The Bear Seamount is a

guyot In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed .volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

. It is the oldest of the

New England Seamounts The New England Seamounts is a chain of over twenty underwater extinct volcanic mountains known as seamounts. This chain is located off the coast of Massachusetts in the Atlantic Ocean and extends over 1,000 km from the edge of Georges Ban ...

, which was active more than 100 million years ago. It was formed when the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

moved over the

New England hotspot The New England hotspot, also referred to as the Great Meteor hotspot and sometimes the Monteregian hotspot, is a volcanic hotspot in the North Atlantic Ocean. It created the Monteregian Hills intrusions in Montreal and Montérégie, the Whit ...

. It is located inside the

Northeast Canyons and Seamounts Marine National Monument The Northeast Canyons and Seamounts Marine National Monument is a marine national monument of the United States off the coast of New England, on the seaward edge of Georges Bank. It was created by President Barack Obama on September 15, 2016, a ...

, which was proclaimed by

President of the United States The president of the United States (POTUS) is the head of state and head of government of the United States of America. The president directs the executive branch of the federal government and is the commander-in-chief of the United Stat ...

Barack Obama Barack Hussein Obama II ( ; born August 4, 1961) is an American politician who served as the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, Obama was the first African-American president of the U ...

to protect the seamount's biodiversity.

Formation

The Bear Seamount is the first guyot in a chain of about 30 extinct volcanoes extending in a straight line south-eastwards from the edge of the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

near

Woods Hole, Massachusetts Woods Hole is a census-designated place in the town of Falmouth in Barnstable County, Massachusetts, United States. It lies at the extreme southwest corner of Cape Cod, near Martha's Vineyard and the Elizabeth Islands. The population was 781 ...

to north-east of

Bermuda ) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , e ...

. These seamounts resulted from the movement of a mantle plume hotspot. This hotspot is now under the

Great Meteor Seamount The Great Meteor Seamount, also called the Great Meteor Tablemount, is a guyot and the largest seamount in the North Atlantic with a volume of . It is one of the Seewarte Seamounts, rooted on a large terrace located south of the Azores Plateau. Th ...

. The chain rises about above the surrounding

Sohm Abyssal Plain The Sohm Abyssal Plain An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% o ...

. Over time they have been eroded and have developed flat table-like summits surrounded by slopes with an inclination of about 20°. The currents in the vicinity of the Bear Seamount include the warm water

Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Current, North Atlantic Drift, is a warm and swift Atlantic Ocean, Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida a ...

flowing towards the north east, the deep

boundary current Boundary currents are ocean currents with dynamics determined by the presence of a coastline, and fall into two distinct categories: western boundary currents and eastern boundary currents. Eastern boundary currents Eastern boundary currents are ...

flowing along the continental shelf towards the south west, and the deep, icy cold Arctic bottom water that flows past the lower flanks of the chain. Bear Seamount rises approximately above the surrounding seabed and the roughly flat summit is about below the surface of the sea. The top is covered by a deep layer of sediment through which basaltic rocks and erratic boulders protrude. Much of this material has fallen from above, probably from icebergs that drifted southwards during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

Biodiversity

Because little was known about the

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...

of the New England Seamount Chain, an expedition was mounted in 2000. The NOAA

National Marine Fisheries Service The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the stew ...

deep water research vessel R/V Delaware II made 20 exploratory trawls in the vicinity of Bear Seamount and around 274 species were collected. These included 115 species of fish, some of which were rare or had not been recorded in the western North Atlantic before. The roundnose grenadier ('' Coryphaenoides rupestris'') and the onion-eye grenadier ('' Macrourus berglax'') were the only fish species of potential commercial importance – they were caught in mid-water at depths of between and were up to a metre in length. A common but much smaller fish was '' Aldrovandia phalacra''. Twenty-six species of

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s were collected including squid such as '' Mastigoteuthis agassizii'' and ''

Mastigoteuthis magna ''Mastigoteuthis magna'' is a species of whip-lash squid, characterised by a lack of photophores. The skin is heavily pigmented a deep red by a numerous chromatophore Chromatophores are cells that produce color, of which many types are pigment- ...

''. Other invertebrates caught by trawls dragged along the seamount surface included 46 species of

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

such as the prawns '' Sergestes spp.'' and ''

Acanthephyra ''Acanthephyra'' is a genus of shrimp in the family Acanthephyridae, with species that live at depths from 0 to more than 5000 meters deep below the ocean surface. Species * '' Acanthephyra acanthitelsonis'' Spence Bate, 1888 * '' Acanthephyr ...

spp.'', and the shrimp '' Pasiphaea spp''. Also present was the bank-forming deepwater coral '' Lophelia pertusa'', which supported a community of worms, hydroids and other corals. Brittle stars, especially '' Ophiomusium lymani'', were numerous as were the sea urchin '' Echinus affinis'', the sea star '' Neomorphaster forcipatus'',

mysid Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in thi ...

s and various

scyphozoan The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or "true jellies"). The class name Scyphozoa comes from the Greek word ''skyphos'' (), denoting a kind of drinking cup and alluding to the ...

Notes and references

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External links

NOAA: Animated fly-through of the Bear Seamount
Guyots Seamounts of the Atlantic Ocean Landforms of the Atlantic Ocean Polygenetic volcanoes Cretaceous volcanoes