Vents in the deep sea

English name: Vents in the deep sea

Quick facts

EUNIS habitat type code A6.94

Description (English)

Hydrothermal vents occur along spreading ridges (such as the mid-Atlantic ridge), subduction zones, fracture zones and back-arc basins (Gage & Tyler, 1991), and are caused by seawater penetrating the upper levels of the Earth’s crust through channels formed in cooling lava flows, reacting chemically with hot basalt in the Earth’s crust and then rising back to the sea-bed to vent as superheated water containing compounds such as sulphides, metals, CO2 and methane (Tunnicliffe et al, 1998 in Gubbay, 2002). The water may trickle out from cracks and crevices on the seabed as hot springs (5-250°C), or as very concentrated jets of superheated water (270-380°C). As these concentrated jets of water cool, minerals dissolved in the water precipitate out in black clouds, giving them their common name of ‘black smokers’. At lower temperatures, sulphides are mostly precipitated within the rocks, making the venting fluids appear cloudier. These are known as ‘white smokers’ (Gage & Tyler, 1991). Hydrothermal vent fields cover relatively small areas of the seabed in water depths of 850 - 4000 m. The biological communities associated with hydrothermal vents are unusual as they are able to derive energy under conditions where photosynthesis is not possible. These habitats contain a huge diversity of chemoautotrophic bacteria, which form the core of the trophic structure around the vent. Characteristic species include the giant vent clam Calyptogena magnifica, the mussel Bathymodiolus thermophilus, the tube worm Riftia pachyptila, the crabs Cyanograea praedator and Bythograea thermydron and the shrimp Charocaris fortunate.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Not available

Other classifications

Classification Code Habitat type name Relationship type
Palaearctic Habitat Classification 200112 11.215 Hydrothermal benthic communities same
CORINE Land Cover 5.2.3. Sea and ocean n/a
For relation to plant communities (syntaxa), see Vegetation types

History

Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200410 A6.94 Vents in the deep sea same
EUNIS Habitat Classification 200202 A6.5 Vents in the deep sea same
EUNIS Habitat Classification 199910 A6.31 Oceanic ridge with hydrothermal effects same
EUNIS Habitat Classification 199811 A5.71 Oceanic ridge with hydrothermal effects same
EUNIS Habitat Classification 199712 A7.11 Oceanic ridge with hydrothermal effects same
Palaearctic Habitat Classification 199905 11.215 Hydrothermal benthic communities same
Palaearctic Habitat Classification 1997 11.215 Hydrothermal benthic communities same
Palaearctic Habitat Classification 1996 11.215   same
Palaearctic Habitat Classification 1993 11.215   same
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