. Bouvet at 18,000 km. The width of the ridge is from several hundred to 1000 km. The crest of the ridge runs close to the midline of the ocean, dividing it to the east. and app. parts. On both sides of the ridge there are deep-sea basins separated by bottom uplifts. In zap. parts of A. o. Basins are distinguished from north to south: Labradorskaya (with depths of 3000–4000 m); Newfoundland (4200–5000 m); North American Basin(5000–7000 m), which includes the abyssal plains of Som, Hatteras and Nares; Guiana (4500–5000 m) with the Demerara and Ceara plains; brazilian basin(5000–5500 m) with the abyssal plain of Pernambuco; Argentinean (5000–6000 m). In east. parts of A. o. basins are located: Western European (up to 5000 m), Iberian (5200–5800 m), Canary (over 6000 m), Zeleniy Cape (up to 6000 m), Sierra Leone (about 5000 m), Guinea (over 6000 m). 5000 m), Angolan (up to 6000 m), Cape (over 5000 m) with the abyssal plains of the same name. To the south is the African-Antarctic Basin with the abyssal Weddell Plain. The bottoms of deep-water basins at the foot of the Mid-Atlantic Ridge are occupied by the zone of abyssal hills. The basins are separated by the Bermuda, Rio Grande, Rockall, Sierra Leone, and other uplifts, and by the Kitovy, Newfoundland, and other ridges.

Seamounts (isolated conical elevations 1,000 m or more high) at the bottom of the sea. concentrated preim. in the Mid-Atlantic Ridge. In the deep-sea part, large groups of seamounts are found north of Bermuda, in the Gibraltar sector, off the northeast. ledge South. America, in the Guinea Hall. and west of South. Africa.

Deep sea trenches of Puerto Rico, Caiman(7090 m), South Sandwich Trench(8264 m) are located near the island arcs. gutter Romansh(7856 m) is a major fault. The steepness of the slopes of deep-sea trenches is from 11° to 20°. The bottom of the troughs is flat, leveled by accumulation processes.

Geological structure

A. o. arose as a result of the collapse of the Late Paleozoic supercontinent Pangea during the Jurassic. It is characterized by a sharp predominance of passive margins. A. o. borders on adjacent continents transform faults south of about. Newfoundland, along the north. coast of the Gulf of Guinea., along the Falkland underwater plateau and the Agulhas plateau in the south. parts of the ocean. Active margins are observed at areas (in the region of the Lesser Antilles arc and the arc of the South Sandwich Islands), where the subsidence occurs ( subduction) lithosphere A. o. The Gibraltar subduction zone, limited in length, has been identified in the Gulf of Cadiz.

In the Mid-Atlantic Ridge, the bottom is moving apart ( spreading) and the formation of oceanic. bark at a rate of up to 2 cm per year. Characterized by high seismic and volcanic. activity. In the north, paleospreading ridges branch off from the Mid-Atlantic Ridge into Cape Labrador and into the Bay of Biscay. In the axial part of the ridge, a rift valley is pronounced, which is absent in the extreme south and on the b. including the Reykjanes Ridge. Within its limits - volcanic. uplifts, solidified lava lakes, basaltic lava flows in the form of pipes (pillow-basalts). To the Center. The Atlantic found fields of metal-bearing hydrotherm, many of which form hydrothermal structures at the outlet (composed of sulfides, sulfates, and metal oxides); installed metaliferous sediments. At the foot of the slopes of the valley there are screes and landslides, consisting of blocks and crushed stone of oceanic rocks. bark (basalts, gabbro, peridotites). The age of the crust within the Oligocene ridge is modern. The Mid-Atlantic Ridge separates the zones west. and east. abyssal plains, where oceanich. The basement is covered by a sedimentary cover, the thickness of which increases in the direction of the continental foothills up to 10–13 km due to the appearance of older horizons in the section and the influx of clastic material from land. In the same direction, the age of the oceans is increasing. crust, reaching the Early Cretaceous (north of Middle Jurassic Florida). Abyssal plains are practically aseismic. The Mid-Atlantic Ridge is crossed by numerous transform faults leading to adjacent abyssal plains. The thickening of such faults is observed in the equatorial zone (up to 12 per 1700 km). The largest transform faults (Vima, São Paulo, Romansh, etc.) are accompanied by deep incisions (troughs) on the ocean floor. The entire section of the oceanic is opened in them. crust and partially upper mantle; protrusions (cold intrusions) of serpentinized peridotites are widely developed, forming ridges elongated along the strike of the faults. Mn. transform faults are transoceanic, or main (demarcation). In A. o. there are so-called. intraplate uplifts represented by underwater plateaus, aseismic ridges and islands. They have an oceanic a bark of the increased power also have hl. arr. volcanic origin. Many of them were formed as a result of the action mantle plumes; some originated at the intersection of the spreading ridge by large transform faults. To the volcanic uplifts include: about. Iceland, about Bouvet, oh Madeira, the Canary Islands, the Cape Verde, the Azores, the paired uplifts of Sierra and Sierra Leone, the Rio Grande and the Whale Range, the Bermuda Uplift, the Cameroon group of volcanoes, and others. there are intraplate uplifts of non-volcanic. nature, which includes the underwater plateau of Rockall, separated from the British Isles by the same name. trog. The plateau represents microcontinent, detached from Greenland in the Paleocene. Another microcontinent that also broke away from Greenland is the Hebrides in northern Scotland. The underwater marginal plateaus off the coast of Newfoundland (Great Newfoundland, Flemish Cap) and off the coast of Portugal (Iberian) separated from the continents as a result of rifting at the end of the Jurassic - the beginning of the Cretaceous.

A. o. is divided by transoceanic transform faults into segments having different time disclosure. From north to south, the Labrador-British, Newfoundland-Iberian, Central, Equatorial, Southern and Antarctic segments are distinguished. The opening of the Atlantic began in the Early Jurassic (about 200 million years ago) from the Central Segment. In the Triassic-Early Jurassic, oceanic spreading. the bottom was preceded by the continental rifting, traces of which are recorded in the form of semigrabens filled with clastic deposits on the Amer. and north - afri. the outskirts of the ocean. At the end of the Jurassic - the beginning of the Cretaceous, the Antarctic segment began to open up. In the early Cretaceous, spreading was experienced by Yuzh. segment in South. Atlantic and Newfoundland-Iberian segment in the North. Atlantic. The opening of the Labrador-British segment began at the end of the Early Cretaceous. At the end of the Late Cretaceous, the basin of the Labrador Sea arose here as a result of spreading on the side axis, which continued until the late Eocene. Sev. and Yuzh. The Atlantic united in the middle of the Cretaceous - Eocene during the formation of the Equatorial segment.

Bottom sediments

The thickness of the modern bottom sediments varies from a few m in the zone of the crest of the Mid-Atlantic Ridge to 5–10 km in the zones of transverse faults (for example, in the Romansh trench) and at the foot of the continental slope. In deep-sea basins, their thickness varies from several tens to 1000 m. St. 67% of the area of ​​the ocean floor (from Iceland in the north to 57–58 ° S) is covered with calcareous deposits formed by the remains of shells of planktonic organisms (main sample foraminifera, coccolithophorid). Their composition varies from coarse sands (at depths up to 200 m) to silts. At depths greater than 4500–4700 m, calcareous muds are replaced by polygenic and siliceous planktonic sediments. The first take approx. 28.5% of the ocean floor area, lining the bottom of the basins, and represented red deep ocean clay(deep-sea clay silts). These sediments contain the amount of manganese (0.2–5%) and iron (5–10%) and a very small amount of carbonate material and silicon (up to 10%). Siliceous planktonic sediments occupy approx. 6.7% of the ocean floor area, of which diatom silts (formed by the skeletons of diatoms) are the most common. They are common off the coast of Antarctica and on the shelf of the Southwest. Africa. Radiolarian oozes (formed by skeletons of radiolarians) meet hl. arr. in the Angolan Basin. Along the coasts of the ocean, on the shelf and partly on the continental slopes, terrigenous sediments of various compositions (gravel-pebble, sandy, clayey, etc.) are developed. The composition and thickness of terrigenous sediments are determined by the bottom relief, the activity of solid material supply from land, and the mechanism of their transfer. Glacial precipitation carried by icebergs is distributed along the coast of Antarctica, about. Greenland, about. Newfoundland, Labrador Peninsula; composed of weakly sorted detrital material with the inclusion of boulders, mostly in the south of the A. o. Sediments (from coarse sand to silt) formed from pteropod shells are often found in the equatorial part. Coral sediments (coral breccias, pebbles, sands and silts) are localized in the Gulf of Mexico, the Caribbean Sea and near the northeast. the coasts of Brazil; their ultimate depth is 3500 m. Volcanic sediments are developed near the volcanic. islands (Iceland, Azores, Canaries, Cape Verde, etc.) and are represented by fragments of volcanic. rocks, slag, pumice, volcanic. ashes. Modern chemogenic sediments are found on the Great Bahama Bank, in the Florida-Bahamas, Antilles regions (chemogenic and chemogenic-biogenic carbonates). In the basins of the North American, Brazilian, Green Cape there are ferromanganese nodules; their composition in AO: manganese (12.0–21.5%), iron (9.1–25.9%), titanium (up to 2.5%), nickel, cobalt, and copper (tenths of a percent ). Phosphorite concretions appear at depths of 200–400 m near the east. US coast and north-west. coast of Africa. Phosphorites are distributed along the east. coast of A. o. - from the Iberian Peninsula to Cape Agulhas.

Climate

Due to the large length of A. o. its waters are located in almost all natural climates. zones - from the subarctic in the north to the antarctic in the south. From the north and south, the ocean is widely open to the influence of the Arctic. and antarctic. waters and ice. The lowest air temperature is observed in the polar regions. Over the coast of Greenland, the temperature can drop to -50 ° C, and in the south. part of Cape Weddell recorded a temperature of -32.3 °C. In the equatorial region, the air temperature is 24–29 ° C. The pressure field over the ocean is characterized by a successive change of stable large baric formations. Above the ice domes of Greenland and Antarctica - anticyclones, in temperate latitudes North. and Yuzh. hemispheres (40–60°) - cyclones, at lower latitudes - anticyclones, separated by a zone of low pressure near the equator. This baric structure supports tropical. and equatorial latitudes steady winds east. directions (trade winds), in temperate latitudes - strong winds west. directions, which received the names of the sailors. "roaring forties". Strong winds are also characteristic of the Bay of Biscay. In the equatorial region, the interaction of the sowing. and south. baric systems leads to frequent tropical. cyclones (tropical hurricanes), the greatest activity of which is observed from July to November. Tropical horizontal dimensions. cyclones up to several hundred km. The wind speed in them is 30–100 m/s. They move, as a rule, from east to west at a speed of 15-20 km / h and reach their greatest strength over the Caribbean and the Gulf of Mexico. In areas of low pressure in temperate and equatorial latitudes, precipitation is frequent and heavy clouds are observed. So, at the equator, St. 2000 mm of precipitation per year, in temperate latitudes - 1000–1500 mm. In areas of high pressure (subtropics and tropics), the amount of precipitation decreases to 500–250 mm per year, and in areas adjacent to the desert coasts of Africa and in the South Atlantic High, to 100 mm or less per year. In areas where warm and cold currents meet, fogs are frequent, for example. in the Newfoundland Bank area and in the hall. La Plata.

Hydrological regime

Rivers and water balance With. In the basin of A. o. 19,860 km 3 of water are annually carried out by rivers, this is more than in any other ocean (about 45% of the total flow into the World Ocean). The largest rivers (with an annual flow of over 200 km 3): Amazon, Mississippi(flows into the Gulf of Mexico.), Saint Lawrence river, Congo, Niger, Danube(flows into the Black Sea) Paraná, Orinoco, Uruguay, Magdalena(flows into the Caribbean). However, the fresh water balance of A. o. negative: evaporation from its surface (100–125 thousand km 3 / year) significantly exceeds atmospheric precipitation (74–93 thousand km 3 / year), river and underground runoff (21 thousand km 3 / year) and ice melting and icebergs in the Arctic and Antarctic (about 3 thousand km 3 / year). The deficit of the water balance is compensated by the inflow of waters, Ch. arr. from the Pacific Ocean, through the Drake Strait with the course of the West Winds, 3,470 thousand km 3 / year enter in Pacific ok. only 210 thousand km 3 / year go. From the Arctic ca. through numerous straits in A. about. 260 thousand km 3 / year and 225 thousand km 3 / year are supplied by the Atlantic. water flows back into the Arctic Ocean. Water balance with Indian c. negative, in the Indian apprx. with the course of the West Winds, 4976 thousand km 3 / year are taken out, and it comes back with the Coastal Antarctic. current, deep and bottom waters only 1692 thousand km 3 / year.

Temperature regime m. Wed. the temperature of the ocean waters as a whole is 4.04 ° C, and surface water 15.45°C. The distribution of water temperature on the surface is asymmetric with respect to the equator. The strong influence of the Antarctic. waters leads to the fact that the surface waters of the South. hemisphere is almost 6 ° C colder than the North, the warmest waters of the open part of the ocean (thermal equator) are between 5 and 10 ° N. sh., i.e., shifted north of the geographic. equator. Features of large-scale water circulation lead to the fact that the water temperature on the surface near the west. coasts of the ocean are about 5 °C higher than those of the east. The warmest water temperature (28–29 ° C) on the surface is in the Caribbean and the Gulf of Mexico. in August, the lowest - off the coast of about. Greenland, about. Baffin Island, Labrador Peninsula and Antarctica, south of 60 °, where even in summer the water temperature does not rise above 0 ° C. The temperature of the waters in the layer Ch. thermocline (600–900 m) is approx. 8–9 °C, deeper, in intermediate waters, descends at cf. up to 5.5 °C (1.5–2 °C in Antarctic intermediate waters). In deep waters, the water temperature in cf. 2.3 °C, in the bottom 1.6 °C. At the very bottom, the temperature of the water increases slightly due to geothermal. heat flow.

Salinity In the waters of A. o. contains approx. 1.1×10 16 tons of salts. Wed the salinity of the waters of the entire ocean is 34.6‰, and that of surface waters is 35.3‰. The highest salinity (over 37.5‰) is observed on the surface in the subtropical. areas where the evaporation of water from the surface exceeds its inflow with atmospheric precipitation, the smallest (6–20‰) in the mouth sections of large rivers flowing into the ocean. From the subtropics to high latitudes, salinity on the surface decreases to 32–33‰ under the influence of precipitation, ice, river and surface runoff. In temperate and tropical areas max. salinity values ​​are on the surface, an intermediate salinity minimum is observed at depths of 600–800 m. parts of A. o. are characterized by a deep salinity maximum (more than 34.9‰), which is formed by highly saline Mediterranean waters. Deep waters of A. o. have a salinity of 34.7–35.1‰ and a temperature of 2–4 °C, near-bottom, occupying the deepest depressions of the ocean, respectively 34.7–34.8‰ and 1.6 °C.

Density The density of water depends on temperature and salinity; temperature is of greater importance in the formation of the water density field. Waters with the lowest density are located in the equatorial and tropical regions. zones with a high water temperature and a strong influence of the flow of such rivers as the Amazon, Niger, Congo, etc. (1021.0–1022.5 kg / m 3). In the south part of the ocean, the density of surface waters increases to 1025.0–1027.7 kg/m 3 , in the northern part – up to 1027.0–1027.8 kg/m 3 . Density of deep waters A. o. 1027.8–1027.9 kg / m 3.

Ice regime m. In the north. parts of A. o. first-year ice is formed Ch. arr. in the inner seas of temperate latitudes, multi-year ice is carried out from the Arctic approx. The boundary of the distribution of the ice cover in the sowing. parts of A. o. varies considerably, in winter, pack ice can reach decomp. years 50–55°N sh. There is no ice in summer. Antarctic border. In winter, multi-year ice passes at a distance of 1600–1800 km from the coast (approximately 55 ° S), in summer (February-March) ice is found only in the coastal strip of Antarctica and in Cape Weddell. Main icebergs are supplied by the ice sheets and ice shelves of Greenland and Antarctica. The total mass of icebergs coming from the Antarctic. glaciers, estimated at 1.6 × 10 12 tons per year, main. their source is the Filchner Ice Shelf in Cape Weddell. From the glaciers of the Arctic to the A. O. icebergs with a total mass of 0.2–0.3 × 10 12 tons arrive per year, in the main. from the Jacobshavn glacier (near Disko Island off the western coast of Greenland). Wed arctic lifespan. icebergs approx. 4 years, Antarctic a little more. The border of distribution of icebergs in sowing. parts of the ocean 40 ° N. sh., but in otd. cases they were observed up to 31 ° C. sh. In the south part of the boundary passes at 40 ° S. sh., in the center. parts of the ocean and at 35 ° S. sh. on the app. and east. periphery.

I flow. Water circulation A. o. subdivided into 8 quasi-stationary oceanic. gyres located almost symmetrically about the equator. From low to high latitudes in the North. and Yuzh. hemispheres are tropical. anticyclonic, tropical cyclonic, subtropical anticyclonic, subpolar cyclonic. oceanic cycles. Their boundaries, as a rule, are Ch. oceanic currents. A warm current begins off the Florida Peninsula Gulfstream. Taking in the warm waters Antilles Current and Florida Current, the Gulf Stream heads northeast and splits into several branches at high latitudes; the most significant of them are Irminger Current, which carries warm water into Davis Strait, the North Atlantic Current, norwegian current, going to the Norwegian Sea and further to the northeast, along the coast of the Scandinavian Peninsula. To meet them from Devisova Prospekt. comes out cold Labrador Current, whose waters can be traced off the coast of America to almost 30 ° N. sh. From Danish Strait. the cold East Greenland current flows into the ocean. In low latitudes A. about. warm temperatures move from east to west northern trade winds and South trade winds, between them, approximately 10 ° N. sh., from west to east there is an Intertrade countercurrent, which is active Ch. arr. summer in Sev. hemisphere. separates from the southern trade winds brazilian current, which runs from the equator to 40 ° S. sh. along the coast of America. Sev. branch of the South trade wind currents forms Guiana Current, which is directed from south to northwest to the connection with the waters of the Northern trade winds. Off the coast of Africa from 20 ° N. sh. the warm Guinean current passes to the equator, in the summer the Inter-trade countercurrent connects with it. In the south parts of A. o. crosses the cold West winds flow(Antarctic circumpolar current), which is included in the A. about. through the strait Drake, descends to 40 ° S. sh. and goes to the Indian ca. south of Africa. The Falkland current separates from it, reaching along the coast of America almost to the mouth of the river. Parana, the Benguela Current, running along the coast of Africa almost to the equator. Cold canary current runs from north to south - from the shores of the Iberian Peninsula to the Cape Verde Islands, where it passes into the Northern trade winds.

Deep circulation during e. Deep circulation and structure of waters A. o. are formed as a result of a change in their density during cooling of waters or in zones of mixing of waters decomp. origin, where the density increases as a result of the mixing of waters with decomp. salinity and temp. Subsurface waters are formed in the subtropical. latitudes and occupy a layer with a depth of 100–150 m to 400–500 m, with a temperature of 10–22 °C and a salinity of 34.8–36.0‰. Intermediate waters are formed in the subpolar regions and are located at depths from 400–500 m to 1000–1500 m, with a temperature of 3 to 7 °C and a salinity of 34.0–34.9‰. The circulation of subsurface and intermediate waters is generally anticyclonic. character. Deep waters are formed in high latitudes. and south. parts of the ocean. Waters formed in the Antarctic region, have the highest density and spread from south to north in the bottom layer, their temperature varies from negative (in high southern latitudes) to 2.5 ° C, salinity 34.64–34.89‰. Waters formed in high sowing. latitudes, move from north to south in a layer from 1500 to 3500 m, the temperature of these waters is from 2.5 to 3 ° C, salinity is 34.71–34.99‰. In the 1970s V. N. Stepanov and, later, V. S. Broker substantiated the scheme of planetary interoceanic transfer of energy and matter, which received the name. "global conveyor" or "global thermohaline circulation of the World Ocean". According to this theory, the relatively salty North Atlantic. waters reach the coast of Antarctica, mix with supercooled shelf water and, passing through the Indian Ocean, end their journey in the sowing. parts of the Pacific Ocean.

Tides and waves e. Tides in A. o. preim. semi-diurnal. Tidal wave height: 0.2–0.6 m in the open part of the ocean, a few cm in the Black Sea, 18 m in the bay. Fundy (the northern part of the Gulf of Maine in North America) is the highest in the world. The height of wind waves depends on the speed, exposure time and wind acceleration; during strong storms it can reach 17–18 m. 22–26 m.

Flora and fauna

The large length of the A. O., the variety of climatic. conditions, that is. inflow of fresh water and large upwellings provide a variety of living conditions. In total, approx. 200 thousand species of plants and animals (of which fish are about 15,000 species, cephalopods are about 600 species, whales and pinnipeds are about 100 species). Life is distributed very unevenly in the ocean. There are three main the type of zonality of the distribution of life in the ocean: latitudinal, or climatic, vertical and circumcontinental. The density of life and its species diversity decrease with distance from the coast towards the open ocean and from the surface to deep waters. Species diversity also decreases from tropical. latitudes to high.

Planktonic organisms (phytoplankton and zooplankton) are the basis of the food chain in the ocean, osn. their mass lives in the upper zone of the ocean, where light penetrates. The highest plankton biomass is in high and temperate latitudes during spring and summer blooms (1–4 g/m3). During the year, biomass can change by 10–100 times. Main phytoplankton species - diatoms, zooplankton - copepods and euphausids (up to 90%), as well as chaetognaths, hydromedusae, ctenophores (in the north) and salps (in the south). At low latitudes, the plankton biomass varies from 0.001 g/m 3 in the centers of anticyclonics. gyres up to 0.3–0.5 g/m 3 in the Gulf of Mexico and Guinea. Phytoplankton is represented by Ch. arr. coccolithins and peridineas, the latter can develop in coastal waters in huge quantities, causing catastrophic. red tide phenomenon. Low-latitude zooplankton is represented by copepods, chaetognaths, hyperids, hydromedusae, siphonophores, and other species. There are no clearly pronounced dominant zooplankton species in low latitudes.

Benthos is represented by large algae (macrophytes), which b. hours grow at the bottom of the shelf zone to a depth of 100 m and cover approx. 2% of the total area of ​​the ocean floor. The development of phytobenthos is observed in those places where there are suitable conditions—soils suitable for fastening to the bottom, the absence or moderate speeds of near-bottom currents, and so on. main part of the phytobenthos is made up of kelp and red algae. In the temperate zone, parts of the sea, along the American and European coasts, are brown algae (fucus and ascophyllum), kelp, desmarestia, and red algae (furcellaria, ahnfeltia, and others). Zostera is common on soft soils. In the temperate and cold zones of the south. parts of A. o. brown algae predominate. In the tropical in the littoral zone, due to strong heating and intense insolation, vegetation on the ground is practically absent. A special place is occupied by the Sargasso Cape ecosystem, where floating macrophytes (mainly three species of algae of the genus Sargassum) form clusters on the surface in the form of ribbons ranging in length from 100 m to several. kilometers.

The main part of the nekton biomass (actively swimming animals - fish, cephalopods, and mammals) are fish. The largest number of species (75%) lives in the shelf zone; with depth and with distance from the coast, the number of species decreases. For cold and temperate zones are characteristic: from fish - dec. species of cod, haddock, saithe, herring, flounder, catfish, conger eel, etc., herring and polar sharks; from mammals - pinnipeds (harp seal, hooded seal, etc.), decomp. species of cetaceans (whales, sperm whales, killer whales, pilot whales, bottlenose whales, etc.).

There is a great similarity between the faunas of temperate and high latitudes of both hemispheres. At least 100 species of animals are bipolar, that is, they are characteristic of both temperate and high zones. For the tropical A.'s zones about. characteristic: from fish - dec. sharks, flying fish, sailboats, decomp. species of tuna and glowing anchovies; from animals - sea turtles, sperm whales, river dolphin inia; numerous and cephalopods - diff. species of squid, octopus, etc.

Deep-sea fauna (zoobenthos) A. o. represented by sponges, corals, echinoderms, crustaceans, mollusks, decomp. worms.

Research History

Allocate three stages of research And. The first is characterized by the establishment of the boundaries of the ocean and the discovery of its individual objects. AT 12- 5th century BC e. Phoenicians, Carthaginians, Greeks and Romans left descriptions of maritime wanderings and the first sea charts. Their voyages reached the Iberian Peninsula, England and the mouth of the Elbe. In the 4th c. BC e.Piteas(Pytheas) while sailing to the North. Atlantic, he determined the coordinates of a number of points and described the tidal phenomena in the A. O. By the 1st century n. e. include references to the Canary Islands. In the 9th-10th centuries. Normans (RowdyEirik and his son Leif Eirikson) crossed the ocean, visited Iceland, Greenland, Newfoundland and explored the shores of the North. America under 40° c. sh. In the eraGreat geographical discoveries(mid. 15th - mid. 17th centuries) navigators (mainly the Portuguese and Spaniards) mastered the way to India and China along the coast of Africa. The most outstanding voyages during this period were made by the Portuguese B.Diashem(1487), Genoese H.Columbus(1492–1503), the Englishman J.Cabot(1497) and the Portuguese Vasco dagama(1498); for the first time trying to measure the depths of the open parts of the ocean and the speed of surface currents. The first bathymetric map (depth map) was compiled in Spain in 1523. In 1520 F.Magellanfirst passed from A. o. in Pacific ok. strait, later named after him. In the 16th and 17th centuries Atlantic is intensively studied. coast of the North. America (English J.Davis, 1576–78, G. Hudson, 1610, W. Baffin, 1616, and other sailors whose names can be found on the map of the ocean). The Falkland Islands were discovered in 1591–92. South shores of A. o. - the mainland Antarctica - were discovered and first described by Rus. antarctic expedition F.F.Bellingshausen and M.P. Lazarevain 1819–21. This completed the study of the boundaries of the ocean.

The second stage is characterized by the study of physical. properties of ocean waters, temperature, salinity, currents, etc. In 1749, the Englishman G. Ellis made the first temperature measurements at various depths, repeated by the Englishman J. cook(1772), Swiss O. Saussure(1780), Russian. I.F. Kruzenshtern(1803) and others. In the 19th century. A. o. becomes a testing ground for testing new methods of studying depths, new equipment and new approaches to the organization of work. For the first time, bathometers, deep-sea thermometers, thermal depth gauges, deep-sea trawls and dredges are used. Of the most significant expeditions can be noted Rus. sailing on the ships "Rurik" (1815-18) and "Enterprise" (1823–26) under the direction of O. E.Kotzebue(1815–18); English on "Erebus" and "Terror" under the leadership of J.K.Ross(1840–43); Amer. on the "Arctic" under the leadership of M.F.Maury(1856). True complex oceanographic ocean exploration began with an expedition in English. corvette« Challenger "led by W. Thomson (1872-76). The following significant expeditions were carried out on the ships Gazelle (1874-76), Vityaz (1886-89), Valdivia (1898-99), Gauss (1901-03). From 1885 to 1922, a great contribution to the study of A. o. introduces Prince Albert I of Monaco, who organized and led expeditionary research on the yachts Irendel, Princess Alice, Irendel II, Princess Alice II in the north. parts of the ocean. In the same years he organized the Oceanographic Museum in Monaco. Since 1903, work began on the "standard" sections in the North Atlantic under the leadership of the International Council for the Study of the Sea (ICES) - the first international oceanographic. scientific organization that existed before the 1st World War.

The most significant expeditions between the world wars were carried out on the ships Meteor, Discovery II, Atlantis. In 1931, the International Council of Scientific Unions (ICSU) was formed, which is still active today and organizes and coordinates ocean research.

After the 2nd World War, the echo sounder began to be widely used to study the ocean floor. This made it possible to obtain the real picture topography of the ocean floor. In the 1950s–70s. carried out complex geophysical. and geological. A.'s research about. and established the features of the relief of its bottom and tectonics, the structure of the sedimentary strata. Many large forms of bottom topography (submarine ridges, mountains, trenches, fault zones, vast basins and uplifts) have been identified, and geomorphological data have been compiled. and tectonic. cards. Unique results were obtained under the IODP International Deep Sea Ocean Drilling Program (1961–2015, ongoing).

The third stage of ocean research is mainly aimed at studying its role in the global processes of matter and energy transfer and its influence on climate formation. Complexity and wide range research work demanded extensive international cooperation. The Scientific Committee for Oceanic Research (SCOR), formed in 1957, the Intergovernmental Oceanographic Commission of UNESCO (IOC), which has been operating since 1960, and other international organizations play an important role in coordinating and organizing international research. In 1957-58, a lot of work was carried out within the framework of the first International Geophysical Year (IGY). Subsequently, major international projects were aimed both at the study of individual parts of the AO, for example, EQUALANT I–III (1963–64), Polygon-70 (1970), SICAR (1970–75), POLYMODE (1977–78 ), and A. o. as parts of the World Ocean, for example, TOGA (1985–89), GEOSECS (1973–74), WOCE (1990–96), and others. the role of the ocean in the global carbon cycle and more. other questions. In con. 1980s owls. deep-sea submersibles"Peace» unique ecosystems of geothermal regions of the ocean rift zone were studied. If in the beginning 80s it was ok. 20 international ocean research projects, then by the 21st century. St. 100. The largest programs:« International Geosphere-Biosphere Program» (since 1986, 77 countries participate), it includes projects« Dynamics of global ocean ecosystems» (GLOBES, 1995–2010), "Global flows of matter in the ocean» (JGOFS, 1988–2003), " Land-ocean interaction in the coastal zone» (LOICZ), Integral Marine Biogeochemistry and Ecosystem Research (IMBER), Coastal Land-Ocean Interaction (LOICZ, 1993–2015), Ocean Surface-Lower Atmosphere Interaction Study (SOLAS, 2004–15, ongoing) ,« World Climate Research Program» (WCRP, since 1980, 50 countries participate), International Study of Biogeochemical Cycles and Large Scale Distribution of Trace Elements and Their Isotopes in the Marine Environment (GEOTRACES, 2006–15, ongoing), and more. etc. The Global Ocean Observing System (GOOS) is being developed. One of the main projects of the WCRP was the program "Climate and Ocean: Unsteadiness, Predictability and Variability" (CLIVAR, since 1995), which was based on the results of TOGA and WOCE. Ros. For many years, scientists have been conducting expeditionary studies of exchange processes at the border of the A. O. and the Arctic Ocean, circulation in the Drake Passage, distribution of cold Antarctic waters along deep-sea faults. Since 2005, the international ARGO program has been operating, in which observations are carried out by autonomous sounding instruments throughout the World Ocean (including AO), and the results are transmitted via artificial Earth satellites to data centers.

In November 2015, for the first time in the last 30 years, Ross made a voyage from Kronstadt to the shores of Antarctica. research vessel of the Baltic Fleet "Admiral Vladimirsky". It made a transition with a length of over 34 thousand sea. miles. Along the route, hydrographic, hydrological, hydrometeorological and radio navigation studies were carried out, information was collected to correct marine navigation charts, navigation manuals and manuals. Having rounded the southern tip of the African continent, the ship entered the marginal seas of Antarctica. He moored near the station "Progress", scientists exchanged with the staff of the station data on monitoring the ice conditions, the melting of the Arctic ice, the weather. The expedition ended on 15.4.2016. In addition to the crew, hydrographers of the 6th Atlantic oceanographic department took part in the expedition. hydrographic expeditions. services of the Baltic Fleet, employees of Ros. state hydrometeorological University, the Institute of the Arctic and Antarctic, etc. The work on the creation of the third part of the Oceanographic Atlas WOCE (The World Ocean Circulation Experiment), dedicated to the Atlantic Ocean, was completed, the presentation of which took place in February 2015 at the IO RAS named after A.I. P. P. Shirshova.

Economic use

A. o. occupies an important place in the world economy among other oceans of our planet. Man's use of the sea, as well as other seas and oceans, follows several basic principles. directions: transport and communications, fishing, mining. resources, energy, recreation.

Transport

Already within 5 centuries A. about. occupies a leading role in maritime transport. With the opening of the Suez (1869) and Panama (1914) canals, short sea routes appeared between the Atlantic, Indian and Pacific oceans. To the share of A. o. accounts for approx. 3/5 of the cargo turnover of world shipping, in con. 20th century up to 3.5 billion tons of cargo per year was transported through its waters (according to IOC). OK. 1/2 of the volume of traffic is oil, gas and oil products, followed by general cargo, then iron ore, grain, coal, bauxite and alumina. Ch. the direction of transportation is the North Atlantic, which runs between 35–40 ° N. sh. and 55–60° N. sh. Main shipping routes connect the port cities of Europe, the USA (New York, Philadelphia) and Canada (Montreal). This direction adjoins the sea routes of the Norwegian, Northern and int. seas of Europe (Baltic, Mediterranean and Black). Transported to the main raw materials (coal, ores, cotton, timber, etc.) and general cargo. Dr. important directions of transportation - South Atlantic: Europe - Central (Panama, etc.) and South America (Rio de Janeiro, Buenos Aires); East Atlantic: Europe - South Africa (Cape Town); west-Atlantic: Sev. America, South America is southern Africa. Before the reconstruction of the Suez Canal (1981) b. hours of oil tankers from the Indian basin approx. was forced to go around Africa.

The transportation of passengers occupies an important place in the A. about. since the 19th century, when mass emigration from the Old World to America began. The first steam-sailing vessel, the Savannah, crossed the A. O. for 29 days in 1819. At the beginning. 19th century The Blue Ribbon Prize was established for passenger ships that will cross the ocean the fastest. This prize was awarded, for example, to such famous liners as Lusitania (4 days and 11 hours), Normandie (4 days and 3 hours), Queen Mary (4 days without 3 minutes). The last time the "Blue Ribbon" was awarded to the Amer. liner "United States" in 1952 (3 days and 10 hours). In the beginning. 21st century the duration of a passenger liner flight between London and New York is 5–6 days. Max. passenger transportation through A. o. fell on 1956–57, when more than 1 million people were transported a year; The majority of passengers prefer air transport (the record flight time for the Concorde supersonic airliner on the New York-London route is 2 hours 54 minutes). The first non-stop flight through A. about. committed 14-15.6.1919 English. pilots J. Alcock and A. W. Brown (Newfoundland - Ireland), the first non-stop flight through the A. about. alone (from continent to continent) 20–21.5.1927 – Amer. pilot C. Lindberg (New York - Paris). In the beginning. 21st century practically the entire flow of passengers through A. o. served by aviation.

Connection

In 1858, when there was no radio communication between the continents, through A. o. The first telegraph cable was laid. To con. 19th century 14 telegraph cables connected Europe with America and 1 with Cuba. In 1956, the first telephone cable was laid between the continents, by the mid-1990s. at the bottom of the ocean, St. 10 telephone lines. In 1988, the first transatlantic fiber-optic communication line was laid, at the beginning of the 21st century. there are 8 lines.

Fishing

A. o. considered the most productive ocean, its biological. resources are exploited by man most intensively. In A. o. fishing and seafood production account for 40–45% of the total world catch (area approx. 25% of the world approx.). The majority of the catch (up to 70%) consists of herring fish (herring, sardines, etc.), cod fish (cod, haddock, hake, whiting, saithe, saffron cod, etc.), flounder, halibut, and sea bass. Production of shellfish (oysters, mussels, squids, etc.) and crustaceans (lobsters, crabs) approx. eight%. According to FAO estimates, the annual catch of fish products in the A. about. is 85–90 million tons, but for most of the fishing areas of the Atlantic, the fish catch reached in the middle. 1990s its maximum and its increase is undesirable. The traditional and most productive fishing area is the north-east. part of the Arctic Ocean, including the North and Baltic Seas (mainly herring, cod, flounder, sprats, and mackerel). In the north-west. area of ​​the ocean, on the Newfoundland banks, cod, herring, flounder, squid, etc. have been harvested for many centuries. In the center. parts of A. o. there is a catch of sardine, horse mackerel, mackerel, tuna, etc. In the south, on the Patagono-Falkland shelf elongated along the latitude, fishing for both warm-water species (tuna, marlin, swordfish, sardines, etc.) and cold-water species (blue whiting, hake , notothenia, toothfish, etc.). Off the coast of and southwest. African catch of sardine, anchovy and hake. In the Antarctic area of ​​the ocean, planktonic crustaceans (krill), marine mammals, fish - notothenia, toothfish, silverfish, etc. are of commercial importance. 20th century in high-latitude sowing. and south. areas of the ocean were active fishing decomp. species of pinnipeds and cetaceans, but in recent decades it has declined sharply due to the depletion of biological. resources and thanks to environmental activities, including intergovernmental ones. agreements to limit their production.

Mineral resources

Miner is being developed more and more actively. wealth of the ocean floor. Deposits of oil and combustible gas have been studied more fully; belong to 1917, when oil production began in the industrial. scales in east. parts of the Maracaibo lagoon (Venezuela). The largest centers of marine production: the Venezuelan Gulf, the Maracaibo lagoon ( Maracaiba oil and gas basin), Mexican Hall. ( Gulf of Mexico oil and gas basin), Hall. Pariah ( Orinok oil and gas basin), Brazilian shelf (Sergipe-Alagoas oil and gas basin), Gulf of Guinea. ( Gulf of Guinea oil and gas basin), Northern m. ( North Sea oil and gas region), etc. Alluvial deposits of heavy minerals are widespread along many coasts. The largest development of alluvial deposits of ilmenite, monocyte, zircon, rutile are carried out off the coast of Florida. Similar deposits are located in the Gulf of Mexico, off the east. US coasts, as well as Brazil, Uruguay, Argentina and the Falkland Islands. On the shelf southwest. Africa is developing coastal marine diamond placers. Gold-bearing placers were found off the coast of Nova Scotia at depths of 25–45 m. In A. o. one of the world's largest iron ore deposits, Wabana, has been explored (in Conception Bay off the coast of Newfoundland), and iron ore is also mined off the coast of Finland, Norway, and France. In the coastal waters of Great Britain and Canada, coal deposits are being developed, it is mined in mines located on land, the horizontal workings of which go under the seabed. On the shelf of the Gulf of Mexico. large sulfur deposits are being developed Gulf of Mexico sulfur-bearing province. In the coastal zone of the ocean, sand is mined for construction and production of glass, gravel. On the shelf east. US coasts and west. coasts of Africa, phosphorite-bearing sediments have been explored, but their development is still unprofitable. The total mass of phosphorites on the continental shelf is estimated at 300 billion tons. Large fields of ferromanganese nodules have been found at the bottom of the North American Basin and on the Blake Plateau; are estimated at 45 billion tons.

Recreational resources

From the 2nd floor. 20th century The use of recreational resources of the ocean is of great importance for the economies of coastal countries. Old resorts are being developed and new ones are being built. Since the 1970s ocean liners are laid down, intended only for cruises, they are distinguished by their large size (displacement of 70 thousand tons or more), an increased level of comfort and relative slowness. Main cruise ship routes A. o. - Mediterranean and caribbean and Mexican Hall. From con. 20 - early. 21st century scientific-tourist and extreme cruise routes are developing, mainly in the high latitudes of the North. and Yuzh. hemispheres. In addition to the Mediterranean and Black Sea basins, the main resort centers are located in the Canary, Azores, Bermuda Islands, in the Caribbean and the Gulf of Mexico.

Energy

The energy of sea tides A. o. is estimated at about 250 million kW. In the Middle Ages, tidal wave mills and sawmills were built in England and France. At the mouth of the river Rance (France) operates a tidal power plant. The use of the hydrothermal energy of the ocean (temperature difference in surface and deep waters) is also considered promising; a hydrothermal station operates on the coast of Côte d'Ivoire.

Port cities

On the banks of A. o. most of the world's major ports are located in Western Europe- Rotterdam, Marseille, Antwerp, London, Liverpool, Genoa, Le Havre, Hamburg, Augusta, Southampton, Wilhelmshaven, Trieste, Dunkirk, Bremen, Venice, Gothenburg, Amsterdam, Naples, Nantes-St. Nazaire, Copenhagen; all in. America - New York, Houston, Philadelphia, Baltimore, Norfolk - Newport, Montreal, Boston, New Orleans; in Yuzh. America - Maracaibo, Rio de Janeiro, Santos, Buenos Aires; in Africa - Dakar, Abidjan, Cape Town. Ros. port cities do not have direct access to the sea. and are located on the banks int. the seas belonging to its basin: St. Petersburg, Kaliningrad, Baltiysk (Baltic Sea), Novorossiysk, Tuapse (Black Sea).

The fauna of the Atlantic Ocean is rich in the diversity of its fauna. Thousands of species of animals are found in all layers of water and along the entire length.

Until the middle of the last century, the waters of the Atlantic Ocean were the leaders in catching seafood. However, their long-term production has reduced the resources of the Atlantic, now its share is 40% of the world's catch of fish and seafood, and now it ranks second in terms of catch after the Pacific Ocean.

Near the coast of Europe, in the north-eastern part of the ocean - the largest catches. The abundance of food, shallow depths, good illumination, the dynamics of coastal waters and the structural features of the bottom contribute to high biological activity in this part. The main fisheries here are catfish, squid, flounder, crabs, shrimps, spiny lobsters, mussels, scallops, herring, mackerel, perches, lobsters, snails, oysters and sprats.

In tropical latitudes, they are also engaged in the extraction of marine life, but not as plentifully as in temperate ones. Here, the interest for fishing is: some species of sharks, squids, shrimps, lobsters, mollusks, swordfish, tuna, turtles, etc.

Also, predators dangerous to humans live in tropical waters: sharks, barracudas and moray eels. The world of corals is also quite peculiar here, and off the coast of Cuba there are entire “underwater forests” - thickets of soft corals.

Various mammals also live in the Atlantic Ocean: dolphins, sperm whales, whales, porpoises, seals, etc. And sponges, annelids, crustaceans, starfish and sea lilies live in the deep-sea regions of the ocean.

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The Atlantic Ocean is the second largest ocean after the Pacific. The area occupied by its waters (together with the adjacent seas) is 91,140.8 thousand square kilometers.
The borders of the Atlantic Ocean stretch from east to west from Eurasia and Africa to the American continents, from north to south - from the islands of Greenland and Iceland to Antarctica.
The borders with the Indian, Pacific and Arctic Oceans are conditional and tied to certain geographical landmarks. It borders with the Indian Ocean strictly along the meridian from Cape Good Hope(the southern tip of Africa) to Antarctica, with the Pacific - from Cape Horn (the southern tip of South America) through the Drake Passage to the Antarctic Peninsula of Antarctica.
It is separated from the Arctic Ocean by the Davis Strait and the Danish Strait (from the east and west of Greenland), as well as the Faeroe-Icelandic Threshold, located on the shelf between Iceland and Europe.

You can see a complete map of the Atlantic Ocean.

This ocean is much deeper than the Arctic neighbor, its average depth is 3332 meters. The deepest place in the Atlantic - the South Sandwich Trench (near the Weddell Sea in the south) - from the surface of the ocean to the bottom of 8428 meters. Across the entire Atlantic Ocean from north to south stretches a large Mid-Atlantic Ridge, which determines, basically, the topography of the bottom of the entire ocean. On both sides of the ridge, between underwater plateaus and uplands, there are several large basins, with a depth of 3000 to 7300 meters.

Almost all inland, marginal seas and bays The Atlantics are located in the northern part of the ocean. There are many islands here, which are fragments of ancient continents, the coastline is heavily indented and winding. There are no large bays and inland seas in the south, with the exception of the Weddell Sea off the coast of Antarctica. The central part of the Atlantic Ocean is poor in islands. And those that occasionally get in the way of ships are small, of volcanic origin.

Since the ocean stretches across almost the entire hemisphere of the planet, the climate in its different regions is very different. But not only the proximity of the poles affects the climatic conditions in a particular area of ​​its water area. Powerful people also play an important role ocean currents, which carry large volumes of its waters. The west of the Atlantic Ocean is much warmer than its eastern part due to the warm current of the Gulf Stream and its branches - the North Atlantic, Antilles, Guiana and Brazilian currents.
In the eastern part of the ocean, along with warm currents, there are also large cold currents - the Canary and Bengal. All climatic zones pass through the Atlantic Ocean - from the equatorial to the subarctic (in the north) and the Antarctic (in the south).
Due to this climatic diversity, there is a huge number of life forms, especially in the upper layers of the ocean and in the coastal zone of the continents and islands.

The flora of the Atlantic includes both algae and flowering plants (Poseidonia, Zostera). In cold waters, various types of kelp predominate, in temperate waters - fucus, red algae (lithotamnion, rhodimenia, furcelaria) and zoster. There are few algae in tropical waters. Strong warming of the water and excessive illumination of the coastal bottom areas adversely affect the development of the flora. Nevertheless, the species diversity of vegetation in equatorial waters is ten times greater than the cold areas of the ocean. But the quantitative indicator is much lower than in temperate and northern latitudes. Phytoplankton actively develops throughout the ocean at a depth of up to 100 m.

The fauna of the Atlantic Ocean is represented by a wide variety of kingdoms, classes, families and species of animals. For the development of life forms, its waters over a larger area are very favorable. The very fact that the world catch in the Atlantic is almost equal to the catch in the Pacific, which is much larger than the Atlantic in area, speaks volumes. It makes no sense to list all the species of fish and animals that live in the Atlantic waters - this procedure will take a lot of time and site pages. We can only say that almost all representatives of the water world of the planet are present here. Unless some species have local distinctive features and differences with relatives from neighboring oceans.

The most important objects of fishing are herring, sardines, cod, groupers, flounders. Crustaceans are also mined: lobsters. crabs, lobsters, shrimp. From shellfish - oysters, mussels, squid, cuttlefish, etc.

If everything is less clear with life in the coastal zone, then life in the open ocean has its own characteristics.
The open ocean only at first glance seems sparsely populated and monotonous. In fact, on the surface of the water, as well as on land, there are areas that are sparsely populated and teeming with life. Life here, to a large extent, depends on microscopic creatures - phytoplankton, which is the basis of the food pyramid of the ocean and seas. As soon as this foundation disappears, the entire pyramid will collapse and all life in the oceans will perish.
Phytoplankton serves as food for zooplankton (radiolaria, sunflowers), which, in turn, feed on larger plankton (comb jelly, tiny crustaceans, larvae, etc.)
Large zooplankton is food for many small fish and for marine giants - whales, whale and giant sharks, etc. Large accumulations of small fish in the areas of flourishing zooplankton attract larger predators here - tuna, dolphins, predatory sharks. For tuna, marlin, swordfish, sailboats and toothed whales - killer whales, sperm whales rush here.

Schools of small fish attract not only the inhabitants of sea waters - gulls, cormorants, albatrosses and other sea birds in huge number flock to the general feast. The waste products of all these animals, as well as bird droppings, are a source of organic matter that feeds phytoplankton. This closes the food chain that sustains life in the ocean.

Phytoplankton is unevenly distributed in the ocean. Its amount in a particular area depends on the temperature of the water, the amount of sunlight and the availability of nutrients. Cool waters of temperate and even polar latitudes are more suitable for the development of phytoplankton than tropical warm waters. In the tropics, phytoplankton actively develops only in the zone of cold currents.
However, if in the tropics there are almost no seasonal fluctuations in the number of plankton, then in higher latitudes it actively reproduces and flourishes only in spring and summer, during the cold period the development of these organisms freezes. Because phytoplankton require sunlight to support photosynthesis in order to exist, these microorganisms live only in the upper layers of ocean and sea waters. Deeper than 100 m, where the sun's rays do not penetrate, phytoplankton does not live. But for nutrition, phytoplankton needs substances such as nitrogen and phosphorus. which are concentrated in the depths of the sea, inaccessible to phytoplankton. Waves, storms and storms mix sea water, supplying food for phytoplankton from the depths to the surface. This explains, in many respects, the fact that there is less phytoplankton in warm tropical waters. The reason lies in the fact that the warm waters of the upper layers of tropical seas are much lighter than the cold waters of the depths, which is why they do not sink lower, do not mix and do not supply microorganisms with the necessary trace elements for nutrition.

There is a lot of phytoplankton in the area of ​​the Cape Verde Islands (near the Senegalese coast of Africa). The cold Canarian current passes here, forming a cycle and good mixing of water layers.
In many places of the tropical latitudes of the Atlantic, especially above the deep-water plains (North American and Brazilian basins), the surface layers of water do not mix well with the lower layers, which prevents the development of phytoplankton. These areas are oceanic deserts, even large migrating animals such as whales, sailboats and others bypass them.

Among the inhabitants of the open oceanic waters of the Atlantic, many species of flying fish should be noted (16 species of these amazing creatures live here). For spawning, these inhabitants of the ocean expanses use any floating object - a piece of algae, a coconut, various debris, and even an air bubble of sailing jellyfish floating on the surface and a siphonophore (porpita, physalia). Flying fish are an object of hunting for oceanic predators - dolphin, tuna, which, in turn, are the desired prey of larger fish - marlin, sailfish, swordfish, sharks.
Sharks such as longfin, mako, blue, many species of gray and hammerhead sharks live in open ocean waters. These sharks have an extremely developed sense of smell, which allows them to smell food at a great distance, and are also capable of developing high speeds when moving.

An interesting inhabitant of the open ocean is the moon-fish. Its body resembles a large disc, equipped with large dorsal and anal fins. This fish has no tail fin at all. The moon-fish feeds on jellyfish, crustaceans, small squids. They often rest on the surface of the water, lying on their side. When the moon-fish swims close to the surface of the sea, the dorsal fin of this harmless fish sticking out of the water can be easily confused with the fin of a formidable sea predator - sharks.

A few words about life in the deep ocean - at the bottom of the ocean.
It should be noted that not much more is known about life in these places on our planet than about life on other planets. solar system. Of course, deep-sea vehicles with equipment and even people descend to the bottom of the deepest depressions and underwater gorges. But to say, on the basis of such sorties, that we have studied life in the depths of the ocean is the same as pulling out a few objects from pitch darkness with a flashlight beam, claiming that we have explored a palace immersed in darkness.

Of course, in the eternal darkness of the depths of the ocean, there are much fewer animals in quantitative terms, but there are incomparably more forms of life and various species of animals than at the surface. If in the upper layers in a section of the ocean there are 100 species of animals, then in the depths, in the same area, several times more can be counted. But the population density of the bottom is low.
Fish unusual for the upper layers live in the depths of the ocean - deep-sea anglerfish, chimeras, beaks, sacs, chiasmods and others. All of them have an unusual body shape for fish, colors. Many are equipped with luminous organs on the body, which serve to lure prey or scare off enemies. Other representatives of the animal world also live here: crustaceans, coelenterates, mollusks and other representatives of the fauna. Of the mammals, only the toothed whale, the sperm whale, can dive to depths of more than 1000 meters. For other animals that inhale atmospheric air, such journeys into the depths are beyond their strength.

We will start our journey across the Atlantic Ocean from its northernmost reservoir -

The Atlantic Ocean is the second largest and deepest. Its area is 91.7 million km2. The average depth is 3597 m, and the maximum depth is 8742 m. The length from north to south is 16,000 km.

Geographical position of the Atlantic Ocean

The ocean stretches from the Arctic Ocean in the north to the coast of Antarctica in the south. To the south, the Drake Passage separates the Atlantic from the Pacific. A characteristic feature of the Atlantic Ocean is the many inland and marginal seas in the Northern Hemisphere, the formation of which is mainly associated with tectonic movements of lithospheric plates. (Identify on the map "The structure of the earth's crust" the lithospheric plates within which the ocean is located.) The largest of the seas: Baltic, Black, Azov, Irish, Northern, Sargasso, Norwegian, Mediterranean. In total, there are more than 10 seas in the Atlantic Ocean. (Find Sargasso and the Mediterranean Sea on a physical map, compare their natural features.)

The Atlantic Ocean and its seas are washed by five continents. More than 70 states (in which over 2 billion people live) and 70% of the world's largest cities are located on its shores. Therefore, the most important shipping routes pass through the Atlantic. The ocean is called "the element that unites peoples."

Bottom relief The Atlantic Ocean, according to scientists, is the youngest and more leveled. The Mid-Atlantic Ridge stretches over 18,000 km from north to south of the ocean. Along the ridge there is a system of rifts, where the largest volcanic island, Iceland, was formed. Within the water area of ​​the Atlantic Ocean, depths of 3000-6000 m predominate. In contrast to the Pacific Ocean, there are few deep-sea trenches in the Atlantic Ocean. The deepest is Puerto Rico (8742 m) in the Caribbean Sea. The shelf zone is well defined within the ocean, especially in the Northern Hemisphere off the coast. North America and Europe.

climate of the atlantic ocean

The ocean is located in almost all geographic zones. This determined the diversity of its climate. In the north, in the region of the island of Iceland, an area of ​​low pressure is formed above the ocean, which is called the Icelandic Low. The prevailing winds over the ocean in tropical and subequatorial latitudes are trade winds, in temperate latitudes - westerly winds. Differences in atmospheric circulation are the cause of the uneven distribution of precipitation. (Refer to the Annual Precipitation Map for the distribution of precipitation in the Atlantic Ocean.) The average surface water temperature in the Atlantic Ocean is +16.5°C. The ocean has the most saline surface waters, with an average salinity of 35.4‰. The salinity of surface waters varies greatly in the north and south.

The maximum salinity reaches 36-37 ‰ and is typical for tropical regions with low annual precipitation and strong evaporation. The decrease in salinity in the north and south of the ocean (32-34 ‰) is explained by the melting of icebergs and floating sea ice.

currents in the atlantic ocean act as powerful carriers of thermal energy. Two systems of currents have formed in the ocean: clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. In the tropical latitudes of the ocean, the trade winds cause powerful surface currents from east to west on both sides of the equator - the North Trade Wind and South Trade Wind currents. Crossing the ocean, these currents have a warming effect on the eastern coasts of North and South America. The powerful warm Gulf Stream (“flow from the Gulf”) originates in the Gulf of Mexico and reaches the islands of Novaya Zemlya. The Gulf Stream carries 80 times more water than all the rivers in the world. The thickness of its flow reaches 700-800 m. This mass of warm water with a temperature of up to +28 ° C moves at a speed of about 10 km / h. North of 40° N. sh. The Gulf Stream turns towards the shores of Europe, and here it is called the North Atlantic Current. The temperature of the current water is higher than that of the ocean. Therefore, warmer and more humid air masses dominate the current and cyclones form. The Canary and Benguela currents have a cooling effect on the western coasts of Africa, and the cold Labrador Current on the east coast of North America. The eastern shores of South America are washed by the warm Brazilian Current.

The ocean is characterized by rhythmically repeating tides. The highest tidal wave in the world reaches 18 m off the coast of the Bay of Fundy.

Natural resources and environmental problems of the Atlantic Ocean

The Atlantic Ocean is rich in a variety of mineral resources. The largest oil and gas fields have been explored in the shelf zone off the coast of Europe (North Sea area), America (Gulf of Mexico, Maracaibo lagoon), etc. (Fig. 43). Phosphorite deposits are significant, ferromanganese nodules are less common.

Organic world of the Atlantic Ocean in terms of the number of species, it is poorer than the Pacific and Indian oceans, but has a higher productivity.

In the tropical part of the ocean, the greatest diversity of the organic world is noted, the number of fish species is measured in tens of thousands. These are tuna, mackerel, sardines. In temperate latitudes large quantities found herring, cod, haddock, halibut. Jellyfish, squids, octopuses are also inhabitants of the ocean. Large marine mammals (whales, pinnipeds), various types of fish (herring, cod), crustaceans live in cold waters. The main fish catch areas are the northeast off the coast of Europe and the northwest off the coast of North America. The wealth of the ocean is brown and red algae, kelp.

According to the degree of economic use, the Atlantic Ocean ranks first among other oceans. The use of the ocean plays an important role in the development of the economy of many countries of the world (Fig. 44).

The expanses of the Atlantic Ocean are most polluted with oil and oil products. Water purification is carried out by modern methods, the discharge of production waste is prohibited.

Features geographical location The Atlantic Ocean is its great elongation from north to south, the presence of inland and marginal seas. The Atlantic Ocean plays a leading role in the implementation of international economic relations. For five centuries, it has been ranked first in world shipping.

Atlantic Ocean- the second largest ocean after the Pacific Ocean. It contains 25% of the world's water. The average depth is 3,600 m. The maximum depth is in the Puerto Rico trench - 8,742 m. The ocean area is 91 million square meters. km.

general information

The ocean arose as a result of the split of the supercontinent Pangea» into two large parts, which subsequently formed into modern continents.

The Atlantic Ocean has been known to man since ancient times. Mentioning the ocean, which " called the Atlantic“, can be found in the records of the 3rd c. BC. The name probably originated from the legendary missing mainland " Atlantis«.

True, it is not clear what territory it designated, because in ancient times people were limited in their means of transportation by sea.

Relief and islands

A distinctive feature of the Atlantic Ocean is a very small number of islands, as well as a complex bottom topography, which forms many pits and gutters. The deepest among them are the Puerto Rico Trench and the South Sandwich Trench, which are over 8 km deep.

Earthquakes and volcanoes have a great influence on the structure of the bottom, the greatest activity of tectonic processes is observed in the equatorial zone.

Volcanic activity in the ocean has been going on for 90 million years. The height of many underwater volcanoes exceeds 5 km. The largest and most famous are found in the Puerto Rico and Yuno Sandwich trenches, as well as on the Mid-Atlantic Ridge.

Climate

The large meridional extent of the ocean from north to south explains the diversity of climatic conditions on the surface of the ocean. In the equatorial zone, there are slight temperature fluctuations throughout the year and an average of +27 degrees. The exchange of water with the Arctic Ocean also has a huge impact on ocean temperature. From the north, tens of thousands of icebergs drift into the Atlantic Ocean, reaching almost tropical waters.

The Gulf Stream, the largest current on the planet, is born off the southeastern coast of North America. Water consumption per day is 82 million cubic meters, which is 60 times higher than the flow of all rivers. The width of the current reaches 75 km. wide, and the depth is 700 m. The speed of the current varies between 6-30 km / h. The Gulf Stream carries warm waters, the temperature of the upper layer of the current is 26 degrees.

In the area of The Newfoundland Gulf Stream meets the cold wall of the Labrador Current. The mixing of waters creates ideal conditions for the reproduction of microorganisms in the upper layers. Best known in this regard Large Newfoundland barrel, which is a source of fishing for fish such as cod, herring and salmon.

Flora and fauna

The Atlantic Ocean is characterized by an abundance of biomass with a relatively poor species composition in the northern and southern margins. The greatest species diversity is observed in the equatorial zone.

Of the fish, the most common are the families of nanoteniy and white-blooded pikes. Large mammals are most widely represented: cetaceans, seals, fur seals, etc. The amount of plankton is insignificant, which causes whales to migrate to feeding areas to the north or to temperate latitudes, where it is more abundant.

Many places in the Atlantic Ocean have been and continue to be intensive fishing grounds. Early development of the ocean has led to the fact that hunting for mammals has been common here for a long time. This has reduced the number of some animal species compared to the Pacific and Indian Oceans.

Plants are represented by a wide range of green, brown and red algae. The famous sargasso form a popular book and interesting stories Sargasso Sea.