Open AccessContrasting relationships between biogeochemistry and prokaryotic diversity depth profiles along an estuarine sediment gradient
Author(s) -
O'Sullivan Louise A.,
Sass Andrea M.,
Webster Gordon,
Fry John C.,
Parkes R. John,
Weightman Andrew J.
Publication year - 2013
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/1574-6941.12106
Subject(s) - methanogenesis , brackish water , archaea , estuary , methanomicrobiales , biology , sediment , euryarchaeota , biogeochemistry , environmental chemistry , sulfate reducing bacteria , seawater , anaerobic oxidation of methane , ecology , methanosarcina , methane , bacteria , salinity , chemistry , paleontology
Detailed depth profiles of sediment geochemistry, prokaryotic diversity and activity (sulphate reduction and methanogenesis) were obtained along an estuarine gradient from brackish to marine, at three sites on the C olne estuary ( UK ). Distinct changes in prokaryotic populations [ A rchaea , B acteria , sulphate‐reducing bacteria ( SRB ) and methanogenic archaea ( MA )] occurred with depth at the two marine sites, despite limited changes in sulphate and methane profiles. In contrast, the brackish site exhibited distinct geochemical zones (sulphidic and methanic) yet prokaryotic depth profiles were broadly homogenous. Sulphate reduction rates decreased with depth at the marine sites, despite nonlimiting sulphate concentrations, and hydrogenotrophic methanogenic rates peaked in the subsurface. Sulphate was depleted with depth at the brackish site, and acetotrophic methanogenesis was stimulated. Surprisingly, sulphate reduction was also stimulated in the brackish subsurface; potentially reflecting previous subsurface seawater incursions, anaerobic sulphide oxidation and/or anaerobic oxidation of methane coupled to sulphate reduction. D esulfobulbaceae , D esulfobacteraceae , M ethanococcoides and members of the M ethanomicrobiales were the dominant SRB and MA . Methylotrophic M ethanococcoides often co‐existed with SRB , likely utilising noncompetitive C 1‐substrates. Clear differences were found in SRB and MA phylotype distribution along the estuary, with only SRB 2‐a ( D esulfobulbus ) being ubiquitous. Results indicate a highly dynamic estuarine environment with a more complex relationship between prokaryotic diversity and sediment geochemistry, than previously suggested.