Biological communities at vent sites along the subduction zone off Oregon

An abundant deep-sea benthic community, dominated by the vestimentiferan tube worm, Lamellibrachia barhami , a giant white clam, Calyptogena sp., and a second clam, Solemya sp., was discovered along the northeast Pacific continental margin during dives of DSRV Alvin off Oregon. The localities are tectonically controlled and occur along submarine ridges that result from sediment deformation and accretion at the leading edge of plate subduction. Ancient sea-water buried with the sediment, dissolved methane and ammonia, and methane-derived carbonate are discharged to the ocean floor along this tectonically active margin. The authors hypothesize that the unusal benthic community is sustained by a chemosynthetic-energy metabolism based on the oxidation of methane by free living and symbiotic microbial populations.