[24], The MAR divides the Atlantic longitudinally into two-halves, in each of which a series of basins are delimited by secondary, transverse ridges. Currently, there is no cost-effective way to mine or extract gold from the ocean to make a profit. Similarly, the boundary dividing the Atlantic and Pacific oceans passes through the Drake Passage between Cape Horn at the tip of South America and the tip of the Antarctic Peninsula. Maximum temperatures occur north of the equator, and minimum values are found in the polar regions. [50], The break-up of Pangaea began in the Central Atlantic, between North America and Northwest Africa, where rift basins opened during the Late Triassic and Early Jurassic. It runs from 87°N or 300 km (190 mi) south of the North Pole to the subantarctic Bouvet Island at 54°S. Colonialism evolved as part of the Trans-Atlantic trade, but this trade also strengthened the position of merchant groups at the expense of monarchs. Off South Africa and Namibia deep-water hake and shallow-water Cape hake have recovered to sustainable levels since regulations were introduced in 2006 and the states of Southern African pilchard and anchovy have improved to fully fished in 2013. The information you enter will appear in your e-mail message and is not retained by Phys.org in any form. Studiul asupra viețuitoarelor mării arată că au nevoie de circa 20% oxigen și 80% apă pentru asigurarea unei vieți fără riscuri și pentru digerarea hranei. Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and Northern Africa. In the southeast, the Atlantic merges into the Indian Ocean. Dyke swarms in Brazil, Angola, eastern Paraguay, and Namibia, however, suggest the LIP originally covered a much larger area and also indicate failed rifts in all these areas. Fisheries have, however, undergone significant changes since the 1950s and global catches can now be divided into three groups of which only two are observed in the Atlantic: fisheries in the Eastern Central and South-West Atlantic oscillate around a globally stable value, the rest of the Atlantic is in overall decline following historical peaks. [43] The origin of the Sargasso fauna and flora remained enigmatic for centuries. Se consideră că Oceanul Atlantic este în continuă expansiune, iar Oceanul Pacific este în continuă micșorare. Due to a consistently strong wind shear and a weak Intertropical Convergence Zone, South Atlantic tropical cyclones are rare. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Hrana este necesară animalelor marine, doar când acestea își pierd energia vitală (stelele de mare, caii de mare, aricii de mare etc.). In the North-East Atlantic 21% of stocks are considered overfished. Author of numerous articles on oceanography. The most widely accepted limit between the South Atlantic and Indian oceans is a line that runs south from Cape Agulhas, at the southern tip of Africa, along the 20° E meridian to Antarctica. The slave trade was officially abolished in the British Empire and the United States in 1808, and slavery itself was abolished in the British Empire in 1838 and in the United States in 1865 after the Civil War. [77] This system of currents transport warm water into the North Atlantic, without which temperatures in the North Atlantic and Europe would plunge dramatically. } Climatic zones vary with latitude; the warmest zones stretch across the Atlantic north of the equator. East and west of the ridge, about 12,000 to 18,000 feet (3,700 to 5,500 metres) below sea level, lie basins that seem to present a relatively even profile, but parts of the basin floor are as mountainous as the Mid-Atlantic Ridge, while other parts are extremely smooth. [27], The MAR is intersected by two perpendicular ridges: the Azores–Gibraltar Transform Fault, the boundary between the Nubian and Eurasian plates, intersects the MAR at the Azores Triple Junction, on either side of the Azores microplate, near the 40°N. Insulele importante din Oceanul Atlantic sunt: Insulele Faroe, Svalbard, Groenlanda, Islanda, Rockall, Marea Britanie, Irlanda, Fernando de Noronha, Insulele Azore, Insulele Madeira, Insulele Canare, Insulele Capul Verde, São Tomé și Príncipe, Newfoundland, Bermuda, Indiile de Vest, Ascension, Sf. [57] The opening of the North Atlantic caused significant uplift of continental crust along the coast. Oceanic debris tends to accumulate at the center of gyres and coastlines, frequently washing aground where it is known as beach litter. The Atlantic is surrounded by passive margins except at a few locations where active margins form deep trenches: the Puerto Rico Trench (8,376 m or 27,480 ft maximum depth) in the western Atlantic and South Sandwich Trench (8,264 m or 27,113 ft) in the South Atlantic. [25], The MAR rises 2–3 km (1.2–1.9 mi) above the surrounding ocean floor and its rift valley is the divergent boundary between the North American and Eurasian plates in the North Atlantic and the South American and African plates in the South Atlantic. Acest fapt este unul grav, deoarece contribuie la dispariția multor specii aflate în pericol de extincție. By using our site, you acknowledge that you have read and understand our Privacy Policy There is even concern that northern Europe could be plunged into a deep freeze if the warm currents that normally head that way stop. You can unsubscribe at any time and we'll never share your details to third parties. The Lesser Antilles and the South Sandwich Islands form large unstable island arcs, where the greatest depths of the Atlantic are found in steep-sided, narrow gashes that drop to more than 25,000 feet (7,600 metres) below sea level and more than 10,000 feet (3,000 metres) below the floors of adjacent basins. For example, the Gulf Stream helps moderate winter temperatures along the coastline of southeastern North America, keeping it warmer in winter along the coast than inland areas. On the African east coast the small cyclonic Angola Gyre lies embedded in the large subtropical gyre. When temperatures are cool over the North Atlantic, a relatively low atmospheric pressure pattern is found over much of the Canadian High Arctic and Greenland. Surface water temperatures, which vary with latitude, current systems, and season and reflect the latitudinal distribution of solar energy, range from below −2 °C (28 °F) to over 30 °C (86 °F). [86], In 1497 John Cabot became the first Western European since the Vikings to explore mainland North America and one of his major discoveries was the abundant resources of Atlantic cod off Newfoundland. [55], Seafloor spreading led to the extension of the crust and formations of troughs and sedimentary basins. Although not the largest of the world’s oceans, the Atlantic has by far the largest drainage area. Medical Xpress covers all medical research advances and health news, Tech Xplore covers the latest engineering, electronics and technology advances, Science X Network offers the most comprehensive sci-tech news coverage on the web. A study published in the journal Science showed that some fish populations in the Atlantic have grown while others have shrunk in warming waters. [46], Climate is influenced by the temperatures of the surface waters and water currents as well as winds. [49], In many places, the continental shelf and continental slope are covered in thick sedimentary layers. Many other well-known species live in the Atlantic, from dolphins to sea turtles. Around 150 Ma sea-floor spreading propagated northward into the southern segment. Both quick-moving surface currents and slower-moving deep ocean currents circulate water around the globe. In contrast, 8–7 kya-old shell middens in Portugal, Denmark, and Brazil generated thousands of tons of debris and artefacts. [56]. Elena, Martin Vaz, Tristan da Cunha, Insulele Falkland și Insula Georgia de Sud. Meanwhile, the Scotia Arc and Caribbean Plate in the western Atlantic Basin are eastward-propagating subduction systems that might, together with the Gibraltar system, represent the beginning of the closure of the Atlantic Ocean and the final stage of the Atlantic Wilson cycle. Our editors will review what you’ve submitted and determine whether to revise the article.