OCEANS and the WORLD

Do we know enough of Oceans? What is this enigma that oceans present? Man has landed on the moon, sent spacecrafts to the edge of the solar system, but he is yet to fully understand the form and dynamics of the oceans. Do we know enough?

Ocean Titbits 362,000,000 km2 or 71% of the surface of the globe is water. The oceans contain 1,300,000,000 km3 (328,000,000 miles3) of water. The average depth is 4 km. The Mariana Trench is the deepest spot at 11.7 km. It contains 97 % of our planet's free water. The other 3 % is found in atmosphere or on and in land in various forms and stores. There are 300 to 500 million species of organisms in the ocean, yet these vast resources are largely unexplored. The Ocean's biological wealth is concentrated along a relatively narrow strip formed by continental shelves, coastal margins and estuaries. These contain the major fishing grounds, yielding more than 80% of the world's fishing catch. Here, too, are the world's most productive and diverse habitats: mangroves, saltmarches, mudflats, seagrass and seaweed beds, and coral reefs. Globally, seafood represents one-fifth of animal protein and 5 percent of the total protein in the human diet. Global fish production exceeds that of cattle, sheep, poultry or eggs. It is the biggest source of wild or domestic protein in the world. But 15 of the world's 17 largest fisheries are either overfished or in trouble. Any big weather event, such as a hurricane, typhoon, flood or drought, is generated by ocean conditions. Major climate events, such as El Nio, result from ocean temperature changes. El Nio refers to abnormally warm ocean surface temperatures and changing wind patterns, which changes weather around the globe. Atlantic Ocean The Atlantic Ocean is considered a passive margin ocean with most of its geological activity centered along the Mid-Atlantic Ridge. Most of its coastal regions are low and geologically quiet. The Atlantics major marginal seas include the Mediterranean Sea, the North Sea, the Baltic Sea, Hudson Bay, the Gulf of Mexico, and the Caribbean Sea. The Atlantic covers an area of 82 million square kilometers (32 million square miles). It has an average depth of 3,600 meters (11,812 feet). Its greatest depth is in the Puerto Rico Trench at 8,605 meters (28,231 feet). Some of the current issues include endangered marine species include the manatee, seals, sea lions, turtles, and whales; driftnet fishing is exacerbating declining fish stocks and contributing to international disputes; municipal sludge pollution off eastern U.S., southern Brazil, and eastern Argentina; oil pollution in Caribbean Sea, Gulf of Mexico, Lake Maracaibo, Mediterranean Sea, and North Sea; industrial waste and municipal sewage pollution in Baltic Sea, North Sea, and Mediterranean Sea Indian Ocean The smallest of the three major oceans, the Indian Ocean covers an area of about 73 million square kilometers (about 28 million square miles) - about 20 percent of the total area covered by the world's oceans. The average depth of the Indian Ocean is 3,890 meters (12,762 feet). Its deepest point is the Java trench, at 7,725 m. Some of the current issues include endangered marine species include the dugong, seals, turtles, and whales; oil pollution in the Arabian Sea, Persian Gulf, and Red Sea

Pacific Ocean The world's largest geographic feature, the Pacific Ocean covers more than 166 million square kilometers (more than 64 million square miles)about one-third of the earth's surface. The area of the Pacific is greater than that of all of the continents combined, and it makes up nearly half of the area covered by the earth's oceans. Some of the current issues include endangered marine species include the dugong, sea lion, sea otter, seals, turtles, and whales; oil pollution in Philippine Sea and South China Sea Southern Ocean The Southern Ocean, designated as such in 2000, is a body of water that lies between 60 degrees south latitude and the Antarctica coastline. It's coordinates nominally are 65 00 S, 0 00 E, but the Southern Ocean has the unique distinction of being a large circumpolar body of water totally encircling the continent of Antarctica. This ring of water lies between 60 degrees south latitude and the coast of Antarctica, and encompasses 360 degrees of longitude. The Southern Ocean is now the fourth largest of the world's five oceans (after the Pacific Ocean, Atlantic Ocean, and Indian Ocean, but larger than the Arctic Ocean). Some of the current issues include impacts of global warming, ocean currents, environment and climate change research, fisheries Oceanic Divisions

DIVISION OF OCEAN Oceanographers divide the ocean into different ZONES depending on the present physical and biological conditions. The PELAGIC ZONE includes all open ocean regions, and can be divided into further regions categorized by depth and light abundance. The PHOTIC ZONE covers the oceans from surface level to 200 metres down. This is the region where photosynthesis can occur and therefore is the most BIODIVERSE. Since plants require photosynthesis, life found deeper than this must either rely on material sinking from above or find another energy source; HYDROTHERMAL VENTS are the primary option in what is known as the APHOTIC ZONE (depths exceeding 200 m). The pelagic part of the photic zone is known as the EPIPELAGIC. The pelagic part of the aphotic zone can be further divided into regions that succeed each other vertically according to temperature. The mesopelagic is the uppermost region. Its lowermost boundary is at a thermocline of 12 C (54 F), which, in the tropics generally lies at 7001,000 meters (2,3003,300 ft). Next is the bathypelagic lying between 10 and 4 C (50 and 39 F), typically between 7001,000 meters (2,3003,300 ft) and 2,0004,000 metres (6,60013,000 ft) Lying along the top of the abyssal plain is the abyssalpelagic, whose lower boundary lies at about 6,000 metres (20,000 ft).

 The last zone includes the deep trenches, and is known as the hadalpelagic. This lies between 6,000 11,000 meters (20,00036,000 ft) and is the deepest oceanic zone. Along with pelagic aphotic zones there are also benthic aphotic zones. These correspond to the three deepest zones of the deep-sea. The bathyal zone covers the continental slope down to about 4,000 metres (13,000 ft). The abyssal zone covers the abyssal plains between 4,000 and 6,000 m. Lastly, the hadal zone corresponds to the hadalpelagic zone which is found in the oceanic trenches. The pelagic zone can also be split into two subregions, the neritic zone and the oceanic zone. The neritic encompasses the water mass directly above the continental shelves, while the oceanic zone includes all the completely open water. Biology The ocean has a significant effect on the biosphere. Oceanic evaporation, as a phase of the water cycle, is the source of most rainfall, and ocean temperatures determine climate and wind patterns that affect life on land. Life within the ocean evolved 3 billion years prior to life on land. Both the depth and the distance from shore strongly influence the biodiversity of the plants and animals present in each region. Lifeforms native to the ocean include: Fish; Radiata, such as jellyfish (Cnidaria); Cetacea, such as whales, dolphins, and porpoises; Cephalopods, such as octopus and squid; Crustaceans, such as lobsters, clams, shrimp, and krill; Marine worms; Plankton; and Echinoderms, such as brittle stars, starfish, sea cucumbers, and sand dollars. Exploration Ocean travel by boat dates back to prehistoric times, but only in modern times has extensive underwater travel become possible. The deepest point in the ocean is the Mariana Trench, located in the Pacific Ocean near the Northern Mariana Islands. Its maximum depth has been estimated to be 10,971 metres (35,994 ft) (plus or minus 11 meters; see the Mariana Trench article for discussion of the various estimates of the maximum depth.) The British naval vessel, Challenger II surveyed the trench in 1951 and named the deepest part of the trench, the "Challenger Deep". In 1960, the Trieste successfully reached the bottom of the trench, manned by a crew of two men. Much of the ocean bottom remains unexplored and unmapped. Trieste The Trieste is a Swiss-designed, Italian-built deep-diving research bathyscaphe ("deep boat") with a crew of two, which reached a record maximum depth of about 10,911 metres (35,797 ft), in the deepest known part of the Earth's oceans, the Challenger Deep, in the Mariana Trench near Guam, on 23 January 1960, crewed by Jacques Piccard (son of the boat's designer Auguste Piccard) and U.S. Navy Lieutenant Don Walsh achieving the goal of Project Nekton.