Oxygen minimum zones (OMZs) in the modern ocean

Paulmier, Aurélien; Ruiz‐Pino, Diana

doi:10.1016/j.pocean.2008.08.001

Cited by 667 publications

(549 citation statements)

References 47 publications

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“…The largest OMZs occur in areas of persistent nutrient upwelling, as in the Eastern Tropical North Pacific (ETNP) off Mexico (Karstensen et al, 2008). Encompassing~12 × 10 6 km 2 of shelf and off-shelf waters south of Baja California, the ETNP OMZ is the largest of the major permanent OMZs (41% of total OMZ area; Paulmier and Ruiz, 2009), with dissolved O 2 concentrations falling below the detection limit (o0.1 μM) at mid-water depths (~150-750 m; Cline and Richards, 1974;Tiano et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone

et al. 2015

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The genetic composition of marine microbial communities varies at the microscale between particleassociated (PA; 41.6 μm) and free-living (FL; 0.2-1.6 μm) niches. It remains unclear, however, how metabolic activities differ between PA and FL fractions. We combined rate measurements with metatranscriptomics to quantify PA and FL microbial activity in the oxygen minimum zone (OMZ) of the Eastern Tropical North Pacific, focusing on dissimilatory processes of the nitrogen (N) cycle. Bacterial gene counts were 8-to 15-fold higher in the FL compared with the PA fraction. However, rates of all measured N cycle processes, excluding ammonia oxidation, declined significantly following particle (41.6 μm) removal. Without particles, rates of nitrate reduction to nitrite (1.5-9.4 nM N d − 1 ) fell to zero and N 2 production by denitrification (0.5-1.7 nM N d − 1 ) and anammox (0.3-1.9 nM N d − 1 ) declined by 53-85%. The proportional representation of major microbial taxa and N cycle gene transcripts in metatranscriptomes followed fraction-specific trends. Transcripts encoding nitrate reductase were uniform among PA and FL fractions, whereas anammox-associated transcripts were proportionately enriched up to 15-fold in the FL fraction. In contrast, transcripts encoding enzymes for N 2 O and N 2 production by denitrification were enriched up to 28-fold in PA samples. These patterns suggest that the majority of N cycle activity, excluding N 2 O and N 2 production by denitrification, is confined to a FL majority that is critically dependent on access to particles, likely as a source of organic carbon and inorganic N. Variable particle distributions may drive heterogeneity in N cycle activity and gene expression in OMZs.

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Section: Introductionmentioning

confidence: 99%

Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone

et al. 2015

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“…This included depths were dissolved oxygen (DO) concentrations were extremely low, indicating that NO 2 À oxidation persists even under low DO. In fact, NO 2 À -based metabolism is central in the world's OMZs (Francis et al, 2007;Wright et al, 2012), where DO concentrations fall below 20 mM because of microbial respiration (Paulmier and Ruiz-Pino, 2009). The accumulation of NO 2 À within OMZs is a diagnostic of anaerobic N and sulfur cycling (Ulloa et al, 2012), and among the processes that use NO 2 À as an oxidant under these conditions, anammox and denitrification lead to gaseous N loss from the ocean (Lam and Kuypers, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The eastern tropical North Pacific Ocean (ETNP) is the largest oceanic OMZ (Paulmier and Ruiz-Pino, 2009), and so has an important role in oceanic-and global-N cycling. Annually, B26 Tg of dissolved N is converted to gaseous forms in the ETNP (DeVries et al, 2012) via microbial processes that require oxidized N. Our work and that of others has also identified relatively high rates of NH 3 oxidation in the ETNP (Ward and Zafiriou, 1988, Sutka et al, 2004, Beman et al, 2008); yet NO 2 À oxidation has not been previously measured in this region.…”

Section: Introductionmentioning

confidence: 99%

Nitrite oxidation in the upper water column and oxygen minimum zone of the eastern tropical North Pacific Ocean

2013

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Nitrogen (N) is an essential nutrient in the sea and its distribution is controlled by microorganisms. Within the N cycle, nitrite (NO 2 À ) has a central role because its intermediate redox state allows both oxidation and reduction, and so it may be used by several coupled and/or competing microbial processes. In the upper water column and oxygen minimum zone (OMZ) of the eastern tropical North Pacific Ocean (ETNP), we investigated aerobic NO 2 À oxidation, and its relationship to ammonia (NH 3 ) oxidation, using rate measurements, quantification of NO 2 À -oxidizing bacteria via quantitative PCR (QPCR), and pyrosequencing. 15 NO 2 À oxidation rates typically exhibited two subsurface maxima at six stations sampled: one located below the euphotic zone and beneath NH 3 oxidation rate maxima, and another within the OMZ. 15 NO 2 À oxidation rates were highest where dissolved oxygen concentrations were o5 lM, where NO 2 À accumulated, and when nitrate (NO 3 À ) reductase genes were expressed; they are likely sustained by NO 3 À reduction at these depths. QPCR and pyrosequencing data were strongly correlated (r 2 ¼ 0.79), and indicated that Nitrospina bacteria numbered up to 9.25% of bacterial communities. Different Nitrospina groups were distributed across different depth ranges, suggesting significant ecological diversity within Nitrospina as a whole. Across the data set, 15 NO 2 À oxidation rates were decoupled from 15 NH 4 þ oxidation rates, but correlated with Nitrospina (r 2 ¼ 0.246, Po0.05) and NO 2 À concentrations (r 2 ¼ 0.276, Po0.05). Our findings suggest that Nitrospina have a quantitatively important role in NO 2 À oxidation and N cycling in the ETNP, and provide new insight into their ecology and interactions with other N-cycling processes in this biogeochemically important region of the ocean.

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“…Its vertical distribution extends from approximately 150 to 1000 m below the sea surface with oxygen concentrations at times as low as 0.1 mM (Morrison et al, 1999;Paulmier and Ruiz-Pino, 2009), rendering it one of the most expansive and intense OMZs globally. N-cycling in the Arabian Sea may even impact the earth's climate due to OMZ intensity-related fluctuations in N-loss via heterotrophic denitrification Suthhof et al, 2001).…”

Section: Introductionmentioning

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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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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Oxygen minimum zones (OMZs) in the modern ocean

Cited by 667 publications

References 47 publications

Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone

Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone

Nitrite oxidation in the upper water column and oxygen minimum zone of the eastern tropical North Pacific Ocean

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

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