Benthic nitrogen metabolism in a macrophyte meadow (Vallisneria spiralis L.) under increasing sedimentary organic matter loads

Soana, Elisa; Naldi, Mariachiara; Bonaglia, Stefano; Racchetti, Erica; Castaldelli, Giuseppe; Brüchert, Volker; Viaroli, Pierluigi; Bartoli, Marco

doi:10.1007/s10533-015-0104-5

Cited by 35 publications

(73 citation statements)

References 71 publications

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“…Benthic vegetation can inhibit or stimulate N loss via denitrification coupled to nitrification in the rhizosphere. Inhibition generally occurs in net autotrophic aquatic environments where inorganic N is limiting (Risgaard-Petersen and Jensen, 1997;Ottosen et al, 1999;Risgaard-Petersen, 2004), while stimulation can occur where N is abundant and the plant-microbe community competition is attenuated (Nizzoli et al, 2014;Soana et al, 2015). A side effect of in-stream N removal is the production of the greenhouse gas nitrous oxide (N 2 O) as an intermediate of several N cycle processes (Reay et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Vegetated canals mitigate nitrogen surplus in agricultural watersheds

Castaldelli

Soana

Racchetti

et al. 2015

Agriculture, Ecosystems & Environment

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Section: Introductionmentioning

confidence: 99%

Vegetated canals mitigate nitrogen surplus in agricultural watersheds

Castaldelli

Soana

Racchetti

et al. 2015

Agriculture, Ecosystems & Environment

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“…Our experimental approach involves the incubation of microcosms under controlled conditions after an acclimatization period (Dalsgaard ; Ribaudo et al ; Soana et al ; Racchetti et al ). Water, sediments, plants, and macrofauna were collected from a perifluvial area of the Mincio River (Northern Italy) in November 2013.…”

Section: Methodsmentioning

confidence: 99%

“…Total dissolved inorganic carbon (TCO 2 ), ammonium (

{NH}_{4}^{+}

), nitrite (

{NO}_{2}^{-}

), nitrate (

{NO}_{3}^{-}

), and molecular nitrogen (N 2 ) net flux rates were then measured in the light and in the dark in four replicate microcosms per condition. Details of the incubation procedures are reported in Soana et al (). Briefly, a short‐term (1–2 h) batch incubation started when a gas‐tight transparent lid was positioned on the top of each core.…”

Section: Methodsmentioning

confidence: 99%

“…We therefore assumed that the IPT is reliable in our system. Soana et al () demonstrated that in the Mincio River sediments the dissimilative nitrate reduction to ammonium (DNRA) was also a minor process. These authors demonstrated that denitrification of water column

{NO}_{3}^{-}

explained most of dark nitrate uptake by sediments and that denitrification was the dominant N sink.…”

Section: Methodsmentioning

confidence: 99%

“…They assimilate inorganic N from bottom and pore water, mainly as ammonium (

{NH}_{4}^{+}

), altering concentration gradients across the sediment–water interface (Soana et al ). They, also, release oxygen (O 2 ) and exudates at the interface or within sediments via the roots, increasing the volume of oxic sediments and favoring microbial processes such as ammonification, nitrification, and denitrification (Lemoine et al ; Soana et al ; Vila‐Costa et al ). Under N‐limiting conditions, primary producers may inhibit both dissimilative microbial processes and N‐losses from sediments while stimulating heterotrophic N‐fixation (Risgaard‐Petersen and Jensen ; Bartoli et al a ; McGlathery et al ).…”

mentioning

confidence: 99%

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Benthic N pathways in illuminated and bioturbated sediments studied with network analysis

Magri

Benelli

Bondavalli

et al. 2017

Limnology & Oceanography

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The regulation of benthic nitrogen (N) cycling by multiple interactions among bacteria, macrofauna, and primary producers is poorly understood. We hypothesized that a biodiverse benthic system should better exploit the benthic N‐availability and retain N than a simpler one. Retention occurs by avoiding losses both to the water column via increased recycling and to the atmosphere via decreased N2 fluxes and by limiting energy‐costly processes as N‐fixation. We also hypothesized that primary producer‐bacterial competition is reduced in the presence of macrofauna due to mobilization of refractory N pools. To this purpose, the effects of two bioturbators (the detritivorous Sparganophilus tamesis and the filter‐feeding Corbicula spp.) and two primary producer growth forms (the rooted macrophyte Vallisneria spiralis and microphytobenthos) on benthic N cycling were studied. An array of N‐processes were measured along a complexity gradient (from bare sediments to all combinations of the above mentioned organisms), and experimental outcomes were analyzed via ecological network analysis (ENA). This suite of algorithms, applied to the microscale, revealed differential partitioning of N fluxes among bare sediments (highest denitrification rates), sediments with macrofauna (highest recycling), and sediments with rooted plants (highest N‐fixation). N2 losses and inputs were significantly reduced when all components were represented, and N requirements by primary producers were to a large extent supported by the activity of macrofauna. Ecological interactions in biodiverse benthic systems promoted an efficient exploitation of sedimentary N pools, increased the coupling between recycling and uptake, and maximized N use efficiency at the expenses of losses and imports.

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Nitrate availability affects denitrification in Phragmites australis sediments

et al. 2020

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Understanding relationships between an increase in nitrate (NO3−) loading and the corresponding effects of wetland vegetation on denitrification is essential to designing, restoring, and managing wetlands and canals to maximize their effectiveness as buffers against eutrophication. Although Phragmites australis (Cav.) Trin. ex Steud. is frequently used to remediate nitrogen (N) pollution, no information is available on how NO3− concentration may affect plant‐mediated denitrification. In the present study, denitrification was measured in outdoor vegetated and unvegetated mesocosms incubated in both summer and winter. After spiking the mesocosms with NO3− concentrations typical of agricultural drainage water (0.7−11.2 mg N L−1), denitrification was quantified by the simultaneous measurement of NO3− consumption and dinitrogen gas (N2) production. Although denitrification rates varied with vegetation presence and season, NO3− availability exerted a significant positive effect on the process. Vegetated sediments were more efficient than bare sediments in adapting their mitigation potential to an increase in NO3−, by yielding a one‐order‐of‐magnitude increase in NO3− removal rates, under both summer (743−6007 mg N m−2 d−1) and winter (43−302 mg N m−2 d−1) conditions along the NO3− gradient. Denitrification was the dominant sink for water NO3− in winter and only for vegetated sediments in summer. Nitrification likely contributed to fuel denitrification in summer unvegetated sediments. Since denitrification rates followed Michaelis–Menten kinetics, P. australis‐mediated depuration may be considered optimal up to 5.0 mg N L−1. The present outcomes provide experimentally supported evidence that restoration with P. australis can work as a cost‐effective means of improving water quality in agricultural watersheds.

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Benthic nitrogen metabolism in a macrophyte meadow (Vallisneria spiralis L.) under increasing sedimentary organic matter loads

Cited by 35 publications

References 71 publications

Vegetated canals mitigate nitrogen surplus in agricultural watersheds

Vegetated canals mitigate nitrogen surplus in agricultural watersheds

Benthic N pathways in illuminated and bioturbated sediments studied with network analysis

Nitrate availability affects denitrification in Phragmites australis sediments

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