On the effect of low oxygen concentrations on bacterial degradation of sinking particles

Moigne, Frédéric A.C. Le; Cisternas-Novoa, Carolina; Piontek, Judith; Maßmig, Marie; Engel, Anja

doi:10.1038/s41598-017-16903-3

Cited by 33 publications

(35 citation statements)

References 68 publications

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“…Remineralization of organic matter under anoxia induces nitrogen (N)loss by denitrification and anammox as well as dissimilatory nitrate reduction to ammonium (DNRA) in the water column and sediments off the coast of Peru (Kalvelage et al, 2013;Arévalo-Martínez et al, 2015;Dale et al, 2016;Sommer et al, 2016;Glock et al, 2019). Although organic matter remineralization is classically assumed to be limited by the absence of oxygen (Demaison and Moore, 1980), recent studies report similar abilities of marine microbes to degrade organic matter in oxygenated surface waters and within OMZs (Pantoja et al, 2009;Maßmig et al, 2019a, b), suggesting that other factors, such as the quality of organic matter may regulate microbial activity within OMZs (Pantoja et al, 2009;Le Moigne et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Loginova¹,

Dale²,

Thomsen³

et al. 2020

Preprint

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Abstract. The eastern tropical South Pacific (ETSP) represents one of the most productive areas in the ocean that is characterized by a pronounced oxygen minimum zone (OMZ). Particulate organic matter (POM) that sinks out of the euphotic zone is supplied to the anoxic sediments and utilized by microbial communities. The degradation of POM is associated with dissolved organic matter (DOM) production and reworking. The release of recalcitrant DOM to the overlying waters may represent an important organic matter escape mechanism from remineralization within sediments but received little attention in OMZ regions so far. Here, we combine measurements of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) with DOM optical properties in the form of chromophoric (CDOM) and fluorescent (FDOM) DOM from pore waters and near-bottom waters of the ETSP off Peru. We evaluate diffusion&#8211;driven fluxes and net in situ fluxes of DOC and DON in order to investigate processes affecting DOM cycling at the sediment&#8211;water interface along a transect 12&#176;&#8201;S. To our knowledge, these are the first data for sediment release of DON and pore water CDOM and FDOM for the ETSP off Peru. Pore-water DOC and DON accumulated with increasing sediment depth, suggesting an imbalance between DOM production and remineralization within sediments. High DON accumulation resulted in very low pore water DOC&#8201;/&#8201;DON ratios (>&#8201;1) which could be caused by either an <q>imbalance</q> in DOC and DON remineralization, or to the presence of an additional nitrogen source. Diffusion driven fluxes of DOC and DON exhibited high spatial variability. They varied from 0.2&#8211;0.1&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 to 2.52&#8211;1.3&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 and from &#8722;0.042&#8211;0.02&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 to 3.32&#8211;1.7&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1, respectively. Generally low net in situ DOC and DON fluxes as well as steepening of spectral slope (S) of CDOM and accumulation of humic-like FDOM at the near-bottom waters over time indicated active microbial DOM utilization at the sediment&#8211;water interface, potentially stimulated by nitrate (NO3&#8722;) and nitrite (NO2&#8722;). The microbial DOC utilization rates, estimated in our study, may be sufficient to support denitrification rates of 0.2&#8211;1.4&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1, suggesting that sediment release of DOM contributes substantially to nitrogen loss processes in the ETSP off Peru.

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Section: Introductionmentioning

confidence: 99%

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Loginova¹,

Dale²,

Thomsen³

et al. 2020

Preprint

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“…− were also detected. Particulate organic carbon (POC) concentration was low in the blue hole when compared to the Baltic sea, indicating that the blue hole had a poor nutrient input 45 . The blue hole is ~7 km and 70 km from Jinqing Island and Yongxing Island, respectively, and ~400 km south of Sanya 42 .…”

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confidence: 99%

Microbial Diversity and Metabolic Potential in the Stratified Sansha Yongle Blue Hole in the South China Sea

Xie

Zhang

et al. 2020

Sci Rep

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The Sansha Yongle Blue Hole is the world's deepest (301 m) underwater cave and has a sharp redox gradient, with oligotrophic, anoxic, and sulfidic bottom seawater. In order to discover the microbial communities and their special biogeochemical pathways in the blue hole, we analyzed the 16S ribosomal RNA amplicons and metagenomes of microbials from seawater depths with prominent physical, chemical, and biological features. Redundancy analysis showed that dissolved oxygen was the most important factor affecting the microbial assemblages of the blue hole and surrounding open sea waters, and significantly explained 44.7% of the total variation, followed by silicate, temperature, sulfide, ammonium, methane, nitrous oxide, nitrate, dissolved organic carbon, salinity, particulate organic carbon, and chlorophyll a. We identified a bloom of Alteromonas (34.9%) at the primary nitrite maximum occurring in close proximity to the chlorophyll a peak in the blue hole. Genomic potential for nitrate reduction of Alteromonas might contribute to this maximum under oxygen decrease. Genes that would allow for aerobic ammonium oxidation, complete denitrification, and sulfuroxidization were enriched at nitrate/nitrite-sulfide transition zone (90 and 100 m) of the blue hole, but not anammox pathways. Moreover, γ-Proteobacterial clade SUP05, ε-Proteobacterial genera Sulfurimonas and Arcobacter, and Chlorobi harbored genes for sulfur-driven denitrification process that mediated nitrogen loss and sulfide removal. In the anoxic bottom seawater (100-300 m), high levels of sulfate reducers and dissimilatory sulfite reductase gene (dsrA) potentially created a sulfidic zone of ~200 m thickness. Our findings suggest that in the oligotrophic Sansha Yongle Blue Hole, o 2 deficiency promotes nitrogen-and sulfur-cycling processes mediated by metabolically versatile microbials. O 2-deficient regions occur throughout global oceans 1. Intermediate layers of the ocean develop O 2-deficient water masses, referred to as oxygen minimum zones (OMZs), due to limitation in photosynthetic O 2 production and high-level aerobic respiration during the degradation of surface-derived organics 2. In these OMZs, such as the Eastern Tropical South Pacific (ETSP) and the Arabian Sea, O 2 concentrations fall below sensor-specific detection limits 3-5. In contrast, the Peru Upwelling Region, the Namibian Shelf, and the Indian Continental Shelf experience episodic plumes of hydrogen sulfide (H 2 S) 6-8. These sulfidic environments are also found in enclosed or semi-enclosed basins, including the Black Sea Basin 9-12 , the Baltic Sea Basin 13-15 , the Cariaco Basin 16,17 , and submarine caves, such as the Bahamian blue holes 18 , the Belize Blue Hole 19 , and the Sansha Yongle Blue Hole 20. In O 2-deficient regions, microbial reactions control key steps in carbon, nitrogen, and sulfur transformation under successional redox gradients extending throughout the water column 21. NO 3 − is the most energetically

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“…The hypothesis that the potential expansion of anoxic and hypoxic OMZs will increase the efficiency with which POC is transported to the ocean's interior appears to be strengthening (e.g., Cavan et al, ; Engel et al, ; Le Moigne et al, ). However, inside the ETNA OMZ, the attenuation rates of net POC fluxes by small particles were significantly higher than those above the OMZ for 62% of the profiles (p < 0.05, paired t test, Figures ).…”

Section: Discussionmentioning

confidence: 99%

“…These regions appear to reduce POC remineralization rates allowing POC to reach deeper waters relative to oxygenated areas (O 2 > 120 μmol kg −1 , Cavan et al, 2017, Devol & Hartnett, 2001Engel et al, 2017;Martin et al, 1987;Roullier et al, 2014;Van Mooy et al, 2002). Thus, the hypothesis that the potential expansion of OMZs could increase the efficiency of the oceanic BCP is strengthening (e.g., Cavan et al, 2017;Deutsch et al, 2014;Engel et al, 2017;Le Moigne et al, 2017;Oschlies et al, 2019;Schmidtko et al, 2017;Stramma et al, 2008). However, this hypothesis is based on measurements of the attenuation rates of POC fluxes mostly due to large sinking particles because these are the predominant fraction of particles collected by conventional sediment traps (e.g., >100 μm; Arístegui et al, 2009;Buesseler et al, 2007;Devol & Hartnett, 2001;Engel et al, 2017;Gardner et al, 1985;Martin et al, 1987;Trull et al, 2008;Van Mooy et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Do Oceanic Hypoxic Regions Act as Barriers for Sinking Particles? A Case Study in the Eastern Tropical North Atlantic

Rasse

Dall’Olmo

2019

Global Biogeochemical Cycles

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In oxygen minimum zones (OMZs), the attenuation rates of particulate organic carbon (POC) fluxes of large particles are known to be reduced, thus increasing the efficiency with which the biological carbon pump (BCP) transfers carbon to the abyss. The BCP efficiency is expected to further increase if OMZs expand. However, little is known about how the POC fluxes of small particles—a significant component of the BCP—are attenuated inside OMZs. In this study, data collected by two BGC‐Argo floats deployed in the hypoxic OMZ of the eastern tropical North Atlantic were used to estimate net instantaneous fluxes of POC via small particle during 3 years. This information was analyzed together with meteorological data and published POC fluxes of large particles and allowed us to conclude that (1) major pulses of surface‐derived small particles toward the OMZ interior coincided with seasonal changes in wind stress and precipitation; (2) a permanent layer of small particles, presumably linked to microbial communities, was found in the upper section of the OMZ which might play a key role attenuating POC fluxes; and (3) fluxes of large particles were attenuated less efficiently inside this poorly oxygenated region than above it, while attenuation of small‐particle fluxes were equivalent or significantly higher inside the OMZ. These results highlight that more information about the processes controlling the fluxes of small and large particles in hypoxic OMZs is needed to better understand the impact of hypoxic OMZs on the BCP efficiency.

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On the effect of low oxygen concentrations on bacterial degradation of sinking particles

Cited by 33 publications

References 68 publications

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Sediment release of dissolved organic matter to the oxygen minimum zone off Peru

Microbial Diversity and Metabolic Potential in the Stratified Sansha Yongle Blue Hole in the South China Sea

Do Oceanic Hypoxic Regions Act as Barriers for Sinking Particles? A Case Study in the Eastern Tropical North Atlantic

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