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Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges.

The dispersal of hydrothermal fluids throughout the global ocean at active vent sites creates hydrothermal plumes. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents. Hydrothermal vents exist because the Earth is both geologically active and has large amounts of water on its surface and within its crust. Relative to the majority of the deep sea, the areas around hydrothermal vents are biologically more productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic bacteria and archaea found around hydrothermal vents form the base of the food chain, supporting diverse organisms including giant tube worms, clams, limpets, and shrimp. Active hydrothermal vents are thought to exist on Jupiter's moon Europa and Saturn's moon Enceladus, and it is speculated that ancient hydrothermal vents once existed on Mars. The conditions of these vents have been shown to support the synthesis of molecules important to life. Some evidence suggests that certain vents such as alkaline hydrothermal vents or those containing supercritical CO2 are more conducive to the formation of these organic molecules.

Hydrothermal vents in the deep ocean typically form along the mid-ocean ridges, such as the East Pacific Rise and the Mid-Atlantic Ridge.

Hydrothermal plumes are fluid entities that manifest where hydrothermal fluids are expelled into the overlying water column at active hydrothermal vent sites. Hydrothermal vent fluids harbor temperatures (~40 to >400 °C) well above that of ocean floor seawater (~4 °C), meaning that hydrothermal fluid is less dense than the surrounding seawater and will rise through the water column due to buoyancy, forming a hydrothermal plume; therefore, the phase during which hydrothermal plumes rise through the water column is known as the "buoyant plume" phase.

Dissolved gases, such as H2, H2S, and CH4, and metals, such as Fe and Mn, present at high concentrations in hydrothermal vent fluids relative to seawater may also be diagnostic of hydrothermal plumes and thus active venting; however, these components are reactive and are thus less suitable as tracers of hydrothermal activity.

Life has traditionally been seen as driven by energy from the sun, but deep-sea organisms have no access to sunlight, so biological communities around hydrothermal vents must depend on nutrients found in the dusty chemical deposits and hydrothermal fluids in which they live. Hydrothermal vent communities are able to sustain such vast amounts of life because vent organisms depend on chemosynthetic bacteria for food. The water from the hydrothermal vent is rich in dissolved minerals and supports a large population of chemoautotrophic bacteria.

Organisms living at the edge of hydrothermal vent fields, such as pectinid scallops, also carry endosymbionts in their gills, and as a result their bacterial density is low relative to organisms living nearer to the vent.

The discovery of a vent in the Pacific Ocean offshore of Costa Rica, named the Medusa hydrothermal vent field (after the serpent-haired Medusa of Greek mythology), was announced in April 2007. The Ashadze hydrothermal field (13°N on the Mid-Atlantic Ridge, elevation -4200 m) was the deepest known high-temperature hydrothermal field until 2010, when a hydrothermal plume emanating from the Beebe site (18°33′N 81°43′W, elevation -5000 m) was detected by a group of scientists from NASA Jet Propulsion Laboratory and Woods Hole Oceanographic Institution.

Mining of an active deep sea hydrothermal vent ecosystem would depend on the recolonization of chemosynthetic bacteria, and therefore the continuation of the hydrothermal vent fluid as it is the main hydrothermal energy source.

Although some biogeochemists such as Rogers et al. (2012) have identified sites of hydrothermal vents, the locations of known hydrothermal vent formations in deep sea systems is not well understood. Endeavour Hydrothermal Vents – Group of Pacific Ocean hydrothermal vents

Quick Facts

• Mining of an active deep sea hydrothermal vent ecosystem would depend on the recolonization of chemosynthetic bacteria, and therefore the continuation of the hydrothermal vent fluid as it is the main hydrothermal energy source.
• The dispersal of hydrothermal fluids throughout the global ocean at active vent sites creates hydrothermal plumes.
• Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents.
• Hydrothermal plumes are fluid entities that manifest where hydrothermal fluids are expelled into the overlying water column at active hydrothermal vent sites.
• Endeavour Hydrothermal Vents – Group of Pacific Ocean hydrothermal vents

Source material: Wikipedia - "Hydrothermal vent". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.