ARSENIC SPECIATION IN SHRIMP AND MUSSEL FROM THE MID-ATLANTIC HYDROTHERMAL VENTS

Specimens of shrimp (Rimicaris exoculata) and mussel (Bathymodiolus pu teoserpentis) were collected 3500 m below the ocean surface at the hyd rothermal vents of the mid-Atlantic Ridge (TAG and Snake Pit sites, re spectively). Arsenic, a potentially toxic element, is among the substa nces emitted by the hydrothermal vents. The hydrothermal vent shrimp, which are known to be a primary consumer of the primary producing chem olithoautotrophic bacteria, contained arsenic at 13 mu g g(-1) almost exclusively as arsenobetaine (AsB). Arsenic was present in the soft:is sues of the mussel at 40 mu g g(-1) and the major part of the extracta ble arsenic species in the adductor muscle/mantle tissues and in the g ill were present as dimethylarsinylriboside-derivatives (arsenosugrars ), while AsB was present at 16 and 3.6%, respectively, in these tissue s. In spite of the absence of biosynthetically active algae, the patte rn of arsenic species found in the shrimp and mussel species in the de ep-sea is similar to that found in their counterparts from the ocean s urface. It is concluded that the autotrophic bacteria of the hydrother mal vent ecosystem and the symbiotic bacteria harboured in the mussel species are responsible for the biosynthesis of the organoarsenicals d etected in the two hydrothermal vent animal species. It is not known i f the formation of the same organoarsenicals in the surface and deep s ea ecosystems is primarily a detoxification process of inorganic arsen ic, or whether these compounds play a physiological role. (C) 1997 Els evier Science B.V.