Effect of redox conditions on bacterial community structure in Baltic Sea sediments with contrasting phosphorus fluxes.

Anne K Steenbergh,Caroline P Slomp,Hendrikus J Laanbroek,Paul L E Bodelier

doi:10.1371/journal.pone.0092401

Anne K Steenbergh, Caroline P Slomp + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0092401

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Journal: PloS one	Publication Date: Mar 25, 2014
Citations: 44	License type: CC BY 4.0

Affiliation: Utrecht University, Netherlands Institute of Ecology

Abstract

Phosphorus release from sediments can exacerbate the effect of eutrophication in coastal marine ecosystems. The flux of phosphorus from marine sediments to the overlying water is highly dependent on the redox conditions at the sediment-water interface. Bacteria are key players in the biological processes that release or retain phosphorus in marine sediments. To gain more insight in the role of bacteria in phosphorus release from sediments, we assessed the effect of redox conditions on the structure of bacterial communities. To do so, we incubated surface sediments from four sampling sites in the Baltic Sea under oxic and anoxic conditions and analyzed the fingerprints of the bacterial community structures in these incubations and the original sediments. This paper describes the effects of redox conditions, sampling station, and sample type (DNA, RNA, or whole-cell sample) on bacterial community structure in sediments. Redox conditions explained only 5% of the variance in community structure, and bacterial communities from contrasting redox conditions showed considerable overlap. We conclude that benthic bacterial communities cannot be classified as being typical for oxic or anoxic conditions based on community structure fingerprints. Our results suggest that the overall structure of the benthic bacterial community has only a limited impact on benthic phosphate fluxes in the Baltic Sea.

Highlights

Due to eutrophication coastal ecosystems are increasingly under threat by the spreading of so-called dead zones, in which oxygen concentrations fall below a level necessary for higher life [1]
The influence of microbes on P release is potentially sensitive to the absence or presence of oxygen, as this determines which metabolic pathways can be used by bacterial communities
The digitized Denaturing Gradient Gel Electrophoresis (DGGE) lane profiles of this dataset were analyzed by Functional PCA (FPCA)

Summary

Introduction

Due to eutrophication coastal ecosystems are increasingly under threat by the spreading of so-called dead zones, in which oxygen concentrations fall below a level necessary for higher life [1]. Because phosphorus (P) release from sediments is enhanced under low oxygen conditions, a positive feedback loop between eutrophication, low oxygen concentrations and P release from sediments can occur [2,3,4]. Various studies have shown that there is an intricate relation between microbial processes and benthic P release, with microbes contributing both to enhanced release and retention of P in sediments [5,6,7]. Previous studies have shown correlations between redox conditions and prokaryote community structure in coastal Baltic Sea sediments [8,9]. In observational studies it is often difficult to isolate the effect of redox condition on community structure form other, often co-varying, environmental variables

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