Bacterial scavenging of Mn and Fe in a mid- to far-field hydrothermal particle plume

Abstract

The horizontally advected plumes which originate from buoyant hydrothermal fluid discharges and subsequently mix with entrained ambient sea water have been detected hundreds of kilometres from their vent sources by distinctive chemical hydrothermal tracers such as 3He, Mn and Fe (refs 1–6). Non-conservative plume tracers, such as Mn and Fe, undergo dynamic oxidation–precipitation reactions as the plume is advected away from the vent sources1,4,7,8. Although some of these transformations may be mediated by microbial activity9,10, hydrothermal plumes have largely escaped microbiological examination beyond tens of metres from their vent origins11,12. Microbe–metal interactions in a hydrothermal plume were specifically addressed during our recent expedition (Vent–Plume '85) to the southern Juan de Fuca Ridge (SJFR). The early results, reported here, provide strong evidence of major microbiological influence over Mn scavenging and particulate-Mn distributions.