Articles | Volume 17, issue 3
Biogeosciences, 17, 813–831, 2020
https://doi.org/10.5194/bg-17-813-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue: Ocean deoxygenation: drivers and consequences – past, present...
Biogeosciences, 17, 813–831, 2020
https://doi.org/10.5194/bg-17-813-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
17 Feb 2020
Research article
| 17 Feb 2020
Trends and decadal oscillations of oxygen and nutrients at 50 to 300 m depth in the equatorial and North Pacific
Lothar Stramma et al.
Related authors
Lothar Stramma and Sunke Schmidtko
Ocean Sci., 17, 833–847, https://doi.org/10.5194/os-17-833-2021, https://doi.org/10.5194/os-17-833-2021, 2021
Short summary
Short summary
Six tropical areas in the Pacific, Atlantic and Indian oceans were investigated for trends for the years since 1950 for temperature, salinity, oxygen and nutrients at 50 to 300 m and 300 to 700 m depth. Generally, temperature increases, oxygen decreases and nutrients often increase. Overlain variability on the trends seem to be related to climate modes. Different trends indicate that oxygen and nutrient trends cannot by completely explained by local warming.
Yonss Saranga José, Lothar Stramma, Sunke Schmidtko, and Andreas Oschlies
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-155, https://doi.org/10.5194/bg-2019-155, 2019
Revised manuscript accepted for BG
Short summary
Short summary
In situ observations along the Peruvian and Chilean coasts have exhibited variability in the water column oxygen concentration. This variability, which is attributed to the El Niño Southern Oscillation (ENSO), might have implication on the vertical extension of the Eastern Tropical South Pacific (ETSP) oxygen minimum zone. Here using a coupled physical-biogeochemical model, we provide new insights into how ENSO variability affects the vertical extension of the oxygen-poor waters of the ETSP.
Rena Czeschel, Florian Schütte, Robert A. Weller, and Lothar Stramma
Ocean Sci., 14, 731–750, https://doi.org/10.5194/os-14-731-2018, https://doi.org/10.5194/os-14-731-2018, 2018
Short summary
Short summary
The mean circulation on the poleward side of the oxygen minimum zone is overlain by eddy activity playing an important role in the distribution of water masses and oxygen within the OMZ. The activity of different types of eddies was investigated during their westward propagation from the formation area off Peru/Chile into the open ocean. The focus was on the development of eddies, seasonal conditions during their formation, and the change of water mass properties transported within the eddies.
Lothar Stramma, Tim Fischer, Damian S. Grundle, Gerd Krahmann, Hermann W. Bange, and Christa A. Marandino
Ocean Sci., 12, 861–873, https://doi.org/10.5194/os-12-861-2016, https://doi.org/10.5194/os-12-861-2016, 2016
Short summary
Short summary
Results from a research cruise on R/V Sonne to the eastern tropical Pacific in October 2015 during the 2015–2016 El Niño show the transition of current, hydrographic, and nutrient conditions to El Niño conditions in the eastern tropical Pacific in October 2015. Although in early 2015 the El Niño was strong and in October 2015 showed a clear El Niño influence on the EUC, in the eastern tropical Pacific the measurements only showed developing El Niño water mass distributions.
Damian L. Arévalo-Martínez, Annette Kock, Carolin R. Löscher, Ruth A. Schmitz, Lothar Stramma, and Hermann W. Bange
Biogeosciences, 13, 1105–1118, https://doi.org/10.5194/bg-13-1105-2016, https://doi.org/10.5194/bg-13-1105-2016, 2016
Short summary
Short summary
We present the first measurements of N2O across three mesoscale eddies in the eastern tropical South Pacific. Eddie's vertical structure, offshore transport, properties during its formation and near-surface primary production determined the N2O distribution. Substantial depletion of N2O within the core of anticyclonic eddies suggests that although these are transient features, N-loss processes within their centres can lead to an enhanced N2O sink which is not accounted for in marine N2O budgets.
L. Stramma, R. Czeschel, T. Tanhua, P. Brandt, M. Visbeck, and B. S. Giese
Ocean Sci., 12, 153–167, https://doi.org/10.5194/os-12-153-2016, https://doi.org/10.5194/os-12-153-2016, 2016
Short summary
Short summary
The subsurface circulation in the eastern tropical North Atlantic OMZ is derived from velocity, float and tracer data and data assimilation results, and shows a cyclonic flow around the Guinea Dome reaching into the oxygen minimum zone. The stronger cyclonic flow around the Guinea Dome in 2009 seem to be connected to a strong Atlantic Meridional Mode (AMM) event.
A continuous deoxygenation trend of the low oxygen layer was confirmed.
Eddy influence is weak south of the Cape Verde Islands.
R. Czeschel, L. Stramma, R. A. Weller, and T. Fischer
Ocean Sci., 11, 455–470, https://doi.org/10.5194/os-11-455-2015, https://doi.org/10.5194/os-11-455-2015, 2015
Short summary
Short summary
Mean circulation in the eastern tropical South Pacific in 50-600m depth is modified by seasonal variability and eddies on the poleward side of the oxygen minimum zone(OMZ). Floats with parking depth at 400m show westward flow in the equatorial channel, sluggish flow in the northern part of the OMZ, and passage of eddies with oxygen anomalies. Net community production rates were estimated from a float. Oxygen decrease in 50-300m depth since 1976 is related to an increase in nitrate and phosphate.
P. Brandt, H. W. Bange, D. Banyte, M. Dengler, S.-H. Didwischus, T. Fischer, R. J. Greatbatch, J. Hahn, T. Kanzow, J. Karstensen, A. Körtzinger, G. Krahmann, S. Schmidtko, L. Stramma, T. Tanhua, and M. Visbeck
Biogeosciences, 12, 489–512, https://doi.org/10.5194/bg-12-489-2015, https://doi.org/10.5194/bg-12-489-2015, 2015
Short summary
Short summary
Our observational study looks at the structure of the eastern tropical North Atlantic (ETNA) oxygen minimum zone (OMZ) in comparison with the less-ventilated, eastern tropical South Pacific OMZ. We quantify the OMZ’s oxygen budget composed of consumption, advection, lateral and vertical mixing. Substantial oxygen variability is observed on interannual to multidecadal timescales. The deoxygenation of the ETNA OMZ during the last decades represents a substantial imbalance of the oxygen budget.
L. Stramma, H. W. Bange, R. Czeschel, A. Lorenzo, and M. Frank
Biogeosciences, 10, 7293–7306, https://doi.org/10.5194/bg-10-7293-2013, https://doi.org/10.5194/bg-10-7293-2013, 2013
P. J. Llanillo, J. Karstensen, J. L. Pelegrí, and L. Stramma
Biogeosciences, 10, 6339–6355, https://doi.org/10.5194/bg-10-6339-2013, https://doi.org/10.5194/bg-10-6339-2013, 2013
Lothar Stramma and Sunke Schmidtko
Ocean Sci., 17, 833–847, https://doi.org/10.5194/os-17-833-2021, https://doi.org/10.5194/os-17-833-2021, 2021
Short summary
Short summary
Six tropical areas in the Pacific, Atlantic and Indian oceans were investigated for trends for the years since 1950 for temperature, salinity, oxygen and nutrients at 50 to 300 m and 300 to 700 m depth. Generally, temperature increases, oxygen decreases and nutrients often increase. Overlain variability on the trends seem to be related to climate modes. Different trends indicate that oxygen and nutrient trends cannot by completely explained by local warming.
Yonss Saranga José, Lothar Stramma, Sunke Schmidtko, and Andreas Oschlies
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-155, https://doi.org/10.5194/bg-2019-155, 2019
Revised manuscript accepted for BG
Short summary
Short summary
In situ observations along the Peruvian and Chilean coasts have exhibited variability in the water column oxygen concentration. This variability, which is attributed to the El Niño Southern Oscillation (ENSO), might have implication on the vertical extension of the Eastern Tropical South Pacific (ETSP) oxygen minimum zone. Here using a coupled physical-biogeochemical model, we provide new insights into how ENSO variability affects the vertical extension of the oxygen-poor waters of the ETSP.
Jürgen Fischer, Johannes Karstensen, Marilena Oltmanns, and Sunke Schmidtko
Ocean Sci., 14, 1167–1183, https://doi.org/10.5194/os-14-1167-2018, https://doi.org/10.5194/os-14-1167-2018, 2018
Short summary
Short summary
Based on nearly 17 years of profiling (Argo) float data, high-resolution (~ 25 km grid) maps of mean flow and eddy kinetic energy (EKE) were constructed for the intermediate to deep subpolar North Atlantic. Robust boundary currents along topographic slopes, mid-basin advective pathways, and stagnation regimes were identified. The ratio of mean flow vs. the square root of EKE indicates regions dominated by advection, and large regions in which eddy diffusion prevails.
Rena Czeschel, Florian Schütte, Robert A. Weller, and Lothar Stramma
Ocean Sci., 14, 731–750, https://doi.org/10.5194/os-14-731-2018, https://doi.org/10.5194/os-14-731-2018, 2018
Short summary
Short summary
The mean circulation on the poleward side of the oxygen minimum zone is overlain by eddy activity playing an important role in the distribution of water masses and oxygen within the OMZ. The activity of different types of eddies was investigated during their westward propagation from the formation area off Peru/Chile into the open ocean. The focus was on the development of eddies, seasonal conditions during their formation, and the change of water mass properties transported within the eddies.
Naohiro Kosugi, Daisuke Sasano, Masao Ishii, Shigeto Nishino, Hiroshi Uchida, and Hisayuki Yoshikawa-Inoue
Biogeosciences, 14, 5727–5739, https://doi.org/10.5194/bg-14-5727-2017, https://doi.org/10.5194/bg-14-5727-2017, 2017
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Recent variation in air–sea CO2 flux in the Arctic Ocean is focused. In order to understand the relation between sea ice retreat and CO2 chemistry, we conducted hydrographic observations in the Arctic Ocean in 2013. There were relatively high pCO2 surface layer and low pCO2 subsurface layer in the Canada Basin. The former was due to near-equilibration with the atmosphere and the latter primary production. Both were unlikely mixed by disturbance as large sea-ice melt formed strong stratification.
Johannes Hahn, Peter Brandt, Sunke Schmidtko, and Gerd Krahmann
Ocean Sci., 13, 551–576, https://doi.org/10.5194/os-13-551-2017, https://doi.org/10.5194/os-13-551-2017, 2017
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Recent studies have shown that the eastern tropical North Atlantic is subject to a strong decrease of the oceanic oxygen concentration in the upper 1000 m from the 1960s to today. By analyzing a broad observational data set, this study found an even stronger oxygen decrease in the upper 400 m throughout the past decade, whereas oxygen increase was found below (400–1000 m). Changes in the strength of the zonal currents are the most likely reason for the observed decadal oxygen changes.
Lothar Stramma, Tim Fischer, Damian S. Grundle, Gerd Krahmann, Hermann W. Bange, and Christa A. Marandino
Ocean Sci., 12, 861–873, https://doi.org/10.5194/os-12-861-2016, https://doi.org/10.5194/os-12-861-2016, 2016
Short summary
Short summary
Results from a research cruise on R/V Sonne to the eastern tropical Pacific in October 2015 during the 2015–2016 El Niño show the transition of current, hydrographic, and nutrient conditions to El Niño conditions in the eastern tropical Pacific in October 2015. Although in early 2015 the El Niño was strong and in October 2015 showed a clear El Niño influence on the EUC, in the eastern tropical Pacific the measurements only showed developing El Niño water mass distributions.
Damian L. Arévalo-Martínez, Annette Kock, Carolin R. Löscher, Ruth A. Schmitz, Lothar Stramma, and Hermann W. Bange
Biogeosciences, 13, 1105–1118, https://doi.org/10.5194/bg-13-1105-2016, https://doi.org/10.5194/bg-13-1105-2016, 2016
Short summary
Short summary
We present the first measurements of N2O across three mesoscale eddies in the eastern tropical South Pacific. Eddie's vertical structure, offshore transport, properties during its formation and near-surface primary production determined the N2O distribution. Substantial depletion of N2O within the core of anticyclonic eddies suggests that although these are transient features, N-loss processes within their centres can lead to an enhanced N2O sink which is not accounted for in marine N2O budgets.
L. Stramma, R. Czeschel, T. Tanhua, P. Brandt, M. Visbeck, and B. S. Giese
Ocean Sci., 12, 153–167, https://doi.org/10.5194/os-12-153-2016, https://doi.org/10.5194/os-12-153-2016, 2016
Short summary
Short summary
The subsurface circulation in the eastern tropical North Atlantic OMZ is derived from velocity, float and tracer data and data assimilation results, and shows a cyclonic flow around the Guinea Dome reaching into the oxygen minimum zone. The stronger cyclonic flow around the Guinea Dome in 2009 seem to be connected to a strong Atlantic Meridional Mode (AMM) event.
A continuous deoxygenation trend of the low oxygen layer was confirmed.
Eddy influence is weak south of the Cape Verde Islands.
R. Czeschel, L. Stramma, R. A. Weller, and T. Fischer
Ocean Sci., 11, 455–470, https://doi.org/10.5194/os-11-455-2015, https://doi.org/10.5194/os-11-455-2015, 2015
Short summary
Short summary
Mean circulation in the eastern tropical South Pacific in 50-600m depth is modified by seasonal variability and eddies on the poleward side of the oxygen minimum zone(OMZ). Floats with parking depth at 400m show westward flow in the equatorial channel, sluggish flow in the northern part of the OMZ, and passage of eddies with oxygen anomalies. Net community production rates were estimated from a float. Oxygen decrease in 50-300m depth since 1976 is related to an increase in nitrate and phosphate.
P. Brandt, H. W. Bange, D. Banyte, M. Dengler, S.-H. Didwischus, T. Fischer, R. J. Greatbatch, J. Hahn, T. Kanzow, J. Karstensen, A. Körtzinger, G. Krahmann, S. Schmidtko, L. Stramma, T. Tanhua, and M. Visbeck
Biogeosciences, 12, 489–512, https://doi.org/10.5194/bg-12-489-2015, https://doi.org/10.5194/bg-12-489-2015, 2015
Short summary
Short summary
Our observational study looks at the structure of the eastern tropical North Atlantic (ETNA) oxygen minimum zone (OMZ) in comparison with the less-ventilated, eastern tropical South Pacific OMZ. We quantify the OMZ’s oxygen budget composed of consumption, advection, lateral and vertical mixing. Substantial oxygen variability is observed on interannual to multidecadal timescales. The deoxygenation of the ETNA OMZ during the last decades represents a substantial imbalance of the oxygen budget.
M. Ishii, R. A. Feely, K. B. Rodgers, G.-H. Park, R. Wanninkhof, D. Sasano, H. Sugimoto, C. E. Cosca, S. Nakaoka, M. Telszewski, Y. Nojiri, S. E. Mikaloff Fletcher, Y. Niwa, P. K. Patra, V. Valsala, H. Nakano, I. Lima, S. C. Doney, E. T. Buitenhuis, O. Aumont, J. P. Dunne, A. Lenton, and T. Takahashi
Biogeosciences, 11, 709–734, https://doi.org/10.5194/bg-11-709-2014, https://doi.org/10.5194/bg-11-709-2014, 2014
L. Stramma, H. W. Bange, R. Czeschel, A. Lorenzo, and M. Frank
Biogeosciences, 10, 7293–7306, https://doi.org/10.5194/bg-10-7293-2013, https://doi.org/10.5194/bg-10-7293-2013, 2013
P. J. Llanillo, J. Karstensen, J. L. Pelegrí, and L. Stramma
Biogeosciences, 10, 6339–6355, https://doi.org/10.5194/bg-10-6339-2013, https://doi.org/10.5194/bg-10-6339-2013, 2013
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In this study, we investigate oxygen variability in the deep western boundary current in the Labrador Sea from multiyear moored records. We estimate that about half of the oxygen taken up in the interior Labrador Sea by air–sea gas exchange during deep water formation is exported southward the same year. Our results underline the complexity of the oxygen uptake and export in the Labrador Sea and highlight the important role this region plays in supplying oxygen to the deep ocean.
Céline Ridame, Julie Dinasquet, Søren Hallstrøm, Estelle Bigeard, Lasse Riemann, France Van Wambeke, Matthieu Bressac, Elvira Pulido-Villena, Vincent Taillandier, Fréderic Gazeau, Antonio Tovar-Sanchez, Anne-Claire Baudoux, and Cécile Guieu
Biogeosciences, 19, 415–435, https://doi.org/10.5194/bg-19-415-2022, https://doi.org/10.5194/bg-19-415-2022, 2022
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We show that in the Mediterranean Sea spatial variability in N2 fixation is related to the diazotrophic community composition reflecting different nutrient requirements among species. Nutrient supply by Saharan dust is of great importance to diazotrophs, as shown by the strong stimulation of N2 fixation after a simulated dust event under present and future climate conditions; the magnitude of stimulation depends on the degree of limitation related to the diazotrophic community composition.
Matthew P. Humphreys, Erik H. Meesters, Henk de Haas, Szabina Karancz, Louise Delaigue, Karel Bakker, Gerard Duineveld, Siham de Goeyse, Andreas F. Haas, Furu Mienis, Sharyn Ossebaar, and Fleur C. van Duyl
Biogeosciences, 19, 347–358, https://doi.org/10.5194/bg-19-347-2022, https://doi.org/10.5194/bg-19-347-2022, 2022
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A series of submarine sinkholes were recently discovered on Luymes Bank, part of Saba Bank, a carbonate platform in the Caribbean Netherlands. Here, we investigate the waters inside these sinkholes for the first time. One of the sinkholes contained a body of dense, low-oxygen and low-pH water, which we call the
acid lake. We use measurements of seawater chemistry to work out what processes were responsible for forming the acid lake and discuss the consequences for the carbonate platform.
Gerhard Fischer, Oscar E. Romero, Johannes Karstensen, Karl-Heinz Baumann, Nasrollah Moradi, Morten Iversen, Götz Ruhland, Marco Klann, and Arne Körtzinger
Biogeosciences, 18, 6479–6500, https://doi.org/10.5194/bg-18-6479-2021, https://doi.org/10.5194/bg-18-6479-2021, 2021
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Low-oxygen eddies in the eastern subtropical North Atlantic can form an oasis for phytoplankton growth. Here we report on particle flux dynamics at the oligotrophic Cape Verde Ocean Observatory. We observed consistent flux patterns during the passages of low-oxygen eddies. We found distinct flux peaks in late winter, clearly exceeding background fluxes. Our findings suggest that the low-oxygen eddies sequester higher organic carbon than expected for oligotrophic settings.
Matthieu Bressac, Thibaut Wagener, Nathalie Leblond, Antonio Tovar-Sánchez, Céline Ridame, Vincent Taillandier, Samuel Albani, Sophie Guasco, Aurélie Dufour, Stéphanie H. M. Jacquet, François Dulac, Karine Desboeufs, and Cécile Guieu
Biogeosciences, 18, 6435–6453, https://doi.org/10.5194/bg-18-6435-2021, https://doi.org/10.5194/bg-18-6435-2021, 2021
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Phytoplankton growth is limited by the availability of iron in about 50 % of the ocean. Atmospheric deposition of desert dust represents a key source of iron. Here, we present direct observations of dust deposition in the Mediterranean Sea. A key finding is that the input of iron from dust primarily occurred in the deep ocean, while previous studies mainly focused on the ocean surface. This new insight will enable us to better represent controls on global marine productivity in models.
Léo Berline, Andrea Michelangelo Doglioli, Anne Petrenko, Stéphanie Barrillon, Boris Espinasse, Frederic A. C. Le Moigne, François Simon-Bot, Melilotus Thyssen, and François Carlotti
Biogeosciences, 18, 6377–6392, https://doi.org/10.5194/bg-18-6377-2021, https://doi.org/10.5194/bg-18-6377-2021, 2021
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While the Ionian Sea is considered a nutrient-depleted and low-phytoplankton biomass area, it is a crossroad for water mass circulation. In the central Ionian Sea, we observed a strong contrast in particle distribution across a ~100 km long transect. Using remote sensing and Lagrangian simulations, we suggest that this contrast finds its origin in the long-distance transport of particles from the north, west and east of the Ionian Sea, where phytoplankton production was more intense.
Anna Teruzzi, Giorgio Bolzon, Laura Feudale, and Gianpiero Cossarini
Biogeosciences, 18, 6147–6166, https://doi.org/10.5194/bg-18-6147-2021, https://doi.org/10.5194/bg-18-6147-2021, 2021
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During summer, maxima of phytoplankton chlorophyll concentration (DCM) occur in the subsurface of the Mediterranean Sea and can play a relevant role in carbon sequestration into the ocean interior. A numerical model based on in situ and satellite observations provides insights into the range of DCM conditions across the relatively small Mediterranean Sea and shows a western DCM that is 25 % shallower and with a higher phytoplankton chlorophyll concentration than in the eastern Mediterranean.
Elvira Pulido-Villena, Karine Desboeufs, Kahina Djaoudi, France Van Wambeke, Stéphanie Barrillon, Andrea Doglioli, Anne Petrenko, Vincent Taillandier, Franck Fu, Tiphanie Gaillard, Sophie Guasco, Sandra Nunige, Sylvain Triquet, and Cécile Guieu
Biogeosciences, 18, 5871–5889, https://doi.org/10.5194/bg-18-5871-2021, https://doi.org/10.5194/bg-18-5871-2021, 2021
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We report on phosphorus dynamics in the surface layer of the Mediterranean Sea. Highly sensitive phosphate measurements revealed vertical gradients above the phosphacline. The relative contribution of diapycnal fluxes to total external supply of phosphate to the mixed layer decreased towards the east, where atmospheric deposition dominated. Taken together, external sources of phosphate contributed little to total supply, which was mainly sustained by enzymatic hydrolysis of organic phosphorus.
Zouhair Lachkar, Michael Mehari, Muchamad Al Azhar, Marina Lévy, and Shafer Smith
Biogeosciences, 18, 5831–5849, https://doi.org/10.5194/bg-18-5831-2021, https://doi.org/10.5194/bg-18-5831-2021, 2021
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This study documents and quantifies a significant recent oxygen decline in the upper layers of the Arabian Sea and explores its drivers. Using a modeling approach we show that the fast local warming of sea surface is the main factor causing this oxygen drop. Concomitant summer monsoon intensification contributes to this trend, although to a lesser extent. These changes exacerbate oxygen depletion in the subsurface, threatening marine habitats and altering the local biogeochemistry.
France Van Wambeke, Vincent Taillandier, Karine Desboeufs, Elvira Pulido-Villena, Julie Dinasquet, Anja Engel, Emilio Marañón, Céline Ridame, and Cécile Guieu
Biogeosciences, 18, 5699–5717, https://doi.org/10.5194/bg-18-5699-2021, https://doi.org/10.5194/bg-18-5699-2021, 2021
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Simultaneous in situ measurements of (dry and wet) atmospheric deposition and biogeochemical stocks and fluxes in the sunlit waters of the open Mediterranean Sea revealed complex physical and biological processes occurring within the mixed layer. Nitrogen (N) budgets were computed to compare the sources and sinks of N in the mixed layer. The transitory effect observed after a wet dust deposition impacted the microbial food web down to the deep chlorophyll maximum.
Frédéric Gazeau, France Van Wambeke, Emilio Marañón, Maria Pérez-Lorenzo, Samir Alliouane, Christian Stolpe, Thierry Blasco, Nathalie Leblond, Birthe Zäncker, Anja Engel, Barbara Marie, Julie Dinasquet, and Cécile Guieu
Biogeosciences, 18, 5423–5446, https://doi.org/10.5194/bg-18-5423-2021, https://doi.org/10.5194/bg-18-5423-2021, 2021
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Our study shows that the impact of dust deposition on primary production depends on the initial composition and metabolic state of the tested community and is constrained by the amount of nutrients added, to sustain both the fast response of heterotrophic prokaryotes and the delayed one of phytoplankton. Under future environmental conditions, heterotrophic metabolism will be more impacted than primary production, therefore reducing the capacity of surface waters to sequester anthropogenic CO2.
Loes J. A. Gerringa, Martha Gledhill, Indah Ardiningsih, Niels Muntjewerf, and Luis M. Laglera
Biogeosciences, 18, 5265–5289, https://doi.org/10.5194/bg-18-5265-2021, https://doi.org/10.5194/bg-18-5265-2021, 2021
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For 3 decades, competitive ligand exchange–adsorptive cathodic stripping voltammetry was used to estimate the Fe-binding capacity of organic matter in seawater. In this paper the performance of the competing ligands is compared through the analysis of a series of model ligands.
The main finding of this paper is that the determined speciation parameters are not independent of the application, making interpretation of Fe speciation data more complex than it was thought before.
Frédéric Gazeau, Céline Ridame, France Van Wambeke, Samir Alliouane, Christian Stolpe, Jean-Olivier Irisson, Sophie Marro, Jean-Michel Grisoni, Guillaume De Liège, Sandra Nunige, Kahina Djaoudi, Elvira Pulido-Villena, Julie Dinasquet, Ingrid Obernosterer, Philippe Catala, and Cécile Guieu
Biogeosciences, 18, 5011–5034, https://doi.org/10.5194/bg-18-5011-2021, https://doi.org/10.5194/bg-18-5011-2021, 2021
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This paper shows that the impacts of Saharan dust deposition in different Mediterranean basins are as strong as those observed in coastal waters but differed substantially between the three tested stations, differences attributed to variable initial metabolic states. A stronger impact of warming and acidification on mineralization suggests a decreased capacity of Mediterranean surface communities to sequester CO2 following the deposition of atmospheric particles in the coming decades.
Carolin R. Löscher
Biogeosciences, 18, 4953–4963, https://doi.org/10.5194/bg-18-4953-2021, https://doi.org/10.5194/bg-18-4953-2021, 2021
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The Bay of Bengal (BoB) is classically seen as an ocean region with low primary production, which has been predicted to decrease even further. Here, the importance of such a trend is used to explore what could happen to the BoB's low-oxygen core waters if primary production decreases. Lower biological production leads to less oxygen loss in deeper waters by respiration; thus it could be that oxygen will not further decrease and the BoB will not become anoxic, different to other low-oxygen areas.
Bo Liu, Katharina D. Six, and Tatiana Ilyina
Biogeosciences, 18, 4389–4429, https://doi.org/10.5194/bg-18-4389-2021, https://doi.org/10.5194/bg-18-4389-2021, 2021
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We incorporate a new representation of the stable carbon isotope 13C in a global ocean biogeochemistry model. The model well reproduces the present-day 13C observations. We find a recent observation-based estimate of the oceanic 13C Suess effect (the decrease in 13C/12C ratio due to uptake of anthropogenic CO2; 13CSE) possibly underestimates 13CSE by 0.1–0.26 per mil. The new model will aid in better understanding the past ocean state via comparison to 13C/12C measurements from sediment cores.
Neil J. Wyatt, Angela Milne, Eric P. Achterberg, Thomas J. Browning, Heather A. Bouman, E. Malcolm S. Woodward, and Maeve C. Lohan
Biogeosciences, 18, 4265–4280, https://doi.org/10.5194/bg-18-4265-2021, https://doi.org/10.5194/bg-18-4265-2021, 2021
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Using data collected during two expeditions to the South Atlantic Ocean, we investigated how the interaction between external sources and biological activity influenced the availability of the trace metals zinc and cobalt. This is important as both metals play essential roles in the metabolism and growth of phytoplankton and thus influence primary productivity of the oceans. We found seasonal changes in both processes that helped explain upper-ocean trace metal cycling.
Hannah L. Bourne, James K. B. Bishop, Elizabeth J. Connors, and Todd J. Wood
Biogeosciences, 18, 3053–3086, https://doi.org/10.5194/bg-18-3053-2021, https://doi.org/10.5194/bg-18-3053-2021, 2021
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To learn how the biological carbon pump works in productive coastal upwelling systems, four autonomous carbon flux explorers measured carbon flux through the twilight zone beneath an offshore-flowing filament of biologically productive water. Strikingly different particle classes dominated the carbon fluxes during successive stages of the filament evolution over 30 d. Both flux and transfer efficiency were far greater than expected, suggesting an outsized filament impact in California waters.
Matthieu Roy-Barman, Lorna Foliot, Eric Douville, Nathalie Leblond, Fréderic Gazeau, Matthieu Bressac, Thibaut Wagener, Céline Ridame, Karine Desboeufs, and Cécile Guieu
Biogeosciences, 18, 2663–2678, https://doi.org/10.5194/bg-18-2663-2021, https://doi.org/10.5194/bg-18-2663-2021, 2021
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The release of insoluble elements such as aluminum (Al), iron (Fe), rare earth elements (REEs), thorium (Th) and protactinium (Pa) when Saharan dust falls over the Mediterranean Sea was studied during tank experiments under present and future climate conditions. Each element exhibited different dissolution kinetics and dissolution fractions (always lower than a few percent). Changes in temperature and/or pH under greenhouse conditions lead to a lower Th release and a higher light REE release.
Stéphanie H. M. Jacquet, Dominique Lefèvre, Christian Tamburini, Marc Garel, Frédéric A. C. Le Moigne, Nagib Bhairy, and Sophie Guasco
Biogeosciences, 18, 2205–2212, https://doi.org/10.5194/bg-18-2205-2021, https://doi.org/10.5194/bg-18-2205-2021, 2021
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We present new data concerning the relation between biogenic barium (Baxs, a tracer of carbon remineralization at mesopelagic depths), O2 consumption and prokaryotic heterotrophic production (PHP) in the Mediterranean Sea. The purpose of this paper is to improve our understanding of the relation between Baxs, PHP and O2 and to test the validity of the Dehairs transfer function in the Mediterranean Sea. This relation has never been tested in the Mediterranean Sea.
Natacha Le Grix, Jakob Zscheischler, Charlotte Laufkötter, Cecile S. Rousseaux, and Thomas L. Frölicher
Biogeosciences, 18, 2119–2137, https://doi.org/10.5194/bg-18-2119-2021, https://doi.org/10.5194/bg-18-2119-2021, 2021
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Marine ecosystems could suffer severe damage from the co-occurrence of a marine heat wave with extremely low chlorophyll concentration. Here, we provide a first assessment of compound marine heat wave and
low-chlorophyll events in the global ocean from 1998 to 2018. We reveal hotspots of these compound events in the equatorial Pacific and in the Arabian Sea and show that they mostly occur in summer at high latitudes and their frequency is modulated by large-scale modes of climate variability.
Christopher Holder and Anand Gnanadesikan
Biogeosciences, 18, 1941–1970, https://doi.org/10.5194/bg-18-1941-2021, https://doi.org/10.5194/bg-18-1941-2021, 2021
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A challenge for marine ecologists in studying phytoplankton is linking small-scale relationships found in a lab to broader relationships observed on large scales in the environment. We investigated whether machine learning (ML) could help connect these small- and large-scale relationships. ML was able to provide qualitative information about the small-scale processes from large-scale information. This method could help identify important relationships from observations in future research.
Natasha René van Horsten, Hélène Planquette, Géraldine Sarthou, Thomas James Ryan-Keogh, Thato Nicholas Mtshali, Alakendra Roychoudhury, and Eva Bucciarelli
Biogeosciences Discuss., https://doi.org/10.5194/bg-2021-42, https://doi.org/10.5194/bg-2021-42, 2021
Revised manuscript accepted for BG
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The remineralisation proxy, barite, was measured along 30° E in the Southern Indian Ocean during early austral winter. To our knowledge this is the first reported Southern Ocean winter study. Concentrations throughout the water column were comparable to observations during spring to autumn. By linking satellite primary production to this proxy a possible annual timescale is proposed. These findings also suggest possible inference of carbon remineralisation from satellite data on a basin scale.
Paul J. Tréguer, Jill N. Sutton, Mark Brzezinski, Matthew A. Charette, Timothy Devries, Stephanie Dutkiewicz, Claudia Ehlert, Jon Hawkings, Aude Leynaert, Su Mei Liu, Natalia Llopis Monferrer, María López-Acosta, Manuel Maldonado, Shaily Rahman, Lihua Ran, and Olivier Rouxel
Biogeosciences, 18, 1269–1289, https://doi.org/10.5194/bg-18-1269-2021, https://doi.org/10.5194/bg-18-1269-2021, 2021
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Silicon is the second most abundant element of the Earth's crust. In this review, we show that silicon inputs and outputs, to and from the world ocean, are 57 % and 37 % higher, respectively, than previous estimates. These changes are significant, modifying factors such as the geochemical residence time of silicon, which is now about 8000 years and 2 times faster than previously assumed. We also update the total biogenic silica pelagic production and provide an estimate for sponge production.
Caroline Ulses, Claude Estournel, Marine Fourrier, Laurent Coppola, Fayçal Kessouri, Dominique Lefèvre, and Patrick Marsaleix
Biogeosciences, 18, 937–960, https://doi.org/10.5194/bg-18-937-2021, https://doi.org/10.5194/bg-18-937-2021, 2021
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We analyse the seasonal cycle of O2 and estimate an annual O2 budget in the north-western Mediterranean deep-convection region, using a numerical model. We show that this region acts as a large sink of atmospheric O2 and as a major source of O2 for the western Mediterranean Sea. The decrease in the deep convection intensity predicted in recent projections may have important consequences on the overall uptake of O2 in the Mediterranean Sea and on the O2 exchanges with the Atlantic Ocean.
Fuminori Hashihama, Hiroaki Saito, Taketoshi Kodama, Saori Yasui-Tamura, Jota Kanda, Iwao Tanita, Hiroshi Ogawa, E. Malcolm S. Woodward, Philip W. Boyd, and Ken Furuya
Biogeosciences, 18, 897–915, https://doi.org/10.5194/bg-18-897-2021, https://doi.org/10.5194/bg-18-897-2021, 2021
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We investigated the nutrient assimilation characteristics of deep-water-induced phytoplankton blooms across the subtropical North and South Pacific Ocean. Nutrient drawdown ratios of dissolved inorganic nitrogen to phosphate were anomalously low in the western North Pacific, likely due to the high phosphate uptake capability of low-phosphate-adapted phytoplankton. The anomalous phosphate uptake might influence the maintenance of chronic phosphate depletion in the western North Pacific.
Florian Ricour, Arthur Capet, Fabrizio D'Ortenzio, Bruno Delille, and Marilaure Grégoire
Biogeosciences, 18, 755–774, https://doi.org/10.5194/bg-18-755-2021, https://doi.org/10.5194/bg-18-755-2021, 2021
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This paper addresses the phenology of the deep chlorophyll maximum (DCM) in the Black Sea (BS). We show that the DCM forms in March at a density level set by the winter mixed layer. It maintains this location until June, suggesting an influence of the DCM on light and nutrient profiles rather than mere adaptation to external factors. In summer, the DCM concentrates ~55 % of the chlorophyll in a 10 m layer at ~35 m depth and should be considered a major feature of the BS phytoplankton dynamics.
Robyn E. Tuerena, Joanne Hopkins, Raja S. Ganeshram, Louisa Norman, Camille de la Vega, Rachel Jeffreys, and Claire Mahaffey
Biogeosciences, 18, 637–653, https://doi.org/10.5194/bg-18-637-2021, https://doi.org/10.5194/bg-18-637-2021, 2021
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The Barents Sea is a rapidly changing shallow sea within the Arctic. Here, nitrate, an essential nutrient, is fully consumed by algae in surface waters during summer months. Nitrate is efficiently regenerated in the Barents Sea, and there is no evidence for nitrogen loss from the sediments by denitrification, which is prevalent on other Arctic shelves. This suggests that nitrogen availability in the Barents Sea is largely determined by the supply of nutrients in water masses from the Atlantic.
David Ford
Biogeosciences, 18, 509–534, https://doi.org/10.5194/bg-18-509-2021, https://doi.org/10.5194/bg-18-509-2021, 2021
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Biogeochemical-Argo floats are starting to routinely measure ocean chlorophyll, nutrients, oxygen, and pH. This study generated synthetic observations representing two potential Biogeochemical-Argo observing system designs and created a data assimilation scheme to combine them with an ocean model. The proposed system of 1000 floats brought clear benefits to model results, with additional floats giving further benefit. Existing satellite ocean colour observations gave complementary information.
Mark Hague and Marcello Vichi
Biogeosciences, 18, 25–38, https://doi.org/10.5194/bg-18-25-2021, https://doi.org/10.5194/bg-18-25-2021, 2021
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This paper examines the question of what causes the rapid spring growth of microscopic marine algae (phytoplankton) in the ice-covered ocean surrounding Antarctica. One prominent hypothesis proposes that the melting of sea ice is the primary cause, while our results suggest that this is only part of the explanation. In particular, we show that phytoplankton are able to start growing before the sea ice melts appreciably, much earlier than previously thought.
Arthur Capet, Luc Vandenbulcke, and Marilaure Grégoire
Biogeosciences, 17, 6507–6525, https://doi.org/10.5194/bg-17-6507-2020, https://doi.org/10.5194/bg-17-6507-2020, 2020
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The Black Sea is 2000 m deep, but, due to limited ventilation, only about the upper 100 m contains enough oxygen to support marine life such as fish. This oxygenation depth has been shown to be decreasing (1955–2019). Here, we evidence that atmospheric warming induced a clear shift in an important ventilation mechanism. We highlight the impact of this shift on oxygenation. There are important implications for marine life and carbon and nutrient cycling if this new ventilation regime persists.
Tim Rixen, Greg Cowie, Birgit Gaye, Joaquim Goes, Helga do Rosário Gomes, Raleigh R. Hood, Zouhair Lachkar, Henrike Schmidt, Joachim Segschneider, and Arvind Singh
Biogeosciences, 17, 6051–6080, https://doi.org/10.5194/bg-17-6051-2020, https://doi.org/10.5194/bg-17-6051-2020, 2020
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The northern Indian Ocean hosts an extensive oxygen minimum zone (OMZ), which intensified due to human-induced global changes. This includes the occurrence of anoxic events on the Indian shelf and affects benthic ecosystems and the pelagic ecosystem structure in the Arabian Sea. Consequences for biogeochemical cycles are unknown, which, in addition to the poor representation of mesoscale features, reduces the reliability of predictions of the future OMZ development in the northern Indian Ocean.
Marion Lagarde, Nolwenn Lemaitre, Hélène Planquette, Mélanie Grenier, Moustafa Belhadj, Pascale Lherminier, and Catherine Jeandel
Biogeosciences, 17, 5539–5561, https://doi.org/10.5194/bg-17-5539-2020, https://doi.org/10.5194/bg-17-5539-2020, 2020
Randelle M. Bundy, Alessandro Tagliabue, Nicholas J. Hawco, Peter L. Morton, Benjamin S. Twining, Mariko Hatta, Abigail E. Noble, Mattias R. Cape, Seth G. John, Jay T. Cullen, and Mak A. Saito
Biogeosciences, 17, 4745–4767, https://doi.org/10.5194/bg-17-4745-2020, https://doi.org/10.5194/bg-17-4745-2020, 2020
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Cobalt (Co) is an essential nutrient for ocean microbes and is scarce in most areas of the ocean. This study measured Co concentrations in the Arctic Ocean for the first time and found that Co levels are extremely high in the surface waters of the Canadian Arctic. Although the Co primarily originates from the shelf, the high concentrations persist throughout the central Arctic. Co in the Arctic appears to be increasing over time and might be a source of Co to the North Atlantic.
Friedrich A. Burger, Jasmin G. John, and Thomas L. Frölicher
Biogeosciences, 17, 4633–4662, https://doi.org/10.5194/bg-17-4633-2020, https://doi.org/10.5194/bg-17-4633-2020, 2020
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Ensemble simulations of an Earth system model reveal that ocean acidity extremes have increased in the past few decades and are projected to increase further in terms of frequency, intensity, duration, and volume extent. The increase is not only caused by the long-term ocean acidification due to the uptake of anthropogenic CO2, but also due to changes in short-term variability. The increase in ocean acidity extremes may enhance the risk of detrimental impacts on marine organisms.
Christopher Gordon, Katja Fennel, Clark Richards, Lynn K. Shay, and Jodi K. Brewster
Biogeosciences, 17, 4119–4134, https://doi.org/10.5194/bg-17-4119-2020, https://doi.org/10.5194/bg-17-4119-2020, 2020
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We describe a method for correcting errors in oxygen optode measurements on autonomous platforms in the ocean. The errors result from the relatively slow response time of the sensor. The correction method includes an in situ determination of the effective response time and requires the time stamps of the individual measurements. It is highly relevant for the BGC-Argo program and also applicable to gliders. We also explore if diurnal changes in oxygen can be obtained from profiling floats.
Bin Wang, Katja Fennel, Liuqian Yu, and Christopher Gordon
Biogeosciences, 17, 4059–4074, https://doi.org/10.5194/bg-17-4059-2020, https://doi.org/10.5194/bg-17-4059-2020, 2020
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We assess trade-offs between different types of biological observations, specifically satellite ocean color and BGC-Argo profiles and the benefits of combining both for optimizing a biogeochemical model of the Gulf of Mexico. Using all available observations leads to significant improvements in observed and unobserved variables (including primary production and C export). Our results highlight the significant benefits of BGC-Argo measurements for biogeochemical model optimization and validation.
Bruce L. Greaves, Andrew T. Davidson, Alexander D. Fraser, John P. McKinlay, Andrew Martin, Andrew McMinn, and Simon W. Wright
Biogeosciences, 17, 3815–3835, https://doi.org/10.5194/bg-17-3815-2020, https://doi.org/10.5194/bg-17-3815-2020, 2020
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We observed that variation in the Southern Annular Mode (SAM) over 11 years showed a relationship with the species composition of hard-shelled phytoplankton in the seasonal ice zone (SIZ) of the Southern Ocean. Phytoplankton in the SIZ are productive during the southern spring and summer when the area is ice-free, with production feeding most Antarctic life. The SAM is known to be increasing with climate change, and changes in phytoplankton in the SIZ may have implications for higher life forms.
Vincent Taillandier, Louis Prieur, Fabrizio D'Ortenzio, Maurizio Ribera d'Alcalà, and Elvira Pulido-Villena
Biogeosciences, 17, 3343–3366, https://doi.org/10.5194/bg-17-3343-2020, https://doi.org/10.5194/bg-17-3343-2020, 2020
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This study addresses the role played by vertical diffusion in the nutrient enrichment of the Levantine intermediate waters, a process particularly relevant inside thermohaline staircases. Thanks to a high profiling frequency over a 4-year period, BGC-Argo float observations reveal the temporal continuity of the layering patterns encountered during the cruise PEACETIME and their impact on vertical and lateral transfers of nitrate between the deep reservoir and the surface productive zone.
Coraline Leseurre, Claire Lo Monaco, Gilles Reverdin, Nicolas Metzl, Jonathan Fin, Solveig Olafsdottir, and Virginie Racapé
Biogeosciences, 17, 2553–2577, https://doi.org/10.5194/bg-17-2553-2020, https://doi.org/10.5194/bg-17-2553-2020, 2020
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In this study, we investigate the evolution of CO2 uptake and ocean acidification in the North Atlantic Subpolar surface water. Our results show an important reduction in the capacity of the ocean to absorb CO2 from the atmosphere (1993–2007), due to a rapid increase in the fCO2 and associated with a rapid decrease in pH. Conversely, data obtained during the last decade (2008–2017) show a stagnation of fCO2 (increasing the ocean sink for CO2) and pH.
Cited articles
Amrhein, V., Greenland, S., and McShane, B.: Retire statistical significance,
Nature, 567, 305–307, 2019.
Bange, H. W.: Nutrients measured on water bottle samples during METEOR cruise M91. GEOMAR – Helmholtz Centre for Ocean Research Kiel, PANGAEA, https://doi.org/10.1594/PANGAEA.817174, 2013.
Bange, H. W.: Nutrients measured on water bottle samples during SONNE cruise SO243. PANGAEA, https://doi.org/10.1594/PANGAEA.861391, 2016.
Bograd, S. J., Pozo Buil, M., Di Lorenzo, E., Castro, C. G., Schroeder, I.
D., Goericke, R., Anderson, C. R., Benitez-Nelson, C., and Whitney, F. A.:
Changes in source waters to the Southern California Bight, Deep-Sea Res. Pt. II,
112, 42–52, https://doi.org/10.1016/j.dsr2.2014.04.009, 2015.
Bond, N. A., Cronin, M. F., Freeland, H., and Mantua, N.: Causes and impacts of
the 2014 warm anomaly in the NE Pacific, Geophys. Res. Lett., 42, 3414–3420,
https://doi.org/10.1002/2015GL063306, 2015.
Bretherton, F. P., Davis, R. E., and Fandry, C. B.: A technique for
objective analysis and design of oceanographic experiments applied to
MODE-73, Deep-Sea Res., 23, 559–582,
https://doi.org/10.1016/0011-7471(76)90001-2, 1976.
CCHDO: Welcome to the CCHDO, available at: https://cchdo.ucsd.edu, last access: 13 February 2020.
Calcofi: Calcofi Hydrographic data base, available at: http://www.calcofi.org/ccdata.html, last access: 13 February 2020.
Chavez, F. P., Ryan, J., Lluch-Cota, S. E., and Ňiquen, M.: From
Anchovies to Sardines and back: Multidecdal change in the Pacific Ocean,
Science, 299, 217–221, https://doi.org/10.1126/science.1075880, 2003.
Crawford, W. R. and Peña, M. A.: Decadal trends in oxygen concentration
in subsurface waters of the Northeast Pacific Ocean, Atmos.-Ocean, 54,
171–192, 2016.
Czeschel, R., Stramma, L., Schwarzkopf, F. U., Giese, B. J., Funk, A., and
Karstensen, J.: Middepth circulation of the eastern tropical South Pacific
and its link to the oxygen minimum zone, J. Geophys. Res., 116, C01015,
https://doi.org/10.1029/2010JC006565, 2011.
Czeschel, R., Stramma, L., and Johnson, G. C.: Oxygen decreases and
variability in the eastern equatorial Pacific, J. Geophys. Res., 117,
C11019, https://doi.org/10.1029/2012JC008043, 2012.
Czeschel, R., Stramma, L., Weller, R. A., and Fischer, T.: Circulation, eddies, oxygen, and nutrient changes in the eastern tropical South Pacific Ocean, Ocean Sci., 11, 455–470, https://doi.org/10.5194/os-11-455-2015, 2015.
Deser, C., Alexander, M. A., Xie, S.-P., and Phillips, A. S.: Sea surface
temperature variability: Patterns and mechanisms, Annu. Rev. Mar. Sci., 2,
115–143, https://doi.org/10.1146/annurev-marine-120408-151453, 2010.
Deutsch, C., Brix, H., Ito, T., Frenzel, H., and Thompson, L.:
Climate-forced variability of ocean hypoxia, Science, 333, 336–339,
https://doi.org/10.1126/science.1202422, 2011.
Di Lorenzo, E.: NPGO index monthly averages, available at: http://www.o3d.org/npgo/npgo.php, last access: 13 February 2020.
Di Lorenzo, E. and Mantua, N. J.: Multi-year persistence of the 2014/15 North
Pacific marine heat wave, Nat. Clim. Change, 6, 1042–1047,
https://doi.org/10.1038/nclimate3082, 2016.
Di Lorenzo, E., Schneider, N., Cobb, K. M., Franks, P. J. S., Chhak, K.,
Miller, A. J., McWilliams, J. C., Bograd, S. J., Arango, H., Curchitser, E.,
Powell, T. M., and Riviere, P.: North Pacific Gyre Oscillation links ocean
climate and ecosystem change, Geophys. Res. Lett., 35, L08607,
https://doi.org/10.1029/2007GL032838, 2008.
Di Lorenzo, E., Fiechter, J., Schneider, N., Bracco, A., Miller, A. J.,
Franks, P. J. S., Bograd, S. J., Moore, A. M., Thomas, A. C., Crawford, W.,
Peña, A., and Hermann, A. J.: Nutrient and salinity decadal variations
in the central and eastern North Pacific, Geophys. Res. Lett., 36, L14601,
https://doi.org/10.1029/2009GL038261, 2009.
Duteil, O., Oschlies, A., and Böning, C. W.: Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean, Biogeosciences, 15, 7111–7126, https://doi.org/10.5194/bg-15-7111-2018, 2018.
Frölicher, T. L., Joos, F., Plattner, G.-K., Steinacher, M., and Doney,
S. C.: Natural variability and anthropogenic trends in oceanic oxygen in a
coupled carbon cycle-climate model ensemble, Global Biogeochem. Cy.,
23, GB1003, https://doi.org/10.1029/2008GB003316, 2009.
Graco, M. I., Purca, S., Dewitte, B., Castro, C. G., Morón, O., Ledesma, J., Flores, G., and Gutiérrez, D.: The OMZ and nutrient features as a signature of interannual and low-frequency variability in the Peruvian upwelling system, Biogeosciences, 14, 4601–4617, https://doi.org/10.5194/bg-14-4601-2017, 2017.
Hawaii Ocean time-series: Hawaii Ocean time-series data organization and graphical system, available at: http://hahana.soest.hawaii.edu/hot/hot-dogs/bextraction.html, last access: 13 February 2020.
Hansen, H. P.: Determination of oxygen, in: Methods of Seawater analysis,
edited by: Grasshoff, K., Kremling, K., and Ehrhardt, M., Wiley-VCH,
Weinheim, Germany, 75–89, 1999.
Hansen, H. P. and Koroleff, F.: Determination of nutrients, in: Methods of
Seawater analysis, edited by: Grasshoff, K., Kremling, K., and Ehrhardt, M.,
Wiley-VCH, Weinheim, Germany, 149–158, 1999.
Hansen, J., Ruedy, R., Sato, M., and Lo, K.: Global surface temperature
change, Rev. Geophys., 48, RG4004, https://doi.org/10.1029/2010RG000345,
2010.
IPCC: Climate Change 2013: The Physical Science Basis. Contribution of
Working Group I to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change, edited by: Stocker, T. F., Qin, D., Plattner, G.-K., Tignor,
M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y, Bex, V., and Midgley, P.
M., Cambridge University Press, Cambridge, United Kingdom and New
York, NY, USA, 1535 pp., 2013.
Jackson, J. M., Johnson, G. C., Dosser, H. V., and Ross, T.: Warming from
recent marine heatwave lingers in deep British Columbia Fjord, Geophys. Res.
Lett., 45, 9757–9764, https://doi.org/10.1029/2018GL078971, 2018.
Jacox, M. G., Bograd, S. J., Hazen, E. L., and Fiechter, J.: Sensitivity of
the California Current nutrient supply to wind, heat, and remote ocean
forcing, Geophys. Res. Lett., 42, 5950–5957, https://doi.org/10.1002/2015GL065147,
2015.
Japan Meteororological Society: Oceanographic section time-series dataset for the 137∘E meridian, available at: http://www.data.jma.go.jp/gmd/kaiyou/db/mar_env/results/OI/137E_OI_e.html, last access: 13 February 2020.
Kalvelage, T. Krahmann, G., and Tanhua, T.: Hydrochemistry during METEOR cruise M77/3. IFM-GEOMAR Leibniz-Institute of Marine Sciences, Kiel University, PANGAEA, https://doi.org/10.1594/PANGAEA.793154, 2012.
Kalvelage, T., Lavik, G., Lam, P., Contreras, S., Arteaga, L., Löscher,
C. R., Oschlies, A., Paulmier, A., Stramma, L., and Kuypers, M. M. M.:
Nitrogen cycling driven by organic matter export in the South Pacific oxygen
minimum zone, Nat. Geosci., 6, 228–234,
https://doi.org/10.1038/NGEO1739, 2013.
Karstensen, J., Stramma, L., and Visbeck, M.: Oxygen minimum zones in the
eastern tropical Atlantic and Pacific oceans, Prog. Oceanogr., 77, 331–350,
2008.
Kessler, W.: The circulation of the eastern tropical Pacific: A review,
Prog. Oceanogr., 69, 181–217, 2006.
Kim, I.-N., Lee, K., Gruber, N., Karl, D. M., Bullister, J. L., Yang, S.,
and Kim, T.-W.: Increasing anthropogenic nitrogen in the North Pacific
Ocean, Science, 346, 1102–1106, 2014.
Koslow, J. A., Davison, P., Ferrer, E., Jiménez Rosenberg, S. P. A.,
Aceves-Medina, G., and Watson, W.: The evolving response of mesopelagic
fishes to declining midwater oxygen concentrations in the southern and
central California Current, ICES J. Mar. Sci., 76, 626–638,
https://doi.org/10.1093/icesjms/fsy154, 2019.
Krahmann, G.: Physical oceanography during METEOR cruise M77/4. IFM-GEOMAR Leibniz-Institute of Marine Sciences, Kiel University, PANGAEA, https://doi.org/10.1594/PANGAEA.777907, 2012a.
Krahmann, G.: Physical oceanography during METEOR cruise M77/3. IFM-GEOMAR Leibniz-Institute of Marine Sciences, Kiel University, PANGAEA, https://doi.org/10.1594/PANGAEA.777255, 2012b.
Krahmann, G.: Physical oceanography during METEOR cruise M90. GEOMAR – Helmholtz Centre for Ocean Research Kiel, PANGAEA, https://doi.org/10.1594/PANGAEA.830245, 2014.
Krahmann, G.: Physical oceanography (CTD) during METEOR cruise M138. GEOMAR – Helmholtz Centre for Ocean Research Kiel, PANGAEA, https://doi.org/10.1594/PANGAEA.892575, 2018.
Krahmann, G. and Bange, H. W.: Physical oceanography during METEOR cruise M91. PANGAEA, https://doi.org/10.1594/PANGAEA.858090, 2016.
Mantua, N. J, Hare, S. R., Zhang, Y., Wallace, J. M., and Francis, R. C.: A
Pacific interdecadal climate oscillation with impacts on salmon production,
B. Am. Meteorol. Soc., 78, 1069–1079, 1997.
McPhaden, M. J., Zebiak, S. E., and Glantz, M. H.: ENSO as an Integrating
Concept in Earth Science, Science, 314, 1740–1745,
https://doi.org/10.1126/science.1132588, 2006.
McShane, B. B., Gal, D., Gelman, A., Robert, C., and Tacket, J. L.: Abandon
Statistical Significance, Am. Stat., 73, 235–245, https://doi.org/10.1080/00031305.2018.1527253, 2019.
Meinvielle, M. and Johnson, G. C.: Decadal water-property trends in the
California Undercurrent, with implications for ocean acidification, J.
Geophys. Res.-Oceans, 118, 6687–6703, https://doi.org/10.1002/2013JC009299,
2013.
Miller, A. J., Cayan, D. R., Barnett, T. P., Graham, N. E., and Oberhuber,
J. M.: The 1976–77 climate shift of the Pacific Ocean, Oceanography, 7,
21–26, 1994.
Minobe, S.: Spatio-temporal structure of the pentadecadal variability over
the North Pacific, Prog. Oceanogr., 47, 381–408, 2000.
Nam, S., Takeshita, Y., Frieder, C. A., Martz, T., and Ballard, J.: Seasonal
advection of Pacific Equatorial Water alters oxygen and pH in the Southern
California Bight, J. Geophys. Res.-Oceans, 120, 5387–5399,
https://doi.org/10.1002/2015JC010859, 2015.
NCAR/UCAR: North Pacific (NP) index by Trenberth and Hurrell, monthly and winter, available at: https://climatedataguide.ucar.edu/climate-data/north-pacific-np-index-trenberth-and-hurrell-monthly-and-winter, last access: 13 February 2020.
Ohshima, K. I., Nakanowatari, T., Riser, S., Volkow, Y., and Wakatsuchi, M.:
Freshening and dense shelf water reduction in the Okhotsk Sea linked with
sea ice decline, Prog. Oceanogr., 126, 71–79,
https://doi.org/10.1016/j.pocean.2014.04.020, 2014.
Oka, E., Ishii, M., Nakano, T., Suga, T., Kouketsu, S., Miyamoto, M.,
Nakano, H., Qiu, B., Sugimoto, S., and Takatani, Y.: Fifty yeara of the
137∘ E repeat hydrographic section in the western North Pacific
Ocean, J. Oceanogr., 74, 115–145,
https:/doi.org/10.1007/s10872-017-0461-x, 2018.
Ono, T., Shiomoto, A., and Saino, T.: Recent decrease of summer nutrients
concentrations and future possible shrinkage of the subarctic North Pacific
high-nutrient low-chlorophyll region, Global Biogeochem. Cy., 22,
GB3027, https://doi.org/10.1029/2007GB003092, 2008.
Oschlies, A., Brandt, P., Stramma, L., and Schmidtko, S.: Drivers and
mechanisms of ocean deoxygenation, Nat. Geosci., 11, 467–473,
https://doi.org/10.1038/s41561-018-0152-2, 2018.
Pozo Buil, M. and Di Lorenzo, E.: Decadal dynamics and predictability of
oxygen and subsurface tracers in the California Current, Geophys. Res. Lett.,
44, 4204–4213, https://doi.org/10.1002/2017GL072931, 2017.
Ridder, N. N. and England, M. H.: Sensitivity of ocean oxygenation to
variations in tropical zonal wind stress magnitude, Global Biogeochem.
Cy., 28, 909–926, https://doi.org/10.1002/2013GB004708, 2014.
Royer, T. C.: High-latitude oceanic variability associated with the
18.6-year nodal tide, J. Geophys. Res., 98, 4639–4644,
https://doi.org/10.1029/92JC02750, 1993.
Sasano, D., Takatani, Y., Kosugi, N., Nakano, T., Midorikawa, T., and Ishii,
M.: Multidecadal trends of oxygen and their controlling factors in the
western North Pacific, Global Biogeochem. Cy., 29, 935–956,
https://doi.org/10.1002/2014GB005065, 2015.
Sasano, D., Takatani, Y., Kosugi, N., Nakano, T., Midorikawa, T., and Ishii,
M.: Decline and bidecadal oscillations of dissolved oxygen in the Oyashio
Region and their propagation to the western North Pacific, Global
Biogeochem. Cy., 32, 909–931, https:// doi.org/10.1029/2017GB005876,
2018.
Schmidtko, S., Johnson, G. C., and Lyman, J. M.: MIMOC: A global monthly
isopycnal upper-ocean climatology with mixed layers, J. Geophys. Res.-Oceans, 118, 1658–1672, https://doi.org/10.1002/jgrc.20122, 2013.
Schmidtko, S., Stramma, L., and Visbeck, M.: Decline in global oceanic
oxygen content during the past five decades, Nature, 542, 335–339,
https://doi.org/10.1038/nature21399, 2017.
Schmidtko, S., Visbeck, M., and Krahmann, G.: Physical oceanography (CTD) during METEOR cruise M135. GEOMAR – Helmholtz Centre for Ocean Research Kiel, PANGAEA, https://doi.org/10.1594/PANGAEA.904009, 2019.
Stramma, L. and Krahmann, G.: Physical oceanography during SONNE cruise SO243. PANGAEA, https://doi.org/10.1594/PANGAEA.861388, 2016.
Stramma, L. and Lohmann, M.: Hydrochemistry of water samples during METEOR cruise M90. PANGAEA, https://doi.org/10.1594/PANGAEA.857751, 2016.
Stramma, L., Johnson, G. C., Sprintall, J., and Mohrholz, V.: Expanding
oxygen-minimum zones in the tropical oceans, Science, 320, 655–658,
https://doi.org/10.1126/science.1153847, 2008.
Stramma, L., Schmidtko, S., Levin, L. A., and G. C. Johnson, G. C.: Ocean
oxygen minima expansions and their biological impacts, Deep-Sea Res. Pt.
I, 57, 587–595, 2010.
Stramma, L., Bange, H. W., Czeschel, R., Lorenzo, A., and Frank, M.: On the role of mesoscale eddies for the biological productivity and biogeochemistry in the eastern tropical Pacific Ocean off Peru, Biogeosciences, 10, 7293–7306, https://doi.org/10.5194/bg-10-7293-2013, 2013.
Stramma, L., Fischer, T., Grundle, D. S., Krahmann, G., Bange, H. W., and Marandino, C. A.: Observed El Niño conditions in the eastern tropical Pacific in October 2015, Ocean Sci., 12, 861–873, https://doi.org/10.5194/os-12-861-2016, 2016.
Takatani, Y., Sasano, D., Nakano, T., Midorikawa, T., and Ishii, M.:
Decrease of dissolved oxygen after the mid-1980s in the western North
Pacific subtropical gyre along the 137∘ E repeat section, Global
Biogeochem. Cy., 26, GB2013, https://doi.org/10.1029/2011GB004227, 2012.
Tanhua, T. and Visbeck, M.: Hydrochemistry of water samples during METEOR cruise M135. PANGAEA, https://doi.org/10.1594/PANGAEA.890441, 2018.
Tanhua, T., van Heuven, S., Key, R. M., Velo, A., Olsen, A., and Schirnick, C.: Quality control procedures and methods of the CARINA database, Earth Syst. Sci. Data, 2, 35–49, https://doi.org/10.5194/essd-2-35-2010, 2010.
Tanhua, T., Karstensen, J., Malien, F., Ryabenko, E., and Kock, A.: Hydrochemistry during METEOR cruise M77/4. IFM-GEOMAR Leibniz-Institute of Marine Sciences, Kiel University, PANGAEA, https://doi.org/10.1594/PANGAEA.793153, 2012.
Trenberth, K. E.: Has there been a hiatus?, Science, 349, 691–692,
https://doi.org/10.1126/science.aac9225, 2015.
Ueno, H. and Yasuda, I.: Intermediate water circulation in the North
Pacific subarctic and northern subtropical regions, J. Geophys. Res., 108,
3348, https://doi.org/10.1029/2002JC001372, 2003.
Wang, C. and Fiedler, P. C.: ENSO variability in the eastern tropical
Pacific: A review, Prog. Oceanogr., 69, 239–266, 2006.
Watanabe, Y. W., Wakita, M., Maeda, N., Ono, T., and Gamo T.: Synchronous
bidecadal periodic changes of oxygen, phosphate and temperature between the
Japan Sea deep water and the North Pacific intermediate water, Geophys. Res.
Lett, 30, 2273, https://doi.org/10.1029/2003GL018338, 2003.
Whitney, F. A., Freeland, H. J., and Robert, M.: Persistently declining
oxygen levels in the interior waters of the eastern subarctic Pacific, Prog.
Oceanogr., 75, 179–199, 2007.
Whitney, F. A., Bograd, S. J., and Ono, T.: Nutrient enrichment of the
subarctic Pacific Ocean pycnocline, Geophys. Res. Lett., 40, 2200–2205,
https://doi.org/10.1002/grl.50439, 2013.
Winkler, L. W.: Bestimmung des im Wasser gelösten Sauerstoffs, Ber.
Dtsch. Chem. Ges., 21, 2843–2855, 1888.
Wong, A. P. S., Bindoff, N. L., and Church, J.A.: Freshwater and heat
changes in the North and South Pacific Oceans between 1960s and 1985–94,
J. Climate, 14, 1613–1633, 2001.
Yasuda, I., Osafune, S., and Tatebe, H.: Possible explanation linking
18.6-year period nodal tidal cycle with bi-decadal variations of ocean and
climate in the North Pacific, Geophys. Res. Lett., 33, L08606,
https://doi.org/10.1029/2005GL025237, 2006.
Yasunaka, S., Ono, T., Nojiri, Y., Whitney, F. A., Wada, C., Murata, A.,
Nakaoka, S., and Hosoda, S.: Long-term variability of surface nutrient
concentrations in the North Pacific, Geophys. Res. Lett., 43, 3389–3397,
https://doi.org/10.1002/2016GL068097, 2016.
Short summary
The influence of climate signals in the Pacific, especially the Pacific Decadal Oscillation and the North Pacific Gyre Oscillation, as well as El Niño–La Niña and an 18.6-year nodal tidal cycle on oxygen and nutrient trends is investigated. At different locations in the Pacific Ocean different climate signals dominate. Hence, not only trends related to warming but also the influence of climate signals need to be investigated to understand oxygen and nutrient changes in the ocean.
The influence of climate signals in the Pacific, especially the Pacific Decadal Oscillation and...
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