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Deep sea communities are groups of organisms associated by a shared habitat in the deep sea. They remain largely unexplored, due to the technological and logistical challenges and expense involved in visiting these remote biomes. Because of the unique challenges (particularly the high barometric pressure, extremes of temperature and absence of light), it was long believed that little life existed in this hostile environment. Since the 19th century however, research has demonstrated that significant biodiversity exists in the deep sea. The three main sources of energy and nutrients for deep sea communities are marine snow, whale falls, and chemosynthesis at hydrothermal vents and cold seeps. ==History== Prior to the 19th century scientists assumed life was sparse in the deep ocean. In the 1870s Sir Charles Thompson and colleagues aboard the Challenger expedition discovered many deep-sea creatures of widely varying types. The first discovery of any deep-sea chemosynthetic community including higher animals was unexpectedly made at hydrothermal vents in the eastern Pacific Ocean during geological explorations (Corliss et al., 1979).〔Minerals Management Service Gulf of Mexico OCS Region (November 2006). "Gulf of Mexico OCS Oil and Gas Lease Sales: 2007–2012. Western Planning Area Sales 204, 207, 210, 215, and 218. Central Planning Area Sales 205, 206, 208, 213, 216, and 222. Draft Environmental Impact Statement. Volume I: Chapters 1–8 and Appendices". U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans. page 3-27. (PDF )〕 Two scientists, J. Corliss and J. van Andel, first witnessed dense chemosynthetic clam beds from the submersible ''DSV Alvin'' on February 17, 1977, after their unanticipated discovery using a remote camera sled two days before.〔 The Challenger Deep is the deepest surveyed point of all of Earth's oceans; it is located at the southern end of the Mariana Trench near the Mariana Islands group. The depression is named after HMS ''Challenger'', whose researchers made the first recordings of its depth on 23 March 1875 at (station 225 ). The reported depth was 4,475 fathoms (8184 meters) based on two separate soundings. In 1960, Don Walsh and Jacques Piccard descended to the bottom of the Challenger Deep in the ''Trieste'' bathyscaphe. At this great depth a small flounder-like fish was seen moving away from the spotlight of the bathyscaphe. The Japanese remote operated vehicle (ROV) ''Kaiko'' became the second vessel to reach the bottom of the Challenger Deep in March 1995. ''Nereus'', a hybrid remotely operated vehicle (HROV) of the Woods Hole Oceanographic Institution, is the only vehicle capable of exploring ocean depths beyond 7000 meters. ''Nereus'' reached a depth of 10,902 meters at the Challenger Deep on May 31, 2009. On 1 June 2009, sonar mapping of the Challenger Deep by the Simrad EM120 multibeam sonar bathymetry system aboard the R/V ''Kilo Moana'' indicated a maximum depth of . The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth (this is an error of about 22 meters at this depth).〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Deep sea communities」の詳細全文を読む スポンサード リンク
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