Time-scales of hydrological forcing on the geochemistry and bacterial community structure of temperate peat soils

Nunes, Flávia L. D.; Aquilina, Luc; Ridder, Jo De; Francez, André-Jean; Quaiser, Achim; Caudal, Jean-Pierre; Vandenkoornhuyse, Philippe; Dufresne, Alexis

doi:10.1038/srep14612

Cited by 12 publications

(8 citation statements)

References 38 publications

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“…Bogs, wherein water table position and peat accumulation capacity are governed strongly by the balance between precipitation and evapotranspiration, are particularly vulnerable to climate change [ Winter , ]. Climate‐induced changes in the hydrological regimes of peatlands significantly influence microbial community structure, which may have profound effects on peat decomposition and carbon sequestration [ Nunes et al ., ; Peltoniemi et al ., ]. Changes in bacterial community structure also have important links to methylmercury production in peatlands [ Strickman et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

Haynes

Kane

Potvin

et al. 2017

Global Biogeochemical Cycles

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Climate change is likely to significantly affect the hydrology, ecology, and ecosystem function of peatlands, with potentially important but unclear impacts on mercury mobility within and transport from peatlands. Using a full‐factorial mesocosm approach, we investigated the potential impacts on mercury mobility of water table regime changes (high and low) and vegetation community shifts (sedge‐dominated, Ericaceae‐dominated, or unmanipulated control) in peat monoliths at the PEATcosm mesocosm facility in Houghton, Michigan. Lower and more variable water table regimes and the loss of Ericaceae shrubs act significantly and independently to increase both total Hg and methylmercury concentrations in peat pore water and in spring snowmelt runoff. These differences are related to enhanced peat decomposition and internal regeneration of electron acceptors which are more strongly related to water table regime than to plant community changes. Loss of Ericaceae shrubs and an increase in sedge cover may also affect Hg concentrations and mobility via oxygen shuttling and/or the provision of labile root exudates. Altered hydrological regimes and shifting vegetation communities, as a result of global climate change, are likely to enhance Hg transport from peatlands to downstream aquatic ecosystems.

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Section: Introductionmentioning

confidence: 99%

Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

Haynes

Kane

Potvin

et al. 2017

Global Biogeochemical Cycles

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“…Understanding the response of peatland soil microbial communities to drought is of major importance because of their key role as decomposers. Drought often enhances the activity of peatland microorganisms (Fenner & Freeman, ), concomitantly with shifts in communities’ composition (Nunes et al., ). However, in some peatlands, drought had only little impact on bacterial and fungal communities (Peltoniemi et al., ).…”

Section: Introductionmentioning

confidence: 99%

“…The consequences of drought on peatland microbial consumers and their body mass structure remain largely unknown. Most studies focused on low trophic levels (bacteria and fungi) (Jaatinen, Fritze, Laine, & Laiho, ; Nunes et al., ) and little empirical evidence exist for predicting future changes within multiple trophic levels (Lindo, ). Yet, some studies showed the importance of trophic interactions among multiple trophic levels in driving soil decomposition processes (Sauvadet et al., ).…”

Section: Introductionmentioning

confidence: 99%

Predator–prey mass ratio drives microbial activity under dry conditions in Sphagnum peatlands

Reczuga

Lamentowicz

Mulot

et al. 2018

Ecology and Evolution

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Mid‐ to high‐latitude peatlands are a major terrestrial carbon stock but become carbon sources during droughts, which are increasingly frequent as a result of climate warming. A critical question within this context is the sensitivity to drought of peatland microbial food webs. Microbiota drive key ecological and biogeochemical processes, but their response to drought is likely to impact these processes. Peatland food webs have, however, been little studied, especially the response of microbial predators. We studied the response of microbial predators (testate amoebae, ciliates, rotifers, and nematodes) living in Sphagnum moss carpet to droughts, and their influence on lower trophic levels and on related microbial enzyme activity. We assessed the impact of reduced water availability on microbial predators in two peatlands using experimental (Linje mire, Poland) and natural (Forbonnet mire, France) water level gradients, reflecting a sudden change in moisture regime (Linje), and a typically drier environment (Forbonnet). The sensitivity of different microbial groups to drought was size dependent; large sized microbiota such as testate amoebae declined most under dry conditions (−41% in Forbonnet and −80% in Linje). These shifts caused a decrease in the predator–prey mass ratio (PPMR). We related microbial enzymatic activity to PPMR; we found that a decrease in PPMR can have divergent effects on microbial enzymatic activity. In a community adapted to drier conditions, decreasing PPMR stimulated microbial enzyme activity, while in extreme drought experiment, it reduced microbial activity. These results suggest that microbial enzymatic activity resulting from food web structure is optimal only within a certain range of PPMR, and that different trophic mechanisms are involved in the response of peatlands to droughts. Our findings confirm the importance of large microbial consumers living at the surface of peatlands on the functioning of peatlands, and illustrate their value as early warning indicators of change.

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“…The observed differences between the SD-, MD-, and HDpeat in solute release could also be related to their pore-related parameters, such as porosity and proportion of the immobile pore regions detected via BTC analysis. Immobile zones provide an opposing effect on DOC concentrations where stagnant pore water zones may serve as hot spots for DOM production, as they represent the preferred habitat for microorganisms (Nunes et al, 2015;Rezanezhad et al, 2016). Immobile pore regions also increase the average pore water velocity and preferential flow thereby reducing the residence time of the water in the mobile pore regions and the potential for solute exchange between liquid and solid phase (Tiemeyer et al, 2017).…”

Section: Effect Of Peat Decomposition Degreementioning

confidence: 99%

Sulfate Mobility in Fen Peat and Its Impact on the Release of Solutes

Gosch

Townsend

Kreuzburg

et al. 2019

Front. Environ. Sci.

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Sea-level rise coupled with land subsidence from wetland drainage exposes increasingly large areas of coastal peatlands to seawater intrusion. Seawater contains high concentrations of sulfate (SO 4 2−), which can alter the decomposition of organic matter thereby releasing organic and inorganic solutes from peat. In this study, a flow-through reactor system was used in order to examine the transport of SO 4 2− through peat as well as its effect on solute release. Moderately-decomposed fen peat samples received input solutions with SO 4 2− concentrations of 0, 100, 700, and 2,700 mg L −1 ; sample effluent was analyzed for a variety of geochemical parameters including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and total dissolved nitrogen (TDN) as well as the concentrations of major cations and anions. The input solution remained anoxic throughout the experiment; however, no signs of a pronounced SO 4 2− reduction were detected in the effluent. SO 4 2− transport in the fen peat resembled non-reactive bromide (Br −) transport, indicating that in the absence of SO 4 2− reduction the anion may be considered a conservative tracer. However, slightly elevated concentrations of DOC and TDN, associated with raised SO 4 2− levels, suggest the minor desorption of organic acids through anion exchange. An increased solute release due to stimulated decomposition processes, including SO 4 2− reduction, was observed for samples with acetate as an additional marine carbon source included in their input solution. The solute release of peats with different degrees of decomposition differed greatly under SO 4 2−-enriched conditions where strongly-decomposed fen peat samples released the highest concentrations of DOC, DIC and TDN.

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Time-scales of hydrological forcing on the geochemistry and bacterial community structure of temperate peat soils

Cited by 12 publications

References 38 publications

Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

Predator–prey mass ratio drives microbial activity under dry conditions in Sphagnum peatlands

Sulfate Mobility in Fen Peat and Its Impact on the Release of Solutes

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