The Bear Seamount is a

guyot In marine geology, a guyot (), also called 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 . Guyots are most commonly fo ...

or flat-topped underwater

volcano A volcano is commonly defined as a vent or fissure 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 oft ...

in the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

. 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 from the edge of Georges Bank. Many of th ...

, which was active more than 100 million years ago. It was formed when the North American Plate 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 White ...

. It is located inside the Northeast Canyons and Seamounts Marine National Monument, 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. The president directs the Federal government of the United States#Executive branch, executive branch of the Federal government of t ...

Barack Obama Barack Hussein Obama II (born August 4, 1961) is an American politician who was the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, he was the first African American president in American history. O ...

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 islan ...

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 southwestern corner of Cape Cod, near Martha's Vineyard and the Elizabeth Islands. The population was 78 ...

to north-east of

Bermuda Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest. Bermuda is an ...

. 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 is in the North Atlantic and has an area of around . It is located off the coast of the Canadian Maritime provinces and New England in the United States. The region was named for Rudolf von Willemoes-Suhm, a German naturali ...

. 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 is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida and up the eastern coastline of the United States, then veers east near 36°N latitude (North Carolin ...

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 ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

Biodiversity

Because little was known about the

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

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 ste ...

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 ''Coryphaenoides rupestris'' is a species of marine ray-finned fish in the family Macrouridae. Its common names include the rock grenadier, the roundnose grenadier and the roundhead rat-tail. In France it is known as ''grenadier de roche'' and in ...

'') 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 Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s were collected including squid such as ''

Mastigoteuthis agassizii ''Mastigoteuthis agassizii'' is a species of whip-lash squid. It is the type species of the genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant tax ...

'' 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 pigmen ...

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

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

such as the prawns '' Sergestes spp.'' and '' Acanthephyra 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 language, Greek word ''skyphos'' (), denoting a kind of drinking cup and ...

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