[89], The pelagic zone contains macro- and microfauna and myriad zooplankton which drift with the currents. Battles have been fought on the sea for more than 3,000 years. Earth Science, Geography, Oceanography, Physical Geography. ", "The Seas: Our Knowledge of Life in the Sea and How It is Gained", "Drinking seawater can be deadly to humans", "Density and Absolute Salinity of the Baltic Sea 20062009", Drinking Seawater Can Be Deadly to Humans, "Were extreme waves in the Rockall Trough the largest ever recorded? Their commercial extraction for nickel was investigated in the 1970s but abandoned in favour of more convenient sources. [52] A rip current can occur when water piles up near the shore from advancing waves and is funnelled out to sea through a channel in the seabed. SEA, Ltd. experts specialize in forensic consulting services and failure analysis, litigation support, consumer product testing, and vehicle testing & safety. Article 87(1) (a) to (f) gives a non-exhaustive list of freedoms including navigation, overflight, the laying of submarine cables, building artificial islands, fishing and scientific research. In the tropics, with the sun nearly overhead, the temperature of the surface layers can rise to over 30C (86F) while near the poles the temperature in equilibrium with the sea ice is about 2C (28F). A wide variety of organisms, including bacteria, protists, algae, plants, fungi, and animals, lives in the sea, which offers a wide range of marine habitats and ecosystems, ranging vertically from the sunlit surface and shoreline to the great depths and pressures of the cold, dark abyssal zone, and in latitude from the cold waters under polar ice caps to the warm waters of coral reefs in tropical regions. [3]:1213 In 1519 the Portuguese navigator Ferdinand Magellan led the Spanish Magellan-Elcano expedition which would be the first to sail around the world. The marine nitrogen cycle consists of complex microbial transformations which include the fixation of nitrogen, its assimilation, nitrification, anammox and denitrification. Sea definition, the salt waters that cover the greater part of the earth's surface. Recreational divers restrict themselves to depths of 100 feet (30m) beyond which the danger of nitrogen narcosis increases. According to this definition, the Caspian would be excluded as it is legally an "international lake". A sea can be more than 2.6 million square kilometers (1 million square miles) in area, such as the Caribbean Sea. Scientists differ as to precisely where in the sea life arose: the Miller-Urey experiments suggested a dilute chemical "soup" in open water, but more recent suggestions include volcanic hot springs, fine-grained clay sediments, or deep-sea "black smoker" vents, all of which would have provided protection from damaging ultraviolet radiation which was not blocked by the early Earth's atmosphere. SEA offers a variety of programs with focuses on science, environmental issues, culture and history. Sometimes it is there just as a gentle background but often it introduces such themes as storm, shipwreck, battle, hardship, disaster, the dashing of hopes and death. [190], Several nomadic indigenous groups in Maritime Southeast Asia live in boats and derive nearly all they need from the sea. [223] In the centre of the Pacific gyre there is a permanent floating accumulation of mostly plastic waste[224] and there is a similar garbage patch in the Atlantic. Thousands of new images every day Completely Free to Use High-quality videos and images from Pexels. Over 60 percent of the world's container traffic is conveyed on the top twenty trade routes. She was part of the crew aboard the exploration vessel Nautilus, a ship that shared its scientific discoveries in the Mediterranean Sea, the Black Sea, and elsewhere with students around the world in online lessons and chats. Text on this page is printable and can be used according to our Terms of Service. In 1905, the Japanese fleet decisively defeated the Russian fleet, which had travelled over 18,000 nautical miles (33,000km), at the Battle of Tsushima. In about 1210 B.C., Suppiluliuma II, the king of the Hittites, defeated and burned a fleet from Alashiya (modern Cyprus). [180], Seafloor massive sulphide deposits are potential sources of silver, gold, copper, lead and zinc and trace metals since their discovery in the 1960s. Not only does this cause waves to form but it also makes the surface seawater move in the same direction as the wind. In daylight the photosynthetic activity of these plants produces oxygen, which dissolves in the seawater and is used by marine animals. The seven seas has been used to describe the worlds great water bodies for a long time. This map was used in 1492 when Christopher Columbus set out on his voyages of discovery. The Italian Amerigo Vespucci, after whom America was named, explored the South American coastline in voyages made between 1497 and 1502, discovering the mouth of the Amazon River. The difference in height between the high tide and low tide is known as the tidal range or tidal amplitude. Here the coastal nation has the exclusive right to harvest minerals and also living resources "attached" to the seabed. ", "Mariculture, Environmental, Economic and Social Impacts of", "The voice of the recreational marine industry worldwide", "Offshore Energy Clash Over Undersea Sound", "Effects of offshore drilling: energy vs. environment", 10.1002/(SICI)1099-1085(200001)14:1<145::AID-HYP916>3.0.CO;2-N, "Environmental, social and cultural settings of the Surin Islands", "Marine Mammal Harvests and Other Interactions with Humans", "Traditional Owners of the Great Barrier Reef", "Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms", "Why Corals Care About Ocean Acidification: Uncovering the Mechanism", "Warming up, turning sour, losing breath: Ocean biogeochemistry under global change", "Bioaccumulation of heavy metals in some commercially important fishes from a tropical river estuary suggests higher potential health risk in children than adults", "Accumulation and fragmentation of plastic debris in global environments", "Huge Garbage Patch Found in Atlantic too", "How Does the BP Oil Spill Impact Wildlife and Habitat? [200], The sea and ships have been depicted in art ranging from simple drawings on the walls of huts in Lamu[196] to seascapes by Joseph Turner. A major trade route passes through the Pillars of Hercules, across the Mediterranean and the Suez Canal to the Indian Ocean and through the Straits of Malacca; much trade also passes through the English Channel. [144] Shipping lanes are the routes on the open sea used by cargo vessels, traditionally making use of trade winds and currents. [3]:15 Wyville Thompson became chief scientist on the Challenger expedition of 18721876, which effectively created the science of oceanography. [3]:1213, As for the history of navigational instrument, a compass was first used by the ancient Greeks and Chinese to show where north lies and the direction in which the ship is heading. The friction between air and water caused by a gentle breeze on a pond causes ripples to form. [64], The zone where land meets sea is known as the coast and the part between the lowest spring tides and the upper limit reached by splashing waves is the shore. "Territorial waters" extend to 12nautical miles (22kilometres; 14miles) from the coastline and in these waters, the coastal state is free to set laws, regulate use and exploit any resource. [61] In mid-ocean, magma is constantly being thrust through the seabed between adjoining plates to form mid-oceanic ridges and here convection currents within the mantle tend to drive the two plates apart. [27] Evaporation and by-product of ice formation (known as "brine rejection") increase salinity, whereas precipitation, sea ice melt, and runoff from land reduce it. The sea is the interconnected system of all the Earth's oceanic waters, including the Atlantic, Pacific, Indian, Southern and Arctic Oceans. SEA is provided by the Shoichet Laboratory in the Department of Pharmaceutical Chemistry at the University of California, San Francisco (UCSF). The latter is composed of relatively dense basalt and is some five to ten kilometres (three to six miles) thick. [21] Marine biology (biological oceanography) studies the plants, animals, and other organisms inhabiting marine ecosystems. Material worn from the margins of the land eventually ends up in the sea. These break into small pieces and coalesce into flat discs that form a thick suspension known as frazil. Tides, the generally twice-daily rise and fall of sea levels, are caused by Earth's rotation and the gravitational effects of the Moon and, to a lesser extent, of the Sun. ocean. Deep-sea currents, known as the global conveyor belt, carry cold water from near the poles to every ocean. Many of the major groups of organisms evolved in the sea and life may have started there. The potential energy of the displaced seawater is turned into kinetic energy, creating a shallow wave, a tsunami, radiating outwards at a velocity proportional to the square root of the depth of the water and which therefore travels much faster in the open ocean than on a continental shelf. Since sunlight illuminates only the upper layers, the major part of the ocean exists in permanent darkness. This tiny Turkish sea connects the Aegean Sea and the Black Sea. [102] Around 500 BC, the Carthaginian navigator Hanno left a detailed periplus of an Atlantic journey that reached at least Senegal and possibly Mount Cameroon. [90] The zooplankton feed on phytoplankton and on each other and form a basic part of the complex food chain that extends through variously sized fish and other nektonic organisms to large squid, sharks, porpoises, dolphins and whales. [45][46], The top of a wave is known as the crest, the lowest point between waves is the trough and the distance between the crests is the wavelength. Overexploitation has become a serious concern; it does not only cause the depletion of fish stocks, but also substantially reduce the size of predatory fish populations. The sea has been an integral element for humans throughout history and culture. However, the word "sea" can also be used for many specific, much smaller bodies of seawater, such as the North Sea or the Red Sea.There is no sharp distinction between seas and oceans, though generally seas are smaller, and are often [33] Ocean deoxygenation is projected to increase hypoxia by 10%, and triple suboxic waters (oxygen concentrations 98% less than the mean surface concentrations), for each 1C of upper ocean warming. Our mission is to better the lives of consumers and small businesses with technology. [210][211][212] The pH is expected to reach 7.7 (representing a 3-fold increase in hydrogen ion concentration) by the year 2100, which is a significant change in a century. Corals often contain photosynthetic symbionts and live in shallow waters where light penetrates. The size of the waves depends on the fetch, the distance that the wind has blown over the water and the strength and duration of that wind. [141] From the 16th to the 19th centuries, over a period of 400 years, about 1213million Africans were shipped across the Atlantic to be sold as slaves in the Americas as part of the Atlantic slave trade. Text on this page is printable and can be used according to our Terms of Service investigated... Twenty trade routes and microfauna and myriad zooplankton which drift with the.. 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