Editing Cold seep (section)

=== Chemosynthetic communities ===

[[File:bacterial mat.jpg|thumb|[[Bacterial mat]] consisting of sulfide-oxidizing bacteria ''[[Beggiatoa]]'' spp. at a seep on [[Blake Ridge]], off South Carolina. The red dots are range-finding laser beams.]]

Biological research in cold seeps and hydrothermal vents has been mostly focused on the [[microbiology]] and the prominent  macro-invertebrates thriving on [[Chemosynthesis|chemosynthetic]] microorganisms.<ref name="Vanreusel 2010" /> Much less research has been done on the smaller [[benthic]] fraction at the size of the [[meiofauna]] (<1&nbsp;mm).<ref name="Vanreusel 2010" />

A community composition's orderly shift from one set of species to another is called [[ecological succession]].<ref name="Hsing 2010" />

The first type of organism to take advantage of this deep-sea energy source is [[bacteria]].<ref name="Hsing 2010" /> Aggregating into [[bacterial mat]]s at cold seeps, these bacteria metabolize methane and [[hydrogen sulfide]] (another gas that emerges from seeps) for energy.<ref name="Hsing 2010" /> This process of obtaining energy from chemicals is known as [[chemosynthesis]].<ref name="Hsing 2010" />

[[File:Noaamussels 600A musselNearBrinePoolExpLophelia II 2010.jpg|left|thumb|A mussel bed at the edge of the brine pool]]

During this initial stage, when methane is relatively abundant, dense [[mussel]] beds also form near the cold seep.<ref name="Hsing 2010" /> Mostly composed of species in the genus ''[[Bathymodiolus]]'', these mussels do not directly consume food;<ref name="Hsing 2010" /> Instead, they are nourished by [[symbiotic]] bacteria that also produce energy from methane, similar to their relatives that form mats.<ref name="Hsing 2010" /> Chemosynthetic bivalves are prominent constituents of the fauna of cold seeps and are represented in that setting by five families: [[Solemyidae]], [[Lucinidae]], [[Vesicomyidae]], [[Thyasiridae]], and [[Mytilidae]].<ref name="Oliver 2011" />

This microbial activity produces [[calcium carbonate]], which is deposited on the [[seafloor]] and forms a layer of rock.<ref name="Hsing 2010" /> During a period lasting up to several decades, these rock formations attract [[siboglinidae|siboglinid]] [[Lamellibrachia|tubeworms]], which settle and grow along with the mussels.<ref name="Hsing 2010" /> Like the mussels, tubeworms rely on chemosynthetic bacteria (in this case, a type that needs [[hydrogen sulfide]] instead of methane) for survival.<ref name="Hsing 2010" /> True to any symbiotic relationship, a tubeworm also provides for its bacteria by appropriating hydrogen sulfide from the environment.<ref name="Hsing 2010" /> The sulfide not only comes from the water, but is also mined from the sediment through an extensive "root" system that a tubeworm "bush" establishes in the hard, carbonate substrate.<ref name="Hsing 2010" /> A tubeworm bush can contain hundreds of individual worms, which can grow a meter or more above the sediment.<ref name="Hsing 2010" />

Cold seeps do not last indefinitely. As the rate of gas seepage slowly decreases, the shorter-lived, methane-hungry mussels (or more precisely, their methane-hungry bacterial symbionts) start to die off.<ref name="Hsing 2010" /> At this stage, tubeworms become the dominant organism in a seep community.<ref name="Hsing 2010" /> As long as there is some sulfide in the sediment, the sulfide-mining tubeworms can persist.<ref name="Hsing 2010" /> Individuals of one tubeworm species ''[[Lamellibrachia luymesi]]'' have been estimated to live for over 250 years in such conditions.<ref name="Hsing 2010" />

{|
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||[[File:Siboglinidae.jpg|thumb|"Roots" of tubeworms also provide a supply of hydrogen sulfide from the sediment to the bacteria inside these tubeworms.]]
||[[File:Lamellibrachia luymesi.png|left|thumb|Symbiotic vestimentiferan tubeworm ''[[Lamellibrachia luymesi]]'' from a cold seep at 550&nbsp;m depth in the Gulf of Mexico. In the sediments around the base are orange bacterial mats of the sulfide-oxidizing bacteria ''[[Beggiatoa]]'' spp. and empty shells of various clams and snails, which are also common inhabitants of the seeps.<ref name="Boetius 2005" />]]
||[[File:cold seep community.jpg|left|thumb|[[Lamellibrachia|Tubeworms]], soft [[coral]]s, and chemosynthetic mussels at a seep located {{convert|3000|m|ft|abbr=on}} down on the Florida Escarpment. [[Eelpout]]s,  a [[Galatheidae|Galatheid]] crab, and an [[Alvinocarididae|alvinocarid]] shrimp feed on mussels damaged during a sampling exercise.]]
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