Bransfield Strait or Fleet Sea ( es, Estrecho de Bransfield, Mar de la Flota) is a body of water about wide extending for in a general northeast – southwest direction between the

South Shetland Islands The South Shetland Islands are a group of Antarctic islands with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the nearest point of the South Orkney Islands. By the Antarctic Treaty of 195 ...

and the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...

History

The strait was named in about 1825 by

James Weddell James Weddell (24 August 1787 – 9 September 1834) was a British sailor, navigator and seal hunter who in February 1823 sailed to latitude of 74° 15′ S—a record 7.69 degrees or 532 statute miles south of the Antarct ...

, Master,

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...

, for

Edward Bransfield Edward Bransfield (c. 1785 – 31 October 1852) was an Irish sailor who became an officer in the British Royal Navy, serving as a master on several ships, after being impressed into service in Ireland at the age of 18. He is noted for his par ...

, Master, RN, who charted the South Shetland Islands in 1820. It is called ''Mar de la Flota'' by

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. On 23 November 2007, the MS ''Explorer'' struck an

iceberg An iceberg is a piece of freshwater ice more than 15 m long that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. Smaller chunks of floating glacially-derived ice are called "growlers" or "bergy bits". The ...

and sank in the strait; all 154 passengers were rescued and no injuries were reported.

Description

The undersea

trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...

through the strait is known as Bransfield Trough (). The basin is about 400 km long and 2 km deep, between the South Shetland Island Arc and the Antarctic Peninsula. It was formed by

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

ing behind the islands, which began about 4 million years ago. Ongoing rifting has caused recent earthquakes and volcanism. The Strait hosts a chain of submerged

seamount A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abru ...

s of volcanic origin, including the presently inactive

Orca Seamount Orca Seamount is a seamount (underwater volcano) near King George Island in Antarctica, in the Bransfield Strait. While it is inactive, last volcanic activity at Orca Seamount is judged to have occurred in the recent past as there are temperatu ...

.Hatzky, Jörn (2005): The Orca Seamount Region, Antarctica (Sect. 5.5.2). In: Peter C. Wille (ed.), Sound Images of the Ocean in Research and Monitoring, Springer-Verlag Berlin. However last volcanic activity at Orca Seamount is judged to have occurred in the recent past as there are temperature anomalies in the seawater around the seamount.

Thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...

and hyperthermophilic microorganisms have been found at the seamount. Thermophiles found on the seafloor outside Orca Seamount may indicate that thermal waters of Orca Seamount may travel laterally through geological structures or that currents bring in thermal water from

Deception Island Deception Island is an island in the South Shetland Islands close to the Antarctic Peninsula with a large and usually "safe" natural harbor, which is occasionally troubled by the underlying active volcano. This island is the caldera of an act ...

, an active volcano.

Geographic features

Nomad Rock is an isolated rock in the strait, off the north coast of

Trinity Peninsula Trinity Peninsula is the northernmost part of the Antarctic Peninsula. It extends northeastward for about 130 km (80 mi) to Cape Dubouzet from an imaginary line connecting Cape Kater on the north-west coast and Cape Longing on the sou ...

and northeast of

Cape Legoupil Cape Legoupil is a cape at the northeast side of the entrance to Huon Bay, Trinity Peninsula, Antarctica, terminating in Schmidt Peninsula. It was discovered by a French expedition under Captain Jules Dumont d'Urville, 1837–40, and named for ar ...

. So named by

United Kingdom Antarctic Place-Names Committee The UK Antarctic Place-Names Committee (or UK-APC) is a United Kingdom government committee, part of the Foreign and Commonwealth Office, responsible for recommending names of geographical locations within the British Antarctic Territory (BAT) and ...

(UK-APC) because of confusion about the identity of geographic points along this coast, and because of the wandering of features and names on charts of this vicinity. The Zélée Rocks are a group of rocks, some of which are above water and others near the surface, lying in Bransfield Strait north of

Prime Head A prime number (or a prime) is a natural number greater than 1 that is not a Product (mathematics), product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime ...

, the north tip of

. They were discovered by the French expedition of 1837–40, under Captain

Jules Dumont d'Urville Jules Sébastien César Dumont d'Urville (; 23 May 1790 – 8 May 1842) was a French explorer and naval officer who explored the south and western Pacific, Australia, New Zealand, and Antarctica. As a botanist and cartographer, he gave his nam ...

, and named by him after one of the expedition's ships, the

corvette A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper (or " rated") warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the slo ...

''Zélée''.

Antarctic Specially Protected Area

An area of relatively shallow marine waters of about 1021 km², off the western and southern coasts of

Low Island Geologically, a low island is an island of coral origin. The term applies whether the island was formed as a result of sedimentation upon a coral reef or of the uplifting of such islands. The term is used to distinguish such islands from high ...

, has been designated an

Antarctic Specially Protected Area An Antarctic Specially Protected Area (ASPA) is an area on the continent of Antarctica, or on nearby islands, which is protected by scientists and several different international bodies. The protected areas were established in 1961 under the Antarct ...

(ASPA 152) because it is one of only two known sites near the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

’s

Palmer Station Palmer Station is a United States research station in Antarctica located on Anvers Island, the only US station located north of the Antarctic Circle. Initial construction of the station finished in 1968. The station, like the other U.S. Antarcti ...

suitable for

bottom trawling Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towin ...

for fish and other benthic organisms. Fish have been collected from the site by scientists from Palmer Station since the early 1970s, and it is recognised as an important

spawning ground Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

for several species, including Black Rockcod and Blackfin Icefish.

References

External links

Bathymetric map of the Bransfield Straight, Antarctic Peninsula, showing zone of active rifting and volcanism
{{Coord, 63, S, 59, W, source:GNIS, display=title Straits of Graham Land Landforms of Trinity Peninsula Antarctic Specially Protected Areas