Effect of settled diatom-aggregates on benthic nitrogen cycling

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Resumé

The marine sediment hosts a mosaic of microhabitats. Recently it has been demonstrated that the settlement of phycodetrital aggregates can induce local changes in the benthic O 2 distribution due to confined enrichment of organic material and alteration of the diffusional transport. Here, we show how this microscale O 2 shift substantially affects benthic nitrogen cycling. In sediment incubations, the settlement of diatom-aggregates markedly enhanced benthic O 2 and NO - 3 consumption and stimulated NO - 2 and NH + 4 production. Oxygen microprofiles revealed the rapid development of anoxic niches within and underneath the aggregates. During 120 h following the settling of the aggregates, denitrification of NO - 3 from the overlying water increased from 13.5 μmol m −2 h −1 to 24.3 μmol m −2 h −1, as quantified by 15N enrichment experiment. Simultaneously, N 2 production from coupled nitrification-denitrification decreased from 33.4 μmol m −2 h −1 to 25.9 μmol m −2 h −1, probably due to temporary inhibition of the benthic nitrifying community. The two effects were of similar magnitude and left the total N 2 production almost unaltered. At the aggregate surface, nitrification was, conversely, very efficient in oxidizing NH + 4 liberated by mineralization of the aggregates. The produced NO - 3 was preferentially released into the overlying water and only a minor fraction contributed to denitrification activity. Overall, our data indicate that the abrupt change in O 2 microdistribution caused by aggregates stimulates denitrification of NO - 3 from the overlying water, and loosens the coupling between benthic nitrification and denitrification both in time and space. The study contributes to expanding the conceptual and quantitative understanding of how nitrogen cycling is regulated in dynamic benthic environments.

OriginalsprogEngelsk
TidsskriftLimnology and Oceanography
Vol/bind63
Udgave nummer1
Sider (fra-til)431-444
ISSN0024-3590
DOI
StatusUdgivet - jan. 2018

Fingeraftryk

Bacillariophyceae
denitrification
diatom
nitrification
nitrogen
benthic zone
water
marine sediments
benthic environment
space and time
microhabitats
mineralization
niches
effect
microhabitat
oxygen
marine sediment
sediments
niche
incubation

Citer dette

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title = "Effect of settled diatom-aggregates on benthic nitrogen cycling",
abstract = "The marine sediment hosts a mosaic of microhabitats. Recently it has been demonstrated that the settlement of phycodetrital aggregates can induce local changes in the benthic O 2 distribution due to confined enrichment of organic material and alteration of the diffusional transport. Here, we show how this microscale O 2 shift substantially affects benthic nitrogen cycling. In sediment incubations, the settlement of diatom-aggregates markedly enhanced benthic O 2 and NO - 3 consumption and stimulated NO - 2 and NH + 4 production. Oxygen microprofiles revealed the rapid development of anoxic niches within and underneath the aggregates. During 120 h following the settling of the aggregates, denitrification of NO - 3 from the overlying water increased from 13.5 μmol m −2 h −1 to 24.3 μmol m −2 h −1, as quantified by 15N enrichment experiment. Simultaneously, N 2 production from coupled nitrification-denitrification decreased from 33.4 μmol m −2 h −1 to 25.9 μmol m −2 h −1, probably due to temporary inhibition of the benthic nitrifying community. The two effects were of similar magnitude and left the total N 2 production almost unaltered. At the aggregate surface, nitrification was, conversely, very efficient in oxidizing NH + 4 liberated by mineralization of the aggregates. The produced NO - 3 was preferentially released into the overlying water and only a minor fraction contributed to denitrification activity. Overall, our data indicate that the abrupt change in O 2 microdistribution caused by aggregates stimulates denitrification of NO - 3 from the overlying water, and loosens the coupling between benthic nitrification and denitrification both in time and space. The study contributes to expanding the conceptual and quantitative understanding of how nitrogen cycling is regulated in dynamic benthic environments.",
author = "Ugo Marzocchi and Bo Thamdrup and Peter Stief and Glud, {Ronnie N.}",
year = "2018",
month = "1",
doi = "10.1002/lno.10641",
language = "English",
volume = "63",
pages = "431--444",
journal = "Limnology and Oceanography",
issn = "0024-3590",
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Effect of settled diatom-aggregates on benthic nitrogen cycling. / Marzocchi, Ugo; Thamdrup, Bo; Stief, Peter; Glud, Ronnie N.

I: Limnology and Oceanography, Bind 63, Nr. 1, 01.2018, s. 431-444.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Effect of settled diatom-aggregates on benthic nitrogen cycling

AU - Marzocchi, Ugo

AU - Thamdrup, Bo

AU - Stief, Peter

AU - Glud, Ronnie N.

PY - 2018/1

Y1 - 2018/1

N2 - The marine sediment hosts a mosaic of microhabitats. Recently it has been demonstrated that the settlement of phycodetrital aggregates can induce local changes in the benthic O 2 distribution due to confined enrichment of organic material and alteration of the diffusional transport. Here, we show how this microscale O 2 shift substantially affects benthic nitrogen cycling. In sediment incubations, the settlement of diatom-aggregates markedly enhanced benthic O 2 and NO - 3 consumption and stimulated NO - 2 and NH + 4 production. Oxygen microprofiles revealed the rapid development of anoxic niches within and underneath the aggregates. During 120 h following the settling of the aggregates, denitrification of NO - 3 from the overlying water increased from 13.5 μmol m −2 h −1 to 24.3 μmol m −2 h −1, as quantified by 15N enrichment experiment. Simultaneously, N 2 production from coupled nitrification-denitrification decreased from 33.4 μmol m −2 h −1 to 25.9 μmol m −2 h −1, probably due to temporary inhibition of the benthic nitrifying community. The two effects were of similar magnitude and left the total N 2 production almost unaltered. At the aggregate surface, nitrification was, conversely, very efficient in oxidizing NH + 4 liberated by mineralization of the aggregates. The produced NO - 3 was preferentially released into the overlying water and only a minor fraction contributed to denitrification activity. Overall, our data indicate that the abrupt change in O 2 microdistribution caused by aggregates stimulates denitrification of NO - 3 from the overlying water, and loosens the coupling between benthic nitrification and denitrification both in time and space. The study contributes to expanding the conceptual and quantitative understanding of how nitrogen cycling is regulated in dynamic benthic environments.

AB - The marine sediment hosts a mosaic of microhabitats. Recently it has been demonstrated that the settlement of phycodetrital aggregates can induce local changes in the benthic O 2 distribution due to confined enrichment of organic material and alteration of the diffusional transport. Here, we show how this microscale O 2 shift substantially affects benthic nitrogen cycling. In sediment incubations, the settlement of diatom-aggregates markedly enhanced benthic O 2 and NO - 3 consumption and stimulated NO - 2 and NH + 4 production. Oxygen microprofiles revealed the rapid development of anoxic niches within and underneath the aggregates. During 120 h following the settling of the aggregates, denitrification of NO - 3 from the overlying water increased from 13.5 μmol m −2 h −1 to 24.3 μmol m −2 h −1, as quantified by 15N enrichment experiment. Simultaneously, N 2 production from coupled nitrification-denitrification decreased from 33.4 μmol m −2 h −1 to 25.9 μmol m −2 h −1, probably due to temporary inhibition of the benthic nitrifying community. The two effects were of similar magnitude and left the total N 2 production almost unaltered. At the aggregate surface, nitrification was, conversely, very efficient in oxidizing NH + 4 liberated by mineralization of the aggregates. The produced NO - 3 was preferentially released into the overlying water and only a minor fraction contributed to denitrification activity. Overall, our data indicate that the abrupt change in O 2 microdistribution caused by aggregates stimulates denitrification of NO - 3 from the overlying water, and loosens the coupling between benthic nitrification and denitrification both in time and space. The study contributes to expanding the conceptual and quantitative understanding of how nitrogen cycling is regulated in dynamic benthic environments.

U2 - 10.1002/lno.10641

DO - 10.1002/lno.10641

M3 - Journal article

VL - 63

SP - 431

EP - 444

JO - Limnology and Oceanography

JF - Limnology and Oceanography

SN - 0024-3590

IS - 1

ER -