Detoxification of sulphidic African shelf waters by blooming chemolithotrophs

摘要: Coastal waters support approximately 90 per cent of global fisheries and are therefore an important food reserve for our planet. Eutrophication these waters, due to human activity, leads severe oxygen depletion the episodic occurrence hydrogen sulphide-toxic multi-cellular life-with disastrous consequences coastal ecosytems. Here we show that area 7,000 km(2) African shelf, covered by sulphidic water, was detoxified blooming bacteria oxidized biologically harmful sulphide environmentally harmless colloidal sulphur sulphate. Combined chemical analyses, stoichiometric modelling, isotopic incubations, comparative 16S ribosomal RNA, functional gene sequence analyses fluorescence in situ hybridization indicate detoxification proceeded chemolithotrophic oxidation with nitrate mainly catalysed two discrete populations gamma- epsilon-proteobacteria. Chemolithotrophic bacteria, accounting 20 bacterioplankton created a buffer zone between toxic subsurface oxic surface where fish other nekton live. This is first time large-scale chemolithotrophs has been observed open-ocean system. The data suggest can be completely consumed and, thus, overlooked remote sensing or monitoring shallow waters. Consequently, bottom on continental shelves may more common than previously believed, could have but as yet neglected effect benthic communities.