Contrasting relationships between biogeochemistry and prokaryotic diversity depth profiles along an estuarine sediment gradient

O'Sullivan, Louise Anne, Sass, Andrea, Webster, Gordon ORCID: https://orcid.org/0000-0002-9530-7835, Fry, John C., Parkes, Ronald John and Weightman, Andrew John ORCID: https://orcid.org/0000-0002-6671-2209 2013. Contrasting relationships between biogeochemistry and prokaryotic diversity depth profiles along an estuarine sediment gradient. FEMS Microbiology Ecology 85 (1) , pp. 143-157. 10.1111/1574-6941.12106

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Abstract

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 Colne estuary (UK). Distinct changes in prokaryotic populations (Archaea, Bacteria, 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 non-limiting 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. Desulfobulbaceae, Desulfobacteraceae, Methanococcoides and members of the Methanomicrobiales were the dominant SRB and MA. Methylotrophic Methanococcoides often co-existed with SRB, likely utilising non-competitive C1-substrates. Clear differences were found in SRB and MA phylotype distribution along the estuary, with only SRB2-a (Desulfobulbus) being ubiquitous. Results indicate a highly dynamic estuarine environment with a more complex relationship between prokaryotic diversity and sediment geochemistry, than previously suggested.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Publisher:	Wiley-Blackwell
ISSN:	0168-6496
Funders:	NERC
Last Modified:	15 Nov 2024 22:28
URI:	https://orca.cardiff.ac.uk/id/eprint/44941

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