Earth Science: Oceans – Deep Sea
Today, the deep sea is one of the least researched parts of our planet. Only during the last few decades have researchers had access to the technical means to reach the darkness of the deep oceans.
Biologically, the deep sea begins at a depth of about 650 feet (200 m) where the water is no longer subject to surface wind and heat variations and where photo- synthesis is impossible due to the lack of sufficient light. The completely dark zone, however, only begins at a depth of about 3,280 feet (1,000 m).
Humans cannot survive at such depths as the pressure is around 100 times that at sea level. The water temperature at this depth is constantly below 39.2°F (4°C).
Life in the dark
Organisms living in the deep sea have adapted to the high pressure by storing water in their bodies, some consisting almost entirely of water. Most deep-sea organisms lack gas bladders. They are cold- blooded organisms that adjust their body temperature to their environment, allowing them to survive in the cold water while maintaining a low metabolism.
Many species lower their metabolism so much that they are able to survive without food for long periods of time, as finding the sparse food that is available expends a lot of energy. Many predatory fish of the deep sea are equipped with enormous mouths and sharp teeth, allowing them to hold on to prey and overpower it. Some predators hunting in the residual light zone of the ocean have excellent visual capabilities, while others are able to create their own light (bioluminescence) to attract prey or a mating partner.
Habitats near underwater hot springs require very special adaptations for organisms to survive. Many invertebrate species have mastered these unique conditions and survive on sulfur bacteria. Black smokers, a type of hydrothermal vent, were discovered in 1977 near the Galapagos Islands by the manned submersible Alvin.
Trips to the unknown
The first trip into the deep sea was made by the Americans William Beebe and Otis Bartin in 1934. They used a diving chamber called a bathysphere that was lowered to a depth of about 2,950 feet (900 m).
The American Don Walsh and the Swiss Jacques Piccard set a world record in 1960 with the Trieste; they managed to reach the bottom of the Mariana Trench at a depth of 35,813 feet (10,916 m). Nowadays, there are many unmanned submersibles that explore the deep sea, forwarding data to surface research ships.
NATURAL RESOURCES OF THE DEEP SEA
While the extraction of mineral ore such as gold, platinum, tin, and titanium in the deep seas may still be an exceptional endeavor, recent efforts are being put into exploring the potential of manganese nodules In the Pacific Ocean, a large enough source of manganese, iron, copper, nickel, and cobalt exists to satisfy the demands of industry for this century
Another very promising source of energy is frozen gas occurring in the form of methane hydrate; however, extraction of these energy sources is not only extremely challenging, but may also pose substantial threats to the global climate.