scholarly journals Substantial oxygen consumption by aerobic nitrite oxidation in oceanic oxygen minimum zones

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J. M. Beman ◽  
S. M. Vargas ◽  
J. M. Wilson ◽  
E. Perez-Coronel ◽  
J. S. Karolewski ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Nitrate Reduction ◽  
Oxygen Affinity ◽  
Nitrite Oxidation ◽  
Oxygen Minimum Zones ◽  
Oxidation Rates ◽  
Consumption Rates ◽  
High Oxygen Affinity ◽  
Omic Data ◽  
Oxygen Minimum

AbstractOceanic oxygen minimum zones (OMZs) are globally significant sites of biogeochemical cycling where microorganisms deplete dissolved oxygen (DO) to concentrations <20 µM. Amid intense competition for DO in these metabolically challenging environments, aerobic nitrite oxidation may consume significant amounts of DO and help maintain low DO concentrations, but this remains unquantified. Using parallel measurements of oxygen consumption rates and 15N-nitrite oxidation rates applied to both water column profiles and oxygen manipulation experiments, we show that the contribution of nitrite oxidation to overall DO consumption systematically increases as DO declines below 2 µM. Nitrite oxidation can account for all DO consumption only under DO concentrations <393 nM found in and below the secondary chlorophyll maximum. These patterns are consistent across sampling stations and experiments, reflecting coupling between nitrate reduction and nitrite-oxidizing Nitrospina with high oxygen affinity (based on isotopic and omic data). Collectively our results demonstrate that nitrite oxidation plays a pivotal role in the maintenance and biogeochemical dynamics of OMZs.

scholarly journals Constraining oxygen consumption by nitrite oxidation in oceanic oxygen minimum zones

2020 ◽  
Author(s):  
J.M. Beman ◽  
S.M. Vargas ◽  
J.M. Wilson ◽  
E. Perez-Coronel ◽  
S. Vazquez ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
North Pacific Ocean ◽  
Low Oxygen ◽  
Nitrite Oxidation ◽  
Oxygen Minimum Zones ◽  
Oxidation Rates ◽  
Low Levels ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

AbstractOceanic oxygen minimum zones (OMZs) occur where microorganisms deplete dissolved oxygen (DO) to exceptionally low levels, and are globally significant sites of biogeochemical cycling. Amid the intense competition for DO and other substrates occurring in these metabolically challenging environments, aerobic nitrite oxidation may consume significant amounts of DO, but this has not been examined comprehensively. Using parallel measurements of oxygen consumption rates and 15N-nitrite oxidation rates applied to water column profiles and to oxygen manipulation experiments, we show that nitrite oxidation is a substantial sink for DO in the ocean’s largest OMZ. The contribution of nitrite oxidation to overall DO consumption increased at low DO concentrations, tracking gradients and variations within and across multiple stations in the eastern tropical North Pacific Ocean. Oxygen manipulation experiments produced highly consistent effects, with nitrite oxidation responsible for progressively more DO consumption (up to 97%) as DO was experimentally decreased. Natural abundance stable isotope data indicated coupling of nitrite oxidation and nitrate reduction, while 16S rRNA and metagenome sequencing revealed that Nitrospina ecotypes possessing high-affinity cytochrome oxidase genes were prevalent and active within the OMZ. Collectively, our results demonstrate that nitrite oxidation consumes significant amounts of DO, and that this proportion increases as DO declines—indicating that nitrite oxidation is critically important to the formation and maintenance of OMZs.SignificanceOceanic oxygen minimum zones (OMZs) are naturally-occuring regions of low oxygen found in select areas of the ocean. Lack of dissolved oxygen has important implications for both the distribution of marine organisms and global biogeochemical cycles, yet we have a limited understanding of how oxygen is depleted to such low levels. Here we comprehensively quantify the contribution of nitrite oxidation to oxygen depletion in the ocean’s largest OMZ. We observed highly consistent patterns across depth profiles, and in multiple experiments where we manipulated oxygen concentrations, finding that nitrite oxidation consumes progressively more oxygen at lower oxygen concentrations. Our findings demonstrate that nitrite oxidation plays a pivotal role in exhausting oxygen to the low levels found in OMZs.

scholarly journals Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters

2016 ◽  
Vol 113 (38) ◽  
pp. 10601-10606 ◽  
Author(s):  
Laura A. Bristow ◽  
Tage Dalsgaard ◽  
Laura Tiano ◽  
Daniel B. Mills ◽  
Anthony D. Bertagnolli ◽  
...  
Keyword(s):  
Nitrogen Loss ◽  
Strong Dependence ◽  
Ammonium Oxidation ◽  
Nitrite Oxidation ◽  
Fixed Nitrogen ◽  
Oxygen Minimum Zones ◽  
Oxidation Rates ◽  
Minimum Zone ◽  
Nanomolar Range ◽  
Oxygen Minimum

A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2concentrations present in the OMZ core (<10 nmol⋅L−1) is therefore essential for understanding and modeling nitrogen loss in OMZs. We determined rates of ammonium and nitrite oxidation in the seasonal OMZ off Concepcion, Chile at manipulated O2levels between 5 nmol⋅L−1and 20 μmol⋅L−1. Rates of both processes were detectable in the low nanomolar range (5–33 nmol⋅L−1O2), but demonstrated a strong dependence on O2concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L−1O2for ammonium oxidation and 778 ± 168 nmol⋅L−1O2for nitrite oxidation assuming one-component Michaelis–Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis–Menten model, indicating a high-affinity component with aKmof just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss.

scholarly journals The metabolic response of pteropods to acidification reflects natural CO<sub>2</sub>-exposure in oxygen minimum zones

2012 ◽  
Vol 9 (2) ◽  
pp. 747-757 ◽  
Author(s):  
A. E. Maas ◽  
K. F. Wishner ◽  
B. A. Seibel
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Ocean Acidification ◽  
Metabolic Response ◽  
Ammonia Excretion ◽  
Individual Species ◽  
Tropical Regions ◽  
Oxygen Minimum Zones ◽  
The Pacific ◽  
Oxygen Minimum

Abstract. Shelled pteropods (Thecosomata) are a group of holoplanktonic mollusks that are believed to be especially sensitive to ocean acidification because their aragonitic shells are highly soluble. Despite this concern, there is very little known about the physiological response of these animals to conditions of elevated carbon dioxide. This study examines the oxygen consumption and ammonia excretion of five pteropod species, collected from tropical regions of the Pacific Ocean, to elevated levels of carbon dioxide (0.10%, 1000 ppm). Our results show that pteropods that naturally migrate into oxygen minimum zones, such as Hyalocylis striata, Clio pyramidata, Cavolinia longirostris and Creseis virgula, were not affected by carbon dioxide at the levels and duration tested. Diacria quadridentata, which does not migrate, responds to high carbon dioxide conditions with reduced oxygen consumption and ammonia excretion. This indicates that the natural chemical environment of individual species may influence their resilience to ocean acidification.

scholarly journals Correction: Microbial niche differentiation explains nitrite oxidation in marine oxygen minimum zones

2021 ◽  
Author(s):  
Xin Sun ◽  
Claudia Frey ◽  
Emilio Garcia-Robledo ◽  
Amal Jayakumar ◽  
Bess B. Ward
Keyword(s):  
Niche Differentiation ◽  
Nitrite Oxidation ◽  
Oxygen Minimum Zones ◽  
Oxygen Minimum

scholarly journals On the role of circulation and mixing in the ventilation of oxygen minimum zones with a focus on the eastern tropical North Atlantic

2014 ◽  
Vol 11 (8) ◽  
pp. 12069-12136 ◽  
Author(s):  
P. Brandt ◽  
D. Banyte ◽  
M. Dengler ◽  
S.-H. Didwischus ◽  
T. Fischer ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Oxygen Supply ◽  
Oxygen Minimum Zones ◽  
Oxygen Budget ◽  
Tropical North Atlantic ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

Abstract. Ocean observations carried out in the framework of the Collaborative Research Center 754 (SFB 754) "Climate-Biogeochemistry Interactions in the Tropical Ocean" are used to study (1) the structure of tropical oxygen minimum zones (OMZs), (2) the processes that contribute to the oxygen budget, and (3) long-term changes in the oxygen distribution. The OMZ of the eastern tropical North Atlantic (ETNA), located between the well-ventilated subtropical gyre and the equatorial oxygen maximum, is composed of a deep OMZ at about 400 m depth with its core region centred at about 20° W, 10° N and a shallow OMZ at about 100 m depth with lowest oxygen concentrations in proximity to the coastal upwelling region off Mauritania and Senegal. The oxygen budget of the deep OMZ is given by oxygen consumption mainly balanced by the oxygen supply due to meridional eddy fluxes (about 60%) and vertical mixing (about 20%, locally up to 30%). Advection by zonal jets is crucial for the establishment of the equatorial oxygen maximum. In the latitude range of the deep OMZ, it dominates the oxygen supply in the upper 300 to 400 m and generates the intermediate oxygen maximum between deep and shallow OMZs. Water mass ages from transient tracers indicate substantially older water masses in the core of the deep OMZ (about 120–180 years) compared to regions north and south of it. The deoxygenation of the ETNA OMZ during recent decades suggests a substantial imbalance in the oxygen budget: about 10% of the oxygen consumption during that period was not balanced by ventilation. Long-term oxygen observations show variability on interannual, decadal and multidecadal time scales that can partly be attributed to circulation changes. In comparison to the ETNA OMZ the eastern tropical South Pacific OMZ shows a similar structure including an equatorial oxygen maximum driven by zonal advection, but overall much lower oxygen concentrations approaching zero in extended regions. As the shape of the OMZs is set by ocean circulation, the widespread misrepresentation of the intermediate circulation in ocean circulation models substantially contributes to their oxygen bias, which might have significant impacts on predictions of future oxygen levels.

scholarly journals On the role of circulation and mixing in the ventilation of oxygen minimum zones with a focus on the eastern tropical North Atlantic

2015 ◽  
Vol 12 (2) ◽  
pp. 489-512 ◽  
Author(s):  
P. Brandt ◽  
H. W. Bange ◽  
D. Banyte ◽  
M. Dengler ◽  
S.-H. Didwischus ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Oxygen Supply ◽  
Oxygen Minimum Zones ◽  
Oxygen Budget ◽  
Tropical North Atlantic ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

Abstract. Ocean observations are analysed in the framework of Collaborative Research Center 754 (SFB 754) "Climate-Biogeochemistry Interactions in the Tropical Ocean" to study (1) the structure of tropical oxygen minimum zones (OMZs), (2) the processes that contribute to the oxygen budget, and (3) long-term changes in the oxygen distribution. The OMZ of the eastern tropical North Atlantic (ETNA), located between the well-ventilated subtropical gyre and the equatorial oxygen maximum, is composed of a deep OMZ at about 400 m in depth with its core region centred at about 20° W, 10° N and a shallow OMZ at about 100 m in depth, with the lowest oxygen concentrations in proximity to the coastal upwelling region off Mauritania and Senegal. The oxygen budget of the deep OMZ is given by oxygen consumption mainly balanced by the oxygen supply due to meridional eddy fluxes (about 60%) and vertical mixing (about 20%, locally up to 30%). Advection by zonal jets is crucial for the establishment of the equatorial oxygen maximum. In the latitude range of the deep OMZ, it dominates the oxygen supply in the upper 300 to 400 m and generates the intermediate oxygen maximum between deep and shallow OMZs. Water mass ages from transient tracers indicate substantially older water masses in the core of the deep OMZ (about 120–180 years) compared to regions north and south of it. The deoxygenation of the ETNA OMZ during recent decades suggests a substantial imbalance in the oxygen budget: about 10% of the oxygen consumption during that period was not balanced by ventilation. Long-term oxygen observations show variability on interannual, decadal and multidecadal timescales that can partly be attributed to circulation changes. In comparison to the ETNA OMZ, the eastern tropical South Pacific OMZ shows a similar structure, including an equatorial oxygen maximum driven by zonal advection but overall much lower oxygen concentrations approaching zero in extended regions. As the shape of the OMZs is set by ocean circulation, the widespread misrepresentation of the intermediate circulation in ocean circulation models substantially contributes to their oxygen bias, which might have significant impacts on predictions of future oxygen levels.

scholarly journals The metabolic response of pteropods to ocean acidification reflects natural CO<sub>2</sub>-exposure in oxygen minimum zones

2011 ◽  
Vol 8 (5) ◽  
pp. 10295-10316 ◽  
Author(s):  
A. E. Maas ◽  
K. F. Wishner ◽  
B. A. Seibel
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Ocean Acidification ◽  
Metabolic Response ◽  
Ammonia Excretion ◽  
Individual Species ◽  
Tropical Regions ◽  
Oxygen Minimum Zones ◽  
The Pacific ◽  
Oxygen Minimum

Abstract. Shelled pteropods (Thecosomata) are a group of holoplanktonic mollusks that are believed to be especially sensitive to ocean acidification because their aragonitic shells are highly soluble. Despite this concern, there is very little known about the physiological response of these animals to conditions of elevated carbon dioxide. This study examines the oxygen consumption and ammonia excretion of five pteropod species, collected from tropical regions of the Pacific Ocean, to elevated levels of carbon dioxide (0.10%, 1000 ppm). Our results show that pteropods that naturally migrate into oxygen minimum zones, such as Hyalocylis striata, Clio pyramidata, Cavolinia longirostris and Creseis virgula, were not affected by carbon dioxide at the levels and duration tested. Diacria quadridentata, which does not migrate, responds to high carbon dioxide conditions with reduced oxygen consumption and ammonia excretion. This indicates that the natural chemical environment of individual species influences their resilience to ocean acidification.

The formation of a metalimnetic oxygen minimum exemplifies how ecosystem dynamics shape biogeochemical processes: A modelling study

2020 ◽  
Author(s):  
Chenxi Mi ◽  
Tom Shatwell ◽  
Karsten Rinke
Keyword(s):  
Water Quality ◽  
Oxygen Consumption ◽  
Water Temperature ◽  
Community Dynamics ◽  
Decisive Role ◽  
Ecosystem Dynamics ◽  
Algal Community ◽  
Quality Model ◽  
Consumption Rates ◽  
Oxygen Minimum

&lt;p&gt;Metalimnetic oxygen minima are observed in many lakes and reservoirs, but the mechanisms behind this phenomenon are not well understood. Thus, we simulated the metalimnetic oxygen minimum (MOM) in the Rappbode Reservoir (Germany) with a well-established two-dimensional water quality model (CE-QUAL-W2) to systematically quantify the chain of events leading to its formation. We used high-resolution measured data to calibrate the model, which accurately reproduced the physical (e.g. water level and water temperature), biogeochemical (e.g. nutrient and oxygen dynamics) and ecological (e.g. algal community dynamics) features of the reservoir, particularly the spatial and temporal extent of the MOM. The results indicated that around 60%&amp;#160;of the total oxygen consumption rate in the MOM layer originated from benthic processes whereas the remainder originated from pelagic processes. The occurrence of the cyanobacterium Planktothrix rubescens in the metalimnion delayed and slightly weakened the MOM through photosynthesis, although its decaying biomass ultimately induced the MOM. Our research also confirmed the decisive role of water temperature in the formation of the MOM since the water temperatures, and thus benthic and pelagic oxygen consumption rates, were higher in the metalimnion than in the hypolimnion. Our model is not only providing novel conclusions about the drivers of MOM development and their quantitative contributions, it is also a new tool for understanding and predicting ecological and biogeochemical water quality dynamics.&lt;/p&gt;

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