title: Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.
abstract: Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species,Rimicaris exoculata, the vent chimney-dwelling mussel,Bathymodiolus azoricus,Branchipolynoe seepensis, a commensal worm ofB. azoricus, and the gastropodPeltospira smaragdinashowed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species inR. exoculata, whereas inB. azoricus and B. seepensisarsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life.
authors.affiliation: Trace Element Analysis Core, HB 6105 Fairchild Hall Dartmouth College, Hanover NH 03755.
authors.forename: Vivien F
authors.initials: VF
authors.lastname: Taylor
authors.forename: Brian P
authors.initials: BP
authors.lastname: Jackson
authors.forename: Matthew
authors.initials: M
authors.lastname: Siegfried
authors.forename: Jana
authors.initials: J
authors.lastname: Navratilova
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Francesconi
authors.forename: Julie
authors.initials: J
authors.lastname: Kirshtein
authors.forename: Mary
authors.initials: M
authors.lastname: Voytek