Аннотация:A small pogonophore from the Shagerrak, S~boglinum poseldonl lives in symbiosis with methane-oxidizing bacteria This was confirmed by the presence of 2 enzymes characteristic of bacterial Cl-metabol~sm methanol dehydrogenase and hexulosephosphate synthetase, in the bactena-contalning tissues Specific actlvlties were comparable to those found in free-living methane-ox~diz~ng bacteria and in bacter~a-contalnlng tiasups from other Invertebrates with symbiotic methanotrophs Stable carbon isotope ratios for tissues of pogonophores and other animals from the habitat were compared .iviththose for organlc matter in the sediment and for free and solbed hydrocarbon gases Free biogen~c methane (b"C = -80 3 "m PDB) was the carbon source for S poseldon~ ( b l ' C = -78 3 ".)in its bacteriacontaming posterior parts) Methane sorbed to the sedlment is probably not accessible to thc organism T ~s s u e of the bivalve mollusc T l ~y a s ~r a sarsi from the same habitat was less 13C-depleted (bl" = -37 4 to -39 5'',-) although more depleted than specimens found in sites with negligible methane The value for the b~valve can be explained by available bicarbonate deplet~on and selection for '*C by chemoautotrophic sulphur-ox~diz~ng symbiotic bacteria in the gllls No methylotrophlc enzymes were found in gill extracts A heterot~ophic polychaete appalently not influenced by symbiotic methanotrophs Leanlra sp has a b " ~-v a l u e (-20 0%") comparable to phytoplankton or organic matter from the sediment (-25 %o)
