Controls on Carbonate Communities at Methane Seeps

Controls on Carbonate Communities at Methane Seeps.

Authigenic carbonates precipitate in sediments where anaerobic methane oxidizing consortia mediate high DIC and alkalinity conditions. Carbonates are a widespread feature at methane seeps as well as at serpentenite vent sites. They support a distinctive invertebrate community of microbial grazers, suspension feeders, carnivores and even lithovores (rock eaters). Through a series of mensurative and manipulative transplant experiments we have examined the roles of methane seepage, hydrography (O2, T, depth), and biotic habitat in structuring macrofaunal assemblages on carbonates. Off Costa Rica, rocks at active seep sites support a gastropod-dominated assemblage distinct from the polychaete-dominated rocks at inactive sites. Carbonates at active sites associated with biogenic habitats (mussels/tubeworms) support faunas different from carbonates in a sediment matrix (clam bed or microbial mat habitats), and all differ from the sediment infauna. Fauna on inactive carbonates are more sensitive to changes in hydrography of overlying waters than those at active sites. Similar responses to seepage are exhibited by carbonate faunas at Hydrate Ridge. Rocks transplanted from inactive to active sites and vice versa exhibit shifts in archaeal and macrofaunal composition and isotope signatures after one year, illustrating dynamic responses to changing methane seepage.

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First Name: 
Lisa
Last Name: 
Levin
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858-534-3579
Affiliation: 
Scripps Institution of Oceanography
First Name: 
Guillermo
Last Name: 
Mendoza
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Scripps Institution of Oceanography
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Benjamin
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Grupe
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Scripps Institution of Oceanography
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David
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Case
Affiliation: 
California Institute of Technology
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Greg
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Rouse
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Scripps Institution of Oceanography
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Victoria
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Orphan
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California Institute of Technology
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Distribution and abundance
Trophic relations (including symbiosis)
Ecological Interactions
Abstract ID: 
CBE5-112