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Water-sediment exchanges control microbial processes associated with leaf litter degradation in the hyporheic zone: a microcosm study

Navel, Simon and Mermillod-Blondin, Florian and Montuelle, Bernard and Chauvet, Eric and Simon, Laurent and Marmonier, Pierre Water-sediment exchanges control microbial processes associated with leaf litter degradation in the hyporheic zone: a microcosm study. (2011) Microbial Ecology, vol. 61 (n° 4). pp. 968-79. ISSN 0095-3628

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Official URL: http://dx.doi.org/10.1007/s00248-010-9774-7

Abstract

The present study aimed to experimentally quantify the influence of a reduction of surface sediment permeability on microbial characteristics and ecological processes (respiration and leaf litter decomposition) occurring in the hyporheic zone (i.e. the sedimentary interface between surface water and groundwater). The physical structure of the water-sediment interface was manipulated by adding a 2-cm layer of coarse sand (unclogged systems) or fine sand (clogged systems) at the sediment surface of slow filtration columns filled with a heterogeneous gravel/sand sedimentary matrix. The influence of clogging was quantified through measurements of hydraulic conductivity, water chemistry, microbial abundances and activities and associated processes (decomposition of alder leaf litter inserted at a depth of 9 cm in sediments, oxygen and nitrate consumption by microorganisms). Fine sand deposits drastically reduced hydraulic conductivity (by around 8-fold in comparison with unclogged systems topped by coarse sand) and associated water flow, leading to a sharp decrease in oxygen (reaching less than 1 mg L(-1) at 3 cm depth) and nitrate concentrations with depth in sediments. The shift from aerobic to anaerobic conditions in clogged systems favoured the establishment of denitrifying bacteria living on sediments. Analyses performed on buried leaf litter showed a reduction by 30% of organic matter decomposition in clogged systems in comparison with unclogged systems. This reduction was linked to a negative influence of clogging on the activities and abundances of leaf-associated microorganisms. Finally, our study clearly demonstrated that microbial processes involved in organic matter decomposition were dependent on hydraulic conductivity and oxygen availability in the hyporheic zone.

Item Type:Article
Additional Information:Thanks to Springer Verlag editor. The definitive version is available at http://link.springer.com/article/10.1007%2Fs00248-010-9774-7
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université Claude Bernard-Lyon I - UCBL (FRANCE)
French research institutions > Institut national de recherche en sciences et technologies pour l’environnement et l’agriculture - CEMAGREF (FRANCE)
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Deposited By: Eric Chauvet
Deposited On:21 Mar 2014 13:06

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