ARCTIC OCEAN

Speciality

The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions. The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions.The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea, classifying it a mediterranean sea or an estuary of the Atlantic Ocean. Alternatively, the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean.Almost completely surrounded by Eurasia and North America, the Arctic Ocean is partly covered by sea ice throughout the year[4] (and almost completely in winter). The Arctic Ocean's surface temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation, heavy fresh water inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of the ice has been quoted at 50%.The US National Snow and Ice Data Center (NSIDC) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years.

History

For much of European history, the north polar regions remained largely unexplored and their geography conjectural. Pytheas of Massilia recorded an account of a journey northward in 325 BC, to a land he called "Eschate Thule," where the Sun only set for three hours each day and the water was replaced by a congealed substance "on which one can neither walk nor sail." He was probably describing loose sea ice known today as "growlers" or "bergy bits;" his "Thule" was probably Norway, though the Faroe Islands or Shetland have also been suggested.Early cartographers were unsure whether to draw the region around the North Pole as land (as in Johannes Ruysch's map of 1507, or Gerardus Mercator's map of 1595) or water (as with Martin Waldseemüller's world map of 1507). The fervent desire of European merchants for a northern passage, the Northern Sea Route or the Northwest Passage, to "Cathay" (China) caused water to win out, and by 1723 mapmakers such as Johann Homann featured an extensive "Oceanus Septentrionalis" at the northern edge of their charts.The few expeditions to penetrate much beyond the Arctic Circle in this era added only small islands, such as Novaya Zemlya (11th century) and Spitsbergen (1596), though since these were often surrounded by pack-ice, their northern limits were not so clear. The makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank, with only fragments of known coastline sketched in.

This lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an "Open Polar Sea" was persistent. John Barrow, longtime Second Secretary of the British Admiralty, promoted exploration of the region from 1818 to 1845 in search of this.

Geography

The Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2 (5,427,000 sq mi), almost the size of Russia. The coastline is 45,390 km (28,200 mi) long.[9][11] It is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands.It is generally taken to include Baffin Bay, Barents Sea, Beaufort Sea, Chukchi Sea, East Siberian Sea, Greenland Sea, Hudson Bay, Hudson Strait, Kara Sea, Laptev Sea, White Sea and other tributary bodies of water. It is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea and Labrador Sea.Countries bordering the Arctic Ocean are: Russia, Norway, Iceland, Greenland, Canada and the United States.

ATLANTIC OCEAN

Speciality

The Atlantic Ocean is the world's second largest ocean, behind the Pacific Ocean. With a total area of about 106,400,000 square kilometres, it covers approximately 20 percent of the Earth's surface and about 29 percent of its water surface area. The Atlantic Ocean is the world's second largest ocean, behind the Pacific Ocean. With a total area of about 106,400,000 square kilometres (41,100,000 sq mi), it covers approximately 20 percent of the Earth's surface and about 29 percent of its water surface area. The first part of its name refers to Atlas of Greek mythology, making the Atlantic the "Sea of Atlas".The oldest known mention of "Atlantic" is in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Greek: Ἀτλαντὶς θάλασσα; English: Sea of Atlas). The term Ethiopic Ocean, derived from Ethiopia, was applied to the southern Atlantic as late as the mid-19th century. Before Europeans discovered other oceans, their term "ocean" was synonymous with the waters beyond the Strait of Gibraltar that are now known as the Atlantic. The early Greeks believed this ocean to be a gigantic river encircling the world.

Geography

The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. To the east, the boundaries of the ocean proper are Europe: the Strait of Gibraltar (where it connects with the Mediterranean Sea–one of its marginal seas–and, in turn, the Black Sea, both of which also touch upon Asia) and Africa.

In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. Some authorities show it extending south to Antarctica, while others show it bounded at the 60° parallel by the Southern Ocean.In the southwest, the Drake Passage connects it to the Pacific Ocean. The man-made Panama Canal links the Atlantic and Pacific. Besides those mentioned, other large bodies of water adjacent to the Atlantic are the Caribbean Sea, the Gulf of Mexico, Hudson Bay, the Arctic Ocean, the Mediterranean Sea, the North Sea, the Baltic Sea, and the Celtic Sea.Covering approximately 22% of Earth's surface, the Atlantic is second in size to the Pacific. With its adjacent seas, it occupies an area of about 106,400,000 square kilometres (41,100,000 sq mi); without them, it has an area of 82,400,000 square kilometres (31,800,000 sq mi). The land that drains into the Atlantic covers four times that of either the Pacific or Indian oceans. The volume of the Atlantic with its adjacent seas is 354,700,000 cubic kilometers (85,100,000 cu mi) and without them

Ocean floor

The principal feature of the bathymetry (bottom topography) is a submarine mountain range called the Mid-Atlantic Ridge.[6] It extends from Iceland in the north to approximately 58° South latitude, reaching a maximum width of about 860 nautical miles (1,590 km; 990 mi). A great rift valley also extends along the ridge over most of its length. The depth of water at the apex of the ridge is less than 2,700 metres (1,500 fathoms; 8,900 ft) in most places, while the bottom of the ridge is three times as deep. Several peaks rise above the water and form islands. The South Atlantic Ocean has an additional submarine ridge, the Walvis Ridge.The Mid-Atlantic Ridge separates the Atlantic Ocean into two large troughs with depths from 3,700–5,500 metres (2,000–3,000 fathoms; 12,100–18,000 ft). Transverse ridges running between the continents and the Mid-Atlantic Ridge divide the ocean floor into numerous basins. Some of the larger basins are the Blake, Guiana, North American, Cape Verde, and Canaries basins in the North Atlantic. The largest South Atlantic basins are the Angola, Cape,Argentina, and Brazil basins.The deep ocean floor is thought to be fairly flat with occasional deeps, abyssal plains, trenches, seamounts, basins, plateaus, canyons, and some guyots. Various shelves along the margins of the continents constitute about 11% of the bottom topography with few deep channels cut across the continental rise.

PACIFIC OCEAN

Speciality

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.25 million square kilometres (63.8 million square miles) in area, this largest division of the World Ocean – and, in turn, the hydrosphere – covers about 46% of the Earth's water surface and about one-third of its total surface area, making it larger than all of the Earth's land area combined. The equator subdivides it into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the Galápagos and Gilbert Islands, while straddling the equator, are deemed wholly within the South Pacific. The Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres (35,797 ft).[3]The eastern Pacific Ocean was first sighted by Europeans in the early 16th century when Spanish explorer Vasco Núñez de Balboa crossed the Isthmus of Panama in 1513 and discovered the great "southern sea" which he named Mar del Sur. The ocean's current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He therefore called it Mar Pacifico in Portuguese, meaning "peaceful sea.

History

Important human migrations occurred in the Pacific in prehistoric times. About 3000 BC speakers of the Austronesian languages, probably on the island of Taiwan, mastered the art of long-distance canoe travel and spread themselves, or their languages, south to the Philippines and Indonesia and east to the islands of Micronesia and Melanesia. The greatest migrations took place through the Polynesians, from the Asian edge of the ocean to Tahiti, Hawaii, New Zealand, Easter Island and possibly even America.

Long-distance trade developed all along the coast from Mozambique to Japan. Trade, and therefore knowledge, extended to the Indonesian islands but apparently not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of this trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality. From 1404 to 1433 Zheng He led expeditions into the Indian Ocean.

The Martin Waldseemüller map of 1507 was the first to show the Americas separating two distinct oceans.

The direct contact of the European fleets with western edges of the Pacific began with the Portuguese expeditions of António de Abreu and Francisco Serrão to the Maluku Islands in 1512, and with Jorge Álvares's expedition to southern China in 1513,both ordered by Afonso de Albuquerque. The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa. His expedition crossed the Isthmus of Panama and reached the Pacific Ocean in 1513.He named it Mar del Sur (literally, "Sea of the South", or South Sea).

Geography

The Pacific separates Asia and Australia from the Americas. It may be further subdivided by the equator into northern (North Pacific) and southern (South Pacific) portions. It extends from the Antarctic region in the South to the Arctic in the north. The Pacific Ocean encompasses approximately one-third of the Earth's surface, having an area of 165.2 million square kilometres (63.8 million square miles) —significantly larger than Earth's entire landmass of some 150 million square kilometres (58 million square miles

SOTHERN OCEAN

Speciality

The Southern Ocean (also known as the Great Southern Ocean, Antarctic Ocean, South Polar Ocean and Austral Ocean) comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. As such, it is regarded as the fourth-largest of the five principal oceanic divisions (after the Pacific, Atlantic, and Indian Oceans, but larger than the Arctic Ocean). This ocean zone is where cold, northward flowing waters from the Antarctic mix with warmer subantarctic waters.Geographers disagree on the Southern Ocean's northern boundary, and some even its existence—considering the waters part of the Pacific, Atlantic, and Indian Oceans instead. Others regard the Antarctic Convergence, an ocean zone which fluctuates seasonally, as separating the Southern Ocean from other oceans, rather than the 60th parallel.Australian authorities regard the Southern Ocean as lying immediately south of Australia.

History of exploration

Exploration of the Southern Ocean was inspired by a belief in the existence of a Terra Australis—a vast continent in the far south of the globe to "balance" the northern lands of Europe, Asia and North Africa—which had existed since the times ofPtolemy. The doubling of the Cape of Good Hope in 1487 by Bartolomeu Dias first brought explorers within touch of the Antarctic cold, and proved that there was an ocean separating Africa from any Antarctic land that might exist. Ferdinand Magellan, who passed through the Strait of Magellan in 1520, assumed that the islands of Tierra del Fuego to the south were an extension of this unknown southern land. In 1564, Abraham Ortelius published his first map, Typus Orbis Terrarum, an eight-leaved wall map of the world, on which he identified the Regio Patalis with Locach as a northward extension of the Terra Australis, reaching as far as New Guinea.

European geographers continued to connect the coast of Tierra del Fuego with the coast of New Guinea on their globes, and allowing their imaginations to run riot in the vast unknown spaces of the south Atlantic, south Indian and Pacific oceans they sketched the outlines of the Terra Australis Incognita ("Unknown Southern Land"), a vast continent stretching in parts into the tropics. The search for this great south land or Third World was a leading motive of explorers in the 16th and the early part of the 17th centuries.

South of the Antarctic Convergence

The visit to South Georgia by Anthony de la Roché in 1675 was the first ever discovery of land south of the Antarctic Convergence i.e. in the Southern Ocean / Antarctic. Soon after the voyage cartographers started to depict ‘Roché Island’, honouring the discoverer. James Cook was aware of la Roché's discovery when surveying and mapping the island in 1775.

Edmond Halley's voyage in HMS Paramour for magnetic investigations in the South Atlantic met the pack ice in 52° S in January 1700, but that latitude (he reached 140 mi off the north coast of South Georgia) was his farthest south. A determined effort on the part of the French naval officer Jean-Baptiste Charles Bouvet de Lozier to discover the "South Land" – described by a half legendary "sieur de Gonneyville" – resulted in the discovery of Bouvet Island in 54°10′ S, and in the navigation of 48° of longitude of ice-cumbered sea nearly in 55° S in 1730 .

In 1771, Yves Joseph Kerguelen sailed from France with instructions to proceed south from Mauritius in search of "a very large continent." He lighted upon a land in 50° S which he called South France, and believed to be the central mass of the southern continent. He was sent out again to complete the exploration of the new land, and found it to be only an inhospitable island which he renamed the Isle of Desolation, but which was ultimately named after him.

INDIAN OCEAN

Speciality

he Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded by Asia—including India, after which the ocean is named—on the north, on the west by Africa, on the east by Australia, and on the south by the Southern Ocean (or, depending on definition, by Antarctica).As one component of the World Ocean, the Indian Ocean is delineated from the Atlantic Ocean by the 20° east meridian running south from Cape Agulhas, and from the Pacific Ocean by the meridian of 146°55' east The northernmost extent of the Indian Ocean is approximately 30° north in the Persian Gulf. The ocean is nearly 10,000 km (6200 mi) wide at the southern tips of Africa and Australia, and its area is 73,556,000 km² (28,350,000 mi²), including the Red Sea and the Persian Gulf.The Indian Ocean's volume is estimated to be 292,131,000 km³ (70,086,000 mi³). Small islands dot the continental rims. Island nations within the ocean are Madagascar (the world's fourth largest island), Bahrain, Comoros, Maldives, Mauritius, Seychelles and Sri Lanka. The archipelago of Indonesia and the island nation of Timor-Leste border the ocean on the east. Geography
The African, Indian, and Antarctic crustal plates converge in the Indian Ocean at the Rodrigues Triple Point. Their junctures are marked by branches of the mid-oceanic ridge forming an inverted Y, with the stem running south from the edge of the continental shelf near Mumbai, India. The eastern, western, and southern basins thus formed are subdivided into smaller basins by ridges.The ocean's continental shelves are narrow, averaging 200 kilometres (125 mi) in width. An exception is found off Australia's western coast, where the shelf width exceeds 1,000 kilometres (600 mi). The average depth of the ocean is 3,890 m (12,762 ft). Its deepest point is Diamantina Deep in Diamantina Trench, at 8,047 m (26,401 ft) deep; also sometimes considered is Sunda Trench, at a depth of 7,258–7,725 m (23,812–25,344 ft).[10] North of 50° south latitude, 86% of the main basin is covered by pelagic sediments, of which more than half is globigerina ooze. The remaining 14% is layered with terrigenous sediments. Glacial outwash dominates the extreme southern latitudes. Hydrology
Among the few large rivers flowing into the Indian Ocean are the Zambezi, Shatt al-Arab, Indus, Narmada, Ganges, Brahmaputra, Jubba and Irrawaddy River. The ocean's currents are mainly controlled by the monsoon. Two large circular currents, one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise, constitute the dominant flow pattern. During the winter monsoon, however, currents in the north are reversed.Deep water circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, and Antarctic currents. North of 20° south latitude the minimum surface temperature is 22 °C (72 °F), exceeding 28 °C (82 °F) to the east. Southward of 40° south latitude, temperatures drop quickly.Surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and south-western Australia. Pack ice and icebergs are found throughout the year south of about 65° south lSSSatitude. The average northern limit of icebergs is 45° south latitude.

BEAUFORT SEA

Speciality

The Beaufort Sea is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, west of Canada's Arctic islands. The sea is named after hydrographer Sir Francis Beaufort.The Beaufort Sea (French: mer de Beaufort) is a marginal sea of the Arctic Ocean,[3] located north of the Northwest Territories, the Yukon, and Alaska, west of Canada's Arctic islands. The sea is named after hydrographer Sir Francis Beaufort. The major Mackenzie River empties into the Canadian part of the sea, west of Tuktoyaktuk, which is one of the few permanent settlements on the sea shores.The sea, characterized by severe climate, is frozen over most of the year. Historically, only a narrow pass up to 100 km (62 mi) opened in August–September near its shores, but recently due to climate change in the Arctic the ice-free area in late summer has greatly enlarged. The seacoast was populated about 30,000 years ago, but the population density is very low. The sea contains significant resources of petroleum and natural gas under its shelf, such as the Amauligak field. They were discovered in the period between the 1950s and 1980s, and their exploration became the major human activity in the area since the 1980s.

Geography

Several rivers such as the Kongakut River in Alaska and the Firth River in Yukon empty into the Beaufort. The major river to flow into the sea is the Mackenzie, Canada's longest, which empties into the Canadian part of the sea, west of Tuktoyaktuk. The coastal shelf area is rather narrow, especially near and east of Point Barrow in the Alaskan part of the sea, and contains numerous submarine valleys. It becomes wider near the delta of the Mackenzie River but nowhere exceeds 145 km (90 mi). Near the coast, the depths are shallower than 60 m (200 ft) but they rapidly increase northwards up to a few kilometers, transforming into a massive platform which is geologically similar to that of the oceans. There are many small islands in the sea and in the delta of the Mackenzie River. A few larger ones lie west of the Mackenzie River, such as Herschel Island (4 km (2.5 mi) off the shore, area 18 km2 (6.9 sq mi)) and Barter Island (0.3 km (0.19 mi) from the coast, area 13 km2 (5.0 sq mi)). The coasts are low, with the maximum elevations between 250 and 750 m (820 and 2,460 ft).[2] The soil is frozen all year around at the depth below about 1 m (3 ft 3 in) or less, forming permafrost, and only top few tens centimeters thaws in summer. Consequently, buildings have to be elevated above ground on wooden piles that are immersed into the permafrost.

Human activities

The Beaufort Sea coasts were populated about 30,000 years ago by migrating aboriginal peoples from Siberia. Later, around 9,000 years ago, they were replaced by Indians, 4,000 years ago by Paleo-Eskimos such as the Dorset culture, around 1,000 years ago by the Thule and finally by the modern Inuit. From early ages, they practised fishing – bones of Arctic char were found at the 4,000 years old settlements. While originally they lived nomadic life, later, they started to form permanent settlements. Modern Inuit are mostly concentrated near the Mackenzie River delta. Their population is increasing, but the unemployment rate is relatively highBowhead whales were hunted in the sea between 1888 and 1914. This practice stopped, first because of the decline in whale population and then because of government regulations, but resumed in the 1990s.The major settlements along the Beaufort Sea are Tuktoyaktuk (population 930 in 2009 in Canada and Prudhoe Bay, Alaska. Although Prudhoe Bay is permanently populated by only a few people, there are thousands of contract workers in the area employed on petroleum production at the Prudhoe Bay Oil Field, which is on the coastal lowland known as the North Slope. Artificial islands, such as Endicott and Northstar, have been raised near the shores in 1987 and 2001, respectively. The crude oil is transported through the Trans-Alaska Pipeline System to the southern port of Valdez

BARENTS SEA

Speciality

The Barents Sea is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents.The Barents Sea (Norwegian: Barentshavet; Russian: Баренцево море, Barentsevo More) is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents. It is a rather deep shelf sea (average depth 760 feet (230 m) and maximum depth 1,480 feet (450 m)), bordered by the shelf edge towards the Norwegian Sea in the west, the islands of Svalbard (Norway) in the northwest, and the islands of Franz Josef Land and Novaya Zemlya (Arkhangelsk Oblast) in the northeast and east. Novaya Zemlya separates the Kara Sea from the Barents Sea. Significant fossil fuel energy resources exist in the Barents Sea region.

Geography

The southern half of the Barents Sea, including the ports of Murmansk (Russia) and Vardø (Norway) remain ice-free year round due to the warm North Atlantic drift. In September, the entire Barents Sea is more or less completely ice-free. Until the Winter War (1939–40), Finland's territory also reached to the Barents Sea, with the harbor at Petsamo being Finland's only ice-free winter harbor.There are three main types of water masses in the Barents Sea: Warm, salty Atlantic water (temperature >3°C, salinity >35) from the North Atlantic drift, cold Arctic water (temperature <0°C, salinity <35) from the north, and warm, but not very salty coastal water (temperature >3°C, salinity <34.7). Between the Atlantic and Polar waters, a front called the Polar Front is formed. In the western parts of the sea (close to Bear Island), this front is determined by the bottom topography and is therefore relatively sharp and stable from year to year, while in the east (towards Novaya Zemlya), it can be quite diffuse and its position can vary a lot between years.

History

The Barents Sea was formerly known to Russians as Murmanskoye Morye, or the "Sea of Murmans" (i.e., Norwegians), and it appears with this name in sixteenth-century maps, including Gerard Mercator's Map of the Arctic published in his 1595 atlas. Its eastern corner, in the region of the Pechora River's estuary, has been known as Pechorskoye Morye, that is, Pechora Sea.This sea was given its present name in honor of Willem Barents, a Dutch navigator and explorer. Barents was the leader of early expeditions to the far north, at the end of the sixteenth century. Seabed mapping was completed in 1933 with the first full map produced by Russian marine geologist Maria Klenova.The Barents Sea was also the site of a notable World War II engagement, a German surface merchant raiding attack on a British convoy that later became known as the Battle of the Barents Sea. Under the command of Oskar Kummetz, the German warships sank minelayer HMS Bramble and destroyer HMS Achates (H12), but in turn lost destroyer Z16 Friedrich Eckoldt and Admiral Hipper was severely damaged by British gunfire. The Germans later retreated and the British convoy arrived safely at

BERING SEA

Speciality

The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves.The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves.The Bering Sea is separated from the Gulf of Alaska by the Alaska Peninsula. It covers over 2,000,000 square kilometres (770,000 sq mi) bordered on the east and northeast by Alaska, on the west by Russia's Far East and Kamchatka Peninsula, on the south by the Alaska Peninsula and the Aleutian Islands and on the far north by the Bering Strait, which connects the Bering Sea to the Arctic Ocean's Chukchi Sea. Bristol Bay is the portion of the Bering Sea which separates the Alaska Peninsula from mainland Alaska. The Bering Sea is named for Vitus Bering, a Danish navigator in Russian service, who in 1728 was the first European to systematically explore it, sailing from the Pacific Ocean northward to the Arctic Ocean

.

History

Most scientists believe that during the most recent ice age, sea level was low enough to allow humans and other animals to migrate on foot from Asia to North America across what is now the Bering Strait. This is commonly referred to as the "Bering land bridge" and is believed by some—though not all— to be the first point of entry of humans into the Americas.There is a small portion of the Kula Plate in the Bering Sea. The Kula Plate is an ancient tectonic plate that used to subduct under Alaska during the Triassic period.

Geography

On the South. A line running from Kabuch Point (54°48′N 163°21′W) in the Alaskan Peninsula, through the Aleutian Islands to the South extremes of the Komandorski Islands and on to Cape Kamchatka in such a way that all the narrow waters between Alaska and Kamchatka are included in the Bering Sea.The Bering Sea shelf break is the dominant driver of primary productivity in the Bering Sea. This zone, where the shallower continental shelf drops off into the North Aleutians Basin is also known as the “Greenbelt”. Nutrient upwelling from the cold waters of the Aleutian basin flowing up the slope and mixing with shallower waters of the shelf provide for constant production of phytoplankto.

Ecosystem

The second driver of productivity in the Bering Sea is seasonal sea ice that, in part, triggers the spring phytoplankton bloom. Seasonal melting of sea ice causes an influx of lower salinity water into the middle and other shelf areas, causing stratification and hydrographic effects which influence productivity. In addition to the hydrographic and productivity influence of melting sea ice, the ice itself also provides an attachment substrate for the growth of algae as well as interstitial ice algae.

LRISH SEA

Speciality

The Irish Sea separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel.The Irish Sea (Irish: Muir Éireann, Manx: Y Keayn Yernagh, Scots: Erse Sea, Scottish Gaelic: Muir Èireann, Ulster-Scots: Airish Sea, Welsh: Môr Iwerddon) separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man. The sea is occasionally, but rarely, referred to as the Manx Sea (Irish: Muir Meann Manx: Mooir Vannin, Scottish Gaelic: Muir Mhanainn).The sea is of significant economic importance to regional trade, shipping and transport, fishing, and power generation in the form of wind power and nuclear plants. Annual traffic between Great Britain and Ireland amounts to over 12 million passengers and 17 million tonnes of traded goods.

Geography

The most accessible and possibly the greatest wildlife resource of the Irish Sea lies in its estuaries: particularly the Dee Estuary, the Mersey Estuary, the Ribble Estuary, Morecambe Bay, the Solway Firth, Loch Ryan, the Firth of Clyde, Belfast Lough, Strangford Lough, Carlingford Lough, Dundalk Bay, Dublin Bay and Wexford Harbour. However, a lot of wildlife also depends on the cliffs, salt marshes and sand dunes of the adjoining shores, the seabed and the open sea itself.The information on the invertebrates of the seabed of the Irish Sea is rather patchy because it is difficult to survey such a large area, where underwater visibility is often poor and information often depends upon looking at material brought up from the seabed in mechanical grabs. However, the groupings of animals present depend to a large extent on whether the seabed is composed of rock, boulders, gravel, sand, mud or even peat. In the soft sediments seven types of community have been

Radioactivity

The Irish Sea has been described by Greenpeace as the most radioactively contaminated sea in the world with some "eight million litres of nuclear waste" discharged into it each day from Sellafield reprocessing plants, contaminating seawater, sediments and marine life.Low-level radioactive waste has been discharged into the Irish Sea as part of operations at Sellafield since 1952. The rate of discharge began to accelerate in the mid- to late 1960s, reaching a peak in the 1970s and generally declining significantly since then. As an example of this profile, discharges of plutonium (specifically 241Pu) peaked in 1973 at 2,755TBq falling to 8.1 TBq by 2004. Improvements in the treatment of waste in 1985 and 1994 resulted in further reductions in radioactive waste discharge although the subsequent processing of a backlog resulted in increased discharges of certain types of radioactive waste. Discharges of technetium in particular rose from 6.1 TBq in 1993 to a peak of 192TBq in 1995 before dropping back to 14TBq in 2004. In total 22PBq of 241Pu was discharged over the period 1952 to 1998. Current rates of discharge for many radionuclides are at least 100 times lower than they were in the 1970s.

ADRIATIC SEA

speciality

The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula and the Apennine Mountains from the Dinaric Alps and adjacent ranges.The Adriatic Sea /ˌeɪdriˈætɨk/ (Albanian: Deti Adriatik; Croatian: Jadransko more; Istro-Romanian: marea Adriatică; Italian: mare Adriatico; Slovene: Jadransko morje) is a body of water separating the Italian Peninsula from the Balkan peninsula and the Apennine Mountains from the Dinaric Alps and adjacent ranges. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to the northwest and the Po Valley. The countries with coasts on the Adriatic are Italy, Croatia, Albania, Montenegro, Bosnia-Herzegovina, and Slovenia. The Adriatic contains over 1,300 islands, mostly located along its eastern, Croatian, coast. It is divided into three basins, the northern being the shallowest and the southern being the deepest, with a maximum depth of 1,233 metres (4,045 ft). The Otranto Sill, an underwater ridge, is located at the border between the Adriatic and Ionian Seas. The prevailing currents flow counterclockwise from the Strait of Otranto, along the eastern coast and back to the strait along the western (Italian) coast. Tidal movements in the Adriatic are slight, although larger amplitudes are known to occur occasionally. The Adriatic's salinity is lower than the Mediterranean's because the Adriatic collects a third of the fresh water flowing into the Mediterranean, acting as a dilution basin. The surface water temperatures generally range from 24 °C (75 °F) in summer to 12 °C (54 °F) in winter, significantly moderating the Adriatic Basin's climate.

Geography

The Adriatic Sea is a semi-enclosed sea bordered in the southwest by the Apennine or Italian Peninsula, in the northwest by the Italian regions of Veneto and Friuli-Venezia Giulia, and in the northeast by Slovenia, Croatia, Bosnia-Herzegovina, Montenegro, and Albania—the Balkan peninsula. In the southeast, the Adriatic Sea connects to the Ionian Sea at the 72-kilometre (45 mi) wide Strait of Otranto. The International Hydrographic Organization (IHO) defines the boundary between the Adriatic and the Ionian seas as a line running from the Butrinto River's mouth (latitude 39°44'N) in Albania to the Karagol Cape in Corfu, through this island to the Kephali Cape (these two capes are in latitude 39°45'N), and on to the Santa Maria di Leuca Cape (latitude 39°48'N) It extends 800 kilometres (500 mi) from the northwest to the southeast and is 200 kilometres (120 mi) wide. It covers 138,600 square kilometres (53,500 sq mi) and has a volume of 35,000 cubic kilometres (8,400 cu mi). The Adriatic extends northwest from 40° to 45°47' north, representing the Mediterranean's northernmost portion.

Geology

Geophysical and geological information indicate that the Adriatic Sea and the Po Valley are associated with a tectonic microplate—identified as the Apulian or Adriatic Plate—that separated from the African Plate during the Mesozoic era. This separation began in the Middle and Late Triassic, when limestone began to be deposited in the area. Between the Norian and Late Cretaceous, the Adriatic and Apulia Carbonate Platforms formed as a thick series of carbonate sediments (dolomites and limestones), up to 8,000 metres (26,000 ft) deep. Remnants of the former are found in the Adriatic Sea, as well as in the southern Alps and the Dinaric Alps, and remnants of the latter are seen as the Gargano Promontory and the Maiella mountain. In the Eocene and early Oligocene, the plate moved north and north-east, contributing to the Alpine orogeny (along with the African and Eurasian Plates' movements) via the tectonic uplift of the Dinarides and Alps. In the Late Oligocene, the motion was reversed and the Apennine Mountains' orogeny took place.

CARIBBEAN SEA

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The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by the Yucatán Peninsula of Mexico and Central America to the west and southwest, to the ...The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by the Yucatán Peninsula of Mexico and Central America to the west and southwest, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the north coast of South America.The entire area of the Caribbean Sea, the numerous islands of the West Indies, and adjacent coasts, are collectively known as the Caribbean. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km² (1,063,000 sq. mi.). The sea's deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m (25,220 ft) below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria and Gulf of Honduras.

History

The name "Caribbean" is derived from the Caribs, one of the dominant Native American groups in the region at the time of European contact during the late 15th century. After the discovery of the West Indies by Christopher Columbus in 1492, the Spanish term Antillas was assigned to the lands; stemming from this, "Sea of the Antilles" is a common alternative name for the Caribbean Sea in various European languages. During the first century of development, the Spanish dominance was The Caribbean Sea was an unknown body of water to the populations of Eurasia until 1492, when Christopher Columbus first sailed into Caribbean waters on a quest to find a sea route to Asia. At that time the Western Hemisphere in general was unknown to Europeans. Following the discovery of the islands by Columbus, the area was quickly colonised by several Western cultures (initially Spain, then later Portugal, England, the Dutch Republic, France and Denmark). Following the colonisation of the Caribbean islands, the Caribbean Sea became a busy area for European-based undisputed.

Geology

The Caribbean Sea is an oceanic sea largely situated on the Caribbean Plate. The Caribbean Sea is separated from the ocean by several island arcs of various ages. The youngest of them stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad and Tobago off the coast of Venezuela. This arc was formed by the collision of the South American Plate with the Caribbean Plate and includes active and extinct volcanoes such as Mount Pelee, the Quill (volcano) on Sint Eustatius in the Caribbean Netherlands and Morne Trois Pitons on Dominica. The larger islands in the northern part of the sea Cuba, Haiti, Jamaica and Puerto Rico lie on an older island arc. The geological age of the Caribbean Sea is not known with certainty but is estimated to have an age between 160 and 180 million years and was formed by a horizontal fracture that split the supercontinent called Pangea in the Mesozoic Era. It is assumed that the proto-caribbean basin existed in the Devonian period. In the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size. 

NORTH SEA

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The North Sea is a marginal sea of the Atlantic Ocean located between Great Britain, Scandinavia, Germany, the Netherlands, Belgium, and FranceThe North Sea is a marginal sea of the Atlantic Ocean located between Great Britain, Scandinavia Germany, the Netherlands, Belgium, and France. An epeiric (or "shelf") sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north. It is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, with an area of around 750,000 square kilometres (290,000 sq mi).Historically, the North Sea has featured prominently in geopolitical and military affairs, particularly in Northern Europe but also globally through the power northern Europeans projected worldwide during much of the Middle Ages and into the modern era. The North Sea was the centre of the Vikings' rise. Subsequently, the Hanseatic League, the Netherlands, and the British each sought to dominate the North Sea and thus the access to the markets and resources of the world. As Germany's only outlet to the ocean, the North Sea continued to be strategically important through both World Wars.

Geography

The North Sea is bounded by the Orkney Islands and east coast of Great Britain to the west and the northern and central European mainland to the east and south, including Norway, Denmark, Germany, the Netherlands, Belgium, and France. In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively.In the north it is bordered by the Shetland Islands, and connects with the Norwegian Sea, which lies in the very north-eastern part of the Atlantic.

Natural history

Copepods and other zooplankton are plentiful in the North Sea. These tiny organisms are crucial elements of the food chain supporting many species of fish. Over 230 species of fish live in the North Sea. Cod, haddock, whiting, saithe, plaice, sole, mackerel, herring, pouting, sprat, and sandeel are all very common and are fished commercially.Due to the various depths of the North Sea trenches and differences in salinity, temperature, and water movement, some fish such as blue-mouth redfish and rabbitfish reside only in small areas of the North Sea.Crustaceans are also commonly found throughout the sea. Norway lobster, deep-water prawns, and brown shrimp are all commercially fished, but other species of lobster, shrimp, oyster, mussels and clams all live in the North Sea. Recently non-indigenous species have become established including the Pacific oyster and Atlantic jackknife clam.

History

Through history various names have been used for the North Sea. One of the earliest recorded names was Septentrionalis Oceanus, or "Northern Ocean," which was cited by Pliny. The name "North Sea" probably came into English, however, via the Dutch "Noordzee", who named it thus either in contrast with the Zuiderzee ("South Sea"), located south of Frisia, or simply because the sea is generally to the north of the Netherlands. Before the adoption of "North Sea," the names used in English were "German Sea" or "German Ocean", the latter referred to the Latin name "Oceanus Germanicus" and they persisted even into the 1830s

BLACK SEA

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The Black Sea is a sea in Southeastern Europe. It is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean Seas and various straits.The Black Sea is a sea in Southeastern Europe. It is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean Seas and various straits. The Bosphorus Strait connects it to the Sea of Marmara, and the Strait of the Dardanelles connects that sea to the Aegean Sea region of the Mediterranean. These waters separate eastern Europe and western Asia. The Black Sea is also connected to the Sea of Azov by the Strait of Kerch.The Black Sea has an area of 436,400 km2 (168,500 sq mi) (not including the Sea of Azov)a maximum depth of 2,212 m (7,257 ft),[2] and a volume of 547,000 km3 (131,000 cu mi).The Black Sea forms in an east-west trending elliptical depression which lies between Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine.It is constrained by the Pontic Mountains to the south and by the Caucasus Mountains to the east, and features a wide shelf to the northwest. The longest east-west extent is about 1,175 km (730 mi).

Geology and bathymetry

The geological origins of the basin can be traced back to two distinct relict back-arc basins which were initiated by the splitting of an Albian volcanic arc and the subduction of both the Paleo- and Neo-Tethys Oceans, but the timings of these events remain controversial. Since its initiation, compressional tectonic environments led to subsidence in the basin, interspersed with extensional phases resulting in large-scale volcanism and numerous orogenies, causing the uplift of the Greater Caucasus, Pontides, Southern Crimean Peninsula and Balkanides mountain ranges.

Hydrology

The Black Sea is a marginal sea and is the world’s largest body of water with a meromictic basin. The deep waters do not mix with the upper layers of water that receive oxygen from the atmosphere. As a result, over 90% of the deeper Black Sea volume is anoxic water. The Black Sea’s circulation patterns are primarily controlled by basin topography and fluvial inputs, which result in a strongly stratified vertical structure. Because of the extreme stratification, it is classified as a salt wedge estuary.

ARABIAN SEA

Speciality

The Arabian Sea is a region of the northern Indian Ocean bounded on the north by Pakistan and Iran, on the southwest by northeastern Somalia, on the east by India, and on the west by the Arabian PeninsulThe Arabian Sea is a region of the northern Indian Ocean bounded on the north by Pakistan and Iran, on the southwest by northeastern Somalia, on the east by India, and on the west by the Arabian Peninsula. Some of the ancient names of this body of water include Sindhu Sagar meaning "Sea of Sindh" in Sanskrit and Erythraean Sea.

Description

The Arabian Sea's surface area is about 3,862,000 km2 (1,491,130 sq mi).The maximum width of the Sea is approximately 2,400 km (1,490 mi), and its maximum depth is 4,652 metres (15,262 ft). The biggest river flowing into the Sea is the Indus River.The Arabian Sea has two important branches — the Gulf of Aden in the southwest, connecting with the Red Sea through the strait of Bab-el-Mandeb; and the Gulf of Oman to the northwest, connecting with the Persian Gulf. There are also the gulfs of Cambay and Kutch on the Indian coast.The countries with coastlines on the Arabian Sea are Somalia, Djibouti, Yemen, Oman, Iran, Pakistan, India and the Maldives. There are several large cities on the sea's coast including Karachi, Gwadar, Pasni, Ormara, Aden, Muscat, Mumbai, Keti Bandar, Salalah, Duqm and Kochi.

Trade routes

The Arabian Sea has been an important marine trade route since the era of the coastal sailing vessels from possibly as early as the 3rd millennium BCE, certainly the late 2nd millennium BCE through the later days known as the Age of Sail. By the time of Julius Caesar, several well-established combined land-sea trade routes depended upon water transport through the Sea around the rough inland terrain features to its north.These routes usually began in the Far East or down river from Madhya Pradesh with transshipment via historic Bharuch (Bharakuccha), traversed past the inhospitable coast of today's Iran then split around Hadhramaut into two streams north into the Gulf of Aden and thence into the Levant, or south into Alexandria via Red Sea ports such as Axum. Each major route involved transhipping to pack animal caravan, travel through desert country and risk of bandits and extortionate tolls by local potentiates.

RED SEA

Speciality

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez leading to the Suez Canal. The Red Sea is a Global 200 ecoregion. The sea is underlain by the Red Sea Rift which is part of the Great Rift Valley.he ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden.The Red Sea has a surface area of roughly 438,000 km (169,100 mi. It is about 2250 km (1398 mi) long and, at its widest point, 355 km (220.6 mi) wide. It has a maximum depth of 2211 m (7254 ft) in the central median trench, and an average depth of 490 m (1,608 ft). However, there are also extensive shallow shelves, noted for their marine life and corals. The sea is the habitat of over 1,000 invertebrate species, and 200 soft and hard corals. It is the world's northernmost tropical sea.

History

The earliest known exploration of the Red Sea was conducted by ancient Egyptians, as they attempted to establish commercial routes to Punt. One such expedition took place around 2500 BC, and another around 1500 BC ( by Hatshepsut. Both involved long voyages down the Red Sea. The Biblical Book of Exodus tells the story of the Israelites' crossing of a body of water, which the Hebrew text calls Yam Suph. Yam Suph was traditionally identified as the Red Sea. The account is part of the Israelites' escape from slavery in Egypt. Yam Suph can also been translated as Sea of Reeds.In the 6th century BC, Darius the Great of Persia sent reconnaissance missions to the Red Sea, improving and extending navigation by locating many hazardous rocks and currents. A canal was built between the Nile and the northern end of the Red Sea at Suez. In the late 4th century BC, Alexander the Great sent Greek naval expeditions down the Red Sea to the Indian Ocean.

Living resources

The Red Sea is a rich and diverse ecosystem. More than 1200 species of fish have been recorded in the Red Sea, and around 10% of these are found nowhere else. This also includes 42 species of deepwater fish.Red Sea coral and marine fishThe rich diversity is in part due to the 2,000 km (1,240 mi) of coral reef extending along its coastline; these fringing reefs are 5000–7000 years old and are largely formed of stony acropora and porites corals. The reefs form platforms and sometimes lagoons along the coast and occasional other features such as cylinders such as the Blue Hole (Red Sea) at Dahab). These coastal reefs are also visited by pelagic species of red sea fish, including some of the 44 species of shark.The Red Sea also contains many offshore reefs including several true atolls. Many of the unusual offshore reef formations defy classic (i.e., Darwinian) coral reef classification schemes, and are generally attributed to the high levels of tectonic activity that characterize the area.The special biodiversity of the area is recognized by the Egyptian government, who set up the Ras Mohammed National Park in 1983. The rules and regulations governing this area protect local marine life, which has become a major draw for diving enthusiasts.