Biological communities at vent sites along the subduction zone off Oregon

Abstract

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
\naccretion at the leading edge of plate subduction. Ancient sea-water buried with the sediment, dissolved methane and ammonia, and methane-derived carbonate are discharged
\nto the ocean floor along this tectonically active margin. We hypothesize that the unusual benthic community is sustained by a chemosynthetic-energy metabolism based on the oxidation of methane by free living and symbiotic microbial populations.
\nThese organisms represent another significant adaptation of deep-sea biota to a site where the abundanc of food (in this case not directly related to particulate input from the sea surface but to tectonically generated methane), allows higher than normal levels of productivity and metabolism, despite the high pressures and low temperature of the deep-sea habitat. It is tempting to relate the global distribution of such faunas to chemosynthetic food sources generated by tectonic forces.