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Cold seep: Wikis

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Ocean habitats
Littoral zone
Intertidal zone
Neritic zone
Continental shelf
Kelp forests
Coral reefs
Ocean banks
Continental margin
Straits
Pelagic zone
Oceanic zone
Seamounts
Hydrothermal vents
Cold seeps
Demersal zone
Benthic zone
Aquatic ecosystems
Aquatic layers
Wild fisheries
Land habitats
Tubeworms, soft corals and chemosynthetic mussels at a seep located 3,000 m (9,843 ft) down on the Florida Escarpment. Eelpouts, a Galatheid crab and an alvinocarid shrimp feed on mussels damaged during a sampling exercise.
Beggiatoal bacterial mat at a seep on Blake Ridge, off South Carolina. The red dots are range-finding laser beams.
Late Cretaceous cold seep deposit in the Pierre Shale, southwest South Dakota.

A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. Cold seeps constitute a biome supporting several endemic species.

Entire communities of light-independent organisms - known as extremophiles - develop in and around cold seeps, most relying on a symbiotic relationship with chemoautotrophic bacteria. These prokaryotes, both Archaea and Bacteria, process sulfides and methane through chemosynthesis into chemical energy. More complex organisms, such as vesicomyid clams and siboglinid tube worms use this energy to power their own life processes. In exchange, the microbes are provided with both safety and a reliable source of food. Other microbes form mats that blanket sizable areas.

Aside from whale fall communities, cold seeps and hydrothermal vents are similar in that they are the only known communities that do not rely on photosynthesis for food and energy production. Unlike hydrothermal vents which are volatile and ephemeral environments, cold seeps emit at a slow and dependable rate. Likely owing to the cooler temperatures and stability, many cold seep organisms are much longer-lived than those inhabiting hydrothermal vents. Recent research has revealed that the seep tubeworm Lamellibrachia luymesi may be the longest living noncolonial invertebrate known, with a lifespan between 170 and 250 years.

Cold seeps were discovered in 1984 by Dr. Charles Paull in the Gulf of Mexico at a depth of 3,200 meters (10,499 ft). Since then, seeps have been discovered in other parts of the world's oceans, including the Monterey Canyon just off Monterey Bay, California, the Sea of Japan, off the Pacific coast of Costa Rica, in the Atlantic off of Africa, in waters off the coast of Alaska, and under an ice shelf in Antarctica.[1] The deepest seep community known is found in the Japan trench at a depth of 7,326 m (24,035 ft).

Cold seeps develop unique topography over time, where reactions between methane and seawater create carbonate rock formations and reefs. These reactions may also be dependent on bacterial activity. Ikaite, a hydrous calcium carbonate, can be associated with oxidizing methane at cold seeps.

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Fossilized records

Cold seep deposits are found throughout the Phanerozoic rock record, especially in the Late Mesozoic and Cenozoic (see for an example, Kaim et al., 2008). These fossil cold seeps are characterized by mound-like topography (where preserved), coarsely-crystalline carbonates, and abundant mollusks and brachiopods.

References

Kaim, A., Jenkins, R., and Warén, A. 2008. Provannid and provannid-like gastropods from the Late Cretaceous cold seeps of Hokkaido (Japan) and the fossil record of the Provannidae (Gastropoda: Abyssochrysoidea). Zoological Journal of the Linnean Society, Volume 154, Number 3, p. 421-436.

External links


Simple English

A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich liquids leak out of the earth's crust, often in the form of a brine pool. Cold seeps form a biome supporting several native species.

Cold seeps change the shape of the ocean floor over time, where reactions between methane and seawater create carbonate rock formations and reefs. These reactions may change when bacteria are present.

Contents

Types

File:NOAAseep
These craters mean a brine pool has formed here. Salt from brine pools seeps through the seafloor and covers the nearby rock.

Cold seeps at different depths have different names. Other kinds of cold seeps are:

  • oil/gas seeps
  • gas seeps: methane seeps
  • gas hydrate seeps
  • brine seeps are forming brine pools
  • pockmarks
  • mud volcanos

Formation and ecological succession

Cold seeps occur over cracks in the seafloor caused by the movement of the earth's crust. Oil and methane "seep" out of those cracks, get dissolved by tiny bits of rock, and emerge over an area several hundred meters wide.

Methane (CH4) is the main part of what we commonly refer to as natural gas. But in addition to being an important energy source for humans, methane also forms the basis of a cold seep ecosystem.


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