Bellingshausen Abyssal Plain
Gosztonyia antarctica, discovered in 2003 at 650 m in depth above the Bellingshausen Abyssal Plan.
The Bellingshausen Abyssal Plain is one of four deepwater plains that comprise the deepwater Antarctic Basin (the others being the Amundsen, Enderby, and the South Indian Abyssal Plains). It is located at around 90-120 degrees W. This is one of the locations of the formation of deep cold water masses in the Antarctic region. The maximum depth of this deepwater feature is 5181 meters.
Situated beyond the uncharacteristically wide continental shelf of the Bellingshausen Sea, this Bathypelagic zone is an example of inverted temperature, where the sea surface is colder than the deepwater mass. Nonetheless, this plain is considered a volume of formation of cold deepwater mass, which drives deep ocean currents northward as part of the thermohaline circulation of the global ocean system.
Above the Bellingshausen Abyssmal Plain surface circulation on the Bellingshausen Sea is dominated by the eastward-flowing wind driven Antarctic Circumpolar Current, whose chief convection is slightly to the north of the Bellingshausen Basin. A counterflow deep current is presented, wherein modified deep water from the Waddell Basin enters the deeper Bellingshausen Sea.
Contents
The Bellingshausen Abyssmal Plain is a very deep hydrographic feature of the Bellingshausen Basin.
The continental shelf along the margin of the Bellingshausen Sea is wide compared to most of the Antarctic fringe, except for that along the neighboring Amundsen Sea.
This shelf is commonly 220 to 320 kilometers (km) wide, but occasionally may extend to 400 km. The shelf is riddled with numerous glacial grooves and extensive deposits of submarine sediments at the shelf edge. The depth at the shelf edges is moderately deep, approximating 500 meters; furthermore, like the Amundsen Sea, there is less upwelling at shelf edge than for other seas of the Southern Ocean.
Source: Demis
Sea ice forms in gradual degrees in an annual cycle, and sea ice melt occurs relatively slowly as well, unlike the rapid melt seen in most of the Antarctic Zone. This slow sea ice melt is thought to be associated with the relatively low salinity and relative lack of deep water influence seen both in the Amundsen and Bellingshausen Basins.
Chemistry and ecology
Less is known about the chemistry and environment of the Bellingshausen Abyssal Plain than the sea layers above. The capacity of the Bellingshausen Basin as a whole to act as a carbon dioxide sink is very high, based upon very large carbon uptake from the atmosphere in summer. This uptake is likely due to enhanced seasonal biological activity, and Riffenburgh suggests that this sea may have further potential to serve as as massive carbon sink.
Bathypelagic zone fishes found in the Bellingshausen Sea include Lepidonotothen kempi, a midwater species found here at the southern limit of its distribution; another bathypelagic fish is the deepwater smelt Bathylagus antarcticus. Mesopelagic zone species found in this basin are the lanternfishes Protomyctophum bolini and Gymnoscopelus opisthopterus.
Corresponding to the paucity of nutrients, the Bellingshausen Sea is depauperate of zooplankton and also higher faunal forms including cetaceans and seabirds relative to other Antarctic seas. Classic ice edge algal blooms are generally not seen in the Bellingshausen Sea. Furthermore, low levels of dissolved iron are limiting to phytoplankton production. A number of cetaceans graze the krill within the Bellingshausen Sea, including the Minke whale and Humpback whale.
The Antarctic silverfish, Pleuragramma antarcticum, is a prominent Epipelagic zone midwater fish that spawns on coastal shelves in the Bellingshausen Basin, its larvae being transported in by the Antarctic Circumpolar Current..
The slight warming trend of the last century is favorable for a number of organisms, especially penguins such as the Gentoo and Chinstrap. Future benefits are expected to accrue to benthic shelf biota, which will be able to colonize more effectively without the excessive ice gouging of the shelf floor.
Further reading
- Ranier Gersonde, F.T.Kyte, T.Frederichs, U.Bleil, H.-W.Schenke, G.Kuhn and T.Frank. 2005. The late Pliocene impact of the Eltanin asteroid into the Southern Ocean – Documentation and environmental consequences. Geophysical Research Abstracts 7. 1607-7962/gra/EGU05-A-02449
- Rhodes W.Fairbridge, editor. The Encyclopedia of Oceanography. Van Nostrand Reinhold Co., 1966.
- A.S.Grotov, D.A.Nechaev, G.G.Panteleev and M.I.Yaremchuk. Large–scale circulation in the Bellingshausen and Amundsen seas as a variational inverse of climatological data. JGR, 103:13,011–13,022, 1998.
- David McGonigal. 2009. Antarctica: Secrets of the Southern Continent. frances lincoln ltd. 400 pages
- Beau Riffenburgh. 2007. Encyclopedia of the Antarctic, Volume 1. CRC Press. 1272 pages
- Robin M.Ross, Eileen Elizabeth Hofmann, Langdon B.Quetin. 1996. Foundations for ecological research West of the Antarctic Peninsula. American Geophysical Union. 448 pages
- Peter Saundry. 2011. Seas of the world. Topic ed. C.Michael Hogan. Ed.-in-chief Cutler J.Cleveland. Encyclopedia of Earth. Washington DC
- D.R.Turner and N.J.P.Owens. 1995. A biogeochemical study in the Bellingshausen Sea: Overview of the STERNA 1992 expedition. DSR II, 42:907–932.
