Table 1. Enzyme activities, elemental sulfur ( S° ) content, 



stable carbon isotope ratio (d ^C) , presence of symbiotic 

 bacteria (S.B.), and methane consumption ( CH4 ) in organisms 

 from the Louisiana slope and the galapagos Rift hydrothermal 

 vents. Assays were conducted on symbiont containing tissues 

 (bivalve gills and vestimentif eran trophosome ) . One unit of 

 enzyme activity will convert 1 jimol of substrate to product. 

 RuBP, ribulose-bisphosphate carboxylase; ATP, ATP 

 sulfurylase; APS, adenosine-5 ' -phosphosulf ate reductase; 

 methanol, methanol dehydrogenase; sulfide, sulfide oxidase; 

 14 C, sulfide stimulated fixation of inorganic carbon, CH4, 

 methane consumption of gill or trophosome tissue, ND, not 

 detected; N, no; Y, yes; NT, not tested; WW, wet weight; and 

 EM, electron microscopy. 



Animal 



Enzyme activity (units/g WW/min) 



S° 14 C 3 13 C S.B. CH 4 



RuBP ATP APS CH3OH Sulfide (% WW) (E.M.) 



Louisiana slope animals 

 Mollusca 



Lucinidae 



Pseudomiltha s_p.. 



0.43 10.25 0.95 

 Mytilidae 



undescribed 



0.018 ND ND 

 Vesicomyidae 



Vesicomya cordata 



NT 29.58 ND 



ND 



2.03 0.15 



0.53 0.85 



ND NT 



ND 



ND 



Y -34.3 



N -52.1 



NT -39.8 



Y N 



Y Y 



Y NT 



Calvpt poena ponderosa 



NT NT NT 



NT 



NT 



4.4 



NT -37.4 



Y NT 



Vestimentif era 

 Lamellibrachiidae 



Lamellibrachia 2&. 



3.08 1.93 0.74 ND 3.46 4.4 Y -36.9 

 Undescribed family 

 undescribed sp. 



4.23 1.08 1.54 ND 3.56 0.8 Y -38.6 



Y N 



Y N 



Galapagos Rift hydrothermal vent animals 



Mollusca 



Mytilidae 



Bathymodiolus t hemophilus 



0.003 2.7 ND 



Vesicomyidae 



Calyptogena magnifica 



0.032 2.47 NT 



Riftiidae 



Piftia pachyptila 



ND 



0.92 ND 



ND 5.83 1.2 



Vestimentifera 



N -35.6 



Y -32.7 



Y N 



I N 



0.50 



57.74 23.3 



ND 



27.89 4.83 



Y -12.8 



Y N 



131 



