PHYSIOLOGICAL ECOLOGY OF SULFIDE METABOLISM IN HYDROTHERMAL VENT AND COLD SEEP VESICOMYID CLAMS AND VESTIMENTIFERAN TUBE WORMS

The primary ecosystem-structuring organisms at many hydrothermal vents and cold seeps are phylogenetically related and quite similar physiol ogically and anatomically. Vestimentiferan tube worms and Vesicomyid c lams in particular all rely on chemoautotrophic sulfur-oxidizing symbi onts and have blood which binds sulfide with high affinity and capacit y. However, there are significant differences between cold seep and hy drothermal vent environments, including large differences in flow rate of the emitted fluid and the chemistry of that fluid. Here we review extant data on the hydrothermal vent species, present new data on the physiologically relevant chemical microhabitat of cold seep vestimenti ferans and vesicomyids, and compare the physiological ecology of the s eep species to their hydrothermal vent relatives.