Determination of ultra‐low oxygen concentrations in oxygen minimum zones by the STOX sensor

Revsbech, Niels Peter; Larsen, Lars; Gundersen, Jens Kristïan; Dalsgaard, Tage; Ulloa, Osvaldo; Thamdrup, Bo

doi:10.4319/lom.2009.7.371

Cited by 245 publications

(284 citation statements)

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“…Dissolved oxygen concentration, as measured by the CTD oxygen sensor, decreased from fully saturated at the surface to o2.5 mM (that is, at the detection limit of the CTD oxygen sensor real oxygen concentrations are likely to be substantially lower; see Revsbech et al, 2009;Stolper et al, 2010) within the core of the OMZ and increased again with depth starting at 1050 m (Figure 1b). Sulfide was not detected, indicating the absence of euxinic conditions.…”

Section: Resultsmentioning

confidence: 99%

“…The copy numbers of archaeal 16S rDNA were estimated by using the 16S rDNA specific primers Parch519F and ARC915R (Coolen et al, 2004); Thaumarchaeota (MCG1) 16S rDNA with MCGI-391F and MCGI-554R primers as described by Coolen et al (2007); archaeal amoA with primers CrenAmoAQ-F and CrenAmoAModR (Mincer et al, 2007); and 16S rDNA anammox with Brod541F and Amx820R as described by Li et al (2010). For the quantification of the hzo gene, hzo primers hzo_LV2F and (Revsbech et al, 2009). Persian Gulf Water (PGW) and to a much lesser extent, Red Sea Water (RSW), influence the OMZ at our study site.…”

Section: Q-pcr Analysismentioning

confidence: 99%

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Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

et al. 2011

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Ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria have emerged as significant factors in the marine nitrogen cycle and are responsible for the oxidation of ammonium to nitrite and dinitrogen gas, respectively. Potential for an interaction between these groups exists; however, their distributions are rarely determined in tandem. Here we have examined the vertical distribution of AOA and anammox bacteria through the Arabian Sea oxygen minimum zone (OMZ), one of the most intense and vertically exaggerated OMZs in the global ocean, using a unique combination of intact polar lipid (IPL) and gene-based analyses, at both DNA and RNA levels. To screen for AOA-specific IPLs, we developed a high-performance liquid chromatography/mass spectrometry/mass spectrometry method targeting hexose-phosphohexose (HPH) crenarchaeol, a common IPL of cultivated AOA. HPH-crenarchaeol showed highest abundances in the upper OMZ transition zone at oxygen concentrations of ca. 5 lM, coincident with peaks in both thaumarchaeotal 16S rDNA and amoA gene abundances and gene expression. In contrast, concentrations of anammox-specific IPLs peaked within the core of the OMZ at 600 m, where oxygen reached the lowest concentrations, and coincided with peak anammox 16S rDNA and the hydrazine oxidoreductase (hzo) gene abundances and their expression. Taken together, the data reveal a unique depth distribution of abundant AOA and anammox bacteria and the segregation of their respective niches by 4400 m, suggesting no direct coupling of their metabolisms at the time and site of sampling in the Arabian Sea OMZ.

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Section: Resultsmentioning

confidence: 99%

Section: Q-pcr Analysismentioning

confidence: 99%

Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

et al. 2011

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“…The standard oxygen sensor of the conductivity-temperature-depth (Seabird) and an additionally mounted microsensor were used together to identify the OMZ. Besides, we deployed the highly sensitive STOX (Switchable Trace amount OXygen) sensor (Revsbech et al, 2009;detection (Figure 1). NH 4 þ and NO 2 À concentrations were measured immediately after sampling using fluorometric and spectrophotometric techniques, respectively (Grasshoff, 1983;Holmes et al, 1999).…”

Section: Methodsmentioning

confidence: 99%

Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium

et al. 2011

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A combination of stable isotopes ( 15 N) and molecular ecological approaches was used to investigate the vertical distribution and mechanisms of biological N 2 production along a transect from the Omani coast to the central-northeastern (NE) Arabian Sea. The Arabian Sea harbors the thickest oxygen minimum zone (OMZ) in the world's oceans, and is considered to be a major site of oceanic nitrogen (N) loss. Short (o48 h) anoxic incubations with 15 N-labeled substrates and functional gene expression analyses showed that the anammox process was highly active, whereas denitrification was hardly detectable in the OMZ over the Omani shelf at least at the time of our sampling. Anammox was coupled with dissimilatory nitrite reduction to ammonium (DNRA), resulting in the production of double-15 N-labeled N 2 from 15 NO 2 À , a signal often taken as the lone evidence for denitrification in the past. Although the central-NE Arabian Sea has conventionally been regarded as the primary N-loss region, low potential N-loss rates at sporadic depths were detected at best. N-loss activities in this region likely experience high spatiotemporal variabilities as linked to the availability of organic matter. Our finding of greater N-loss associated with the more productive Omani upwelling region is consistent with results from other major OMZs. The close reliance of anammox on DNRA also highlights the need to take into account the effects of coupling N-transformations on oceanic N-loss and subsequent N-balance estimates.

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“…However, we have no indication that Methylobacter possesses this trait, and nitrite was not detectable in another microcosm experiment with the same soil . Recently developed microelectrodes (Revsbech et al, 2009;Revsbech et al, 2011) have demonstrated nanomolar oxygen concentrations in areas that have been considered anoxic so far. However, the design of our microcosms includes a trap to remove any oxygen that might have diffused into the lower compartment (Murase and Frenzel, 2007).…”

Section: High-resolution Spatial Analysis Of Methanotrophs a Reim Et Almentioning

confidence: 99%

One millimetre makes the difference: high-resolution analysis of methane-oxidizing bacteria and their specific activity at the oxic–anoxic interface in a flooded paddy soil

et al. 2012

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Aerobic methane-oxidizing bacteria (MOB) use a restricted substrate range, yet >30 species-equivalent operational taxonomical units (OTUs) are found in one paddy soil. How these OTUs physically share their microhabitat is unknown. Here we highly resolved the vertical distribution of MOB and their activity. Using microcosms and cryosectioning, we sub-sampled the top 3-mm of a water-saturated soil at near in situ conditions in 100-μm steps. We assessed the community structure and activity using the particulate methane monooxygenase gene pmoA as a functional and phylogenetic marker by terminal restriction fragment length polymorphism (t-RFLP), a pmoA-specific diagnostic microarray, and cloning and sequencing. pmoA genes and transcripts were quantified using competitive reverse transcriptase PCR combined with t-RFLP. Only a subset of the methanotroph community was active. Oxygen microprofiles showed that 89% of total respiration was confined to a 0.67-mm-thick zone immediately above the oxic–anoxic interface, most probably driven by methane oxidation. In this zone, a Methylobacter-affiliated OTU was highly active with up to 18 pmoA transcripts per cell and seemed to be adapted to oxygen and methane concentrations in the micromolar range. Analysis of transcripts with a pmoA-specific microarray found a Methylosarcina-affiliated OTU associated with the surface zone. High oxygen but only nanomolar methane concentrations at the surface suggested an adaptation of this OTU to oligotrophic conditions. No transcripts of type II methanotrophs (Methylosinus, Methylocystis) were found, which indicated that this group was represented by resting stages only. Hence, different OTUs within a single guild shared the same microenvironment and exploited different niches.

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Determination of ultra‐low oxygen concentrations in oxygen minimum zones by the STOX sensor

Abstract: The methods used until now have not been able to reliably resolve O 2 concentrations in oceanic oxygen minimum zones below 1-2 µmol L -1

Cited by 245 publications

References 20 publications

Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium

One millimetre makes the difference: high-resolution analysis of methane-oxidizing bacteria and their specific activity at the oxic–anoxic interface in a flooded paddy soil

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