Oceans and their resources

Oil and gas deposits
1. Gas and oil form in the sea over a period of millions of years, as the remains of animals and plants sink to the ocean floor. Combined with particles flushed from the land, they are buried and compressed into layers of sediment several kilometres thick on the ocean floor
2. Today’s sources of fossil fuels are between 15 and 600 million years old. During this period the continental plates shifted, transforming oceans into landmasses, with the result that mineral deposits can be found both on land and at sea.
3. Oil and gas are usually found where vast layers of sediment cover the ocean floor.
Fishing
1. Fisheries of today provide about 16% of the total world's protein with higher percentages occurring in developing nations.
2. Due to the relative abundance of fish on the continental shelf, fisheries are usually marine and not freshwater.
3. The fish that are caught are not always used for food. In fact, about 40% of fish are used for other purposes such as fishmeal to feed fish grown in captivity.
4. The most common species making up the global fisheries are herring, cod, anchovy, flounder, tuna, shrimp, mullet, squid, crab, salmon, lobster, scallops and oyster
5. Most fish are only found in very specific habitats. Shrimp are fished in river deltas that bring large amounts of freshwater into the ocean. The areas of highest productivity known as banks are actually where the Continental Shelf extends outward towards the ocean
  1. These include the Georges Bank near Cape Cod, the Grand Banks near Newfoundland and Browns Bank
6. a world total of 86 million tons of fish were captured in 2000, China's fisheries were the most productive, capturing a whopping one third of the total
7. The amount of fish available in the oceans is an ever-changing number due to the effects of both natural causes and human developments. It will be necessary to manage ocean fisheries in the coming years to make sure the number of fish caught never makes it to zero
8. Water temperatures also influence the behavior of ecosystems, causing an increase in metabolism and predation or a sort of hibernation. Even the amount of turbulence in the water can affect predator-prey relationships, with more meetings between the two when waters are stirred up
Mining
1. Humans began to mine the ocean floor for diamonds, gold, silver, metal ores like manganese nodules and gravel mines in the 1950's when the company Tidal Diamonds was established by Sam Collins.
  1. Diamonds are found in greater number and quality in the ocean than on land, but are much harder to mine. When diamonds are mined, the ocean floor is dredged to bring it up to the boat and sift through the sediment for valuable gems.
2. The process is difficult as sediment is not easy to bring up to the surface, but will probably become a huge industry once technology evolves to solve the logistical problem
3. Metal compounds, gravels, sands and gas hydrates are also mined in the ocean.
  1. Mining of manganese nodules containing nickel, copper and cobalt began in the 1960's and soon after it was discovered that Papua New Guinea was one of the few places where nodules were located in shallow waters rather than deep waters.
4. Mining the ocean can be devastating to the natural ecosystems. Dredging of any kind pulls up the ocean floor resulting in widespread destruction of marine animal habitats, as well as wiping out vast numbers of fishes and invertebrates.
5. When the ocean floor is mined, a cloud of sediment rises up in the water, interfering with photosynthetic processes of phytoplankton and other marine life, in addition to introducing previously benign heavy metals into the food chain.
Oxygen Production
1. Gases in the atmosphere like carbon, nitrogen, sulfur and oxygen are dissolved through the water cycle
  1. crucial to all ecosystems and biological processes
2. originally came from the inside layers of the earth during the period when the earth was first formed.
3. The rate of flow for oxygen as well as other gases is controlled by biological processes, especially metabolism of organisms like prokaryotes and bacteria.
  1. Prokaryotes are able to use chemical energy to create organic matter and are capable of both reducing and oxidizing inorganic compounds
4. Bacteria that can reduce inorganic compounds are anaerobic and those that oxidize inorganic compounds are aerobic.
  1. Aerobic bacteria release oxygen as a by-product of photosynthesis

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	Creado por Valentin Bertiaux hace más de 8 años