The importance of burrows in cold-seeps

Infaunal activities and burrows at seafloor play an important role in respect of biogeochemical reactions (e.g. Glud, 2008; Marine Biology Research). Cold-seep fluids, which are rich in reduced compounds such as methane and hydrogen sulfides, lead to extensive biogeochemical reactions when the pore fluid encounters oxic sea water.
Recently, we carried out some in situ burrow castings in cold-seeps in Sagami Bay, central Japan, and revealed the existence of large and complex burrows even in cold-seeps at the deep-sea environments (Seike et al., 2012; Biology Letters). Although we have not obtained any environmental aspect of these burrows in modern cold-seeps, we found some insights about their geochemical importance from fossilized burrows in ancient chemosynthetic communities.
We analyzed some trace fossils, which were originally hollow tube in the sediment but were filled with carbonate cements, drawing on the results of optical and SEM observations and carbon isotope analyses. The optical and SEM observations revealed that the carbonate cements were repeatedly precipitated. The carbonates are characterized by depleted carbon isotopic compositions which indicate the presence of anaerobic oxidation of methane within the burrows. These lines of evidence strongly suggest that the cold-seep fluids repeatedly passed through the burrows. In addition, in the case of infaunal chemosymbiotic bivalves, which make burrows, can be characterized in terms of the continuity of the fossil record extending at least from late Jurassic to the Recent (Jenkins et al., in press; Acta Palaeontologica Polonica). These results suggest that burrows have acted as places for the oxidation of methane in cold-seeps through geologic time.

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First Name: 
Robert G.
Last Name: 
Jenkins
Telephone: 
+81-76-264-6512
Affiliation: 
Kanazawa University
First Name: 
Koji
Last Name: 
Seike
Affiliation: 
University of Tokyo
First Name: 
Hiromi
Last Name: 
Watanabe
Affiliation: 
JAMSTEC
First Name: 
Hidetaka
Last Name: 
Nomaki
Affiliation: 
JAMSTEC
First Name: 
Kei
Last Name: 
Sato
Affiliation: 
University of Tokyo
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Ecological Interactions
Abstract ID: 
CBE5-153