Articles | Volume 15, issue 9
https://doi.org/10.5194/bg-15-2961-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-15-2961-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
16 May 2018
Research article |
| 16 May 2018
| 16 May 2018
Nutrient availability and the ultimate control of the biological carbon pump in the western tropical South Pacific Ocean
Thierry Moutin
CORRESPONDING AUTHOR
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Thibaut Wagener
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Mathieu Caffin
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Alain Fumenia
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Audrey Gimenez
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Melika Baklouti
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Pascale Bouruet-Aubertot
Sorbonne Universités – UPMC Univ. Paris 06 – LOCEAN, BP100, 4
place Jussieu, 75252 Paris CEDEX 05, France
Mireille Pujo-Pay
Laboratoire d'Océanographie Microbienne – UMR 7321, CNRS –
Sorbonne Universités, UPMC Univ Paris 06, Observatoire
Océanologique, 66650 Banyuls-sur-mer, France
Karine Leblanc
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Dominique Lefevre
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Sandra Helias Nunige
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Nathalie Leblond
Observatoire Océanologique de Villefranche, Laboratoire
d'Océanographie de Villefranche, UMR 7093, Villefranche-sur-mer, France
Olivier Grosso
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
Alain de Verneil
Aix Marseille Univ., CNRS, Université de Toulon, IRD,
OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110,
13288, Marseille, France
The Center for Prototype Climate Modeling, New York University in Abu Dhabi, Abu Dhabi, UAE
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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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Stéphanie H. M. Jacquet, Dominique Lefèvre, Christian Tamburini, Marc Garel, Frédéric A. C. Le Moigne, Nagib Bhairy, and Sophie Guasco
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Caroline Ulses, Claude Estournel, Marine Fourrier, Laurent Coppola, Fayçal Kessouri, Dominique Lefèvre, and Patrick Marsaleix
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Katixa Lajaunie-Salla, Frédéric Diaz, Cathy Wimart-Rousseau, Thibaut Wagener, Dominique Lefèvre, Christophe Yohia, Irène Xueref-Remy, Brian Nathan, Alexandre Armengaud, and Christel Pinazo
Geosci. Model Dev., 14, 295–321, https://doi.org/10.5194/gmd-14-295-2021, https://doi.org/10.5194/gmd-14-295-2021, 2021
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A biogeochemical model of planktonic food webs including a carbonate balance module is applied in the Bay of Marseille (France) to represent the carbon marine cycle expected to change in the future owing to significant increases in anthropogenic emissions of CO2. The model correctly simulates the ranges and seasonal dynamics of most variables of the carbonate system (pH). This study shows that external physical forcings have an important impact on the carbonate equilibrium in this coastal area.
Kahina Djaoudi, France Van Wambeke, Aude Barani, Nagib Bhairy, Servanne Chevaillier, Karine Desboeufs, Sandra Nunige, Mohamed Labiadh, Thierry Henry des Tureaux, Dominique Lefèvre, Amel Nouara, Christos Panagiotopoulos, Marc Tedetti, and Elvira Pulido-Villena
Biogeosciences, 17, 6271–6285, https://doi.org/10.5194/bg-17-6271-2020, https://doi.org/10.5194/bg-17-6271-2020, 2020
Antonio Tovar-Sánchez, Araceli Rodríguez-Romero, Anja Engel, Birthe Zäncker, Franck Fu, Emilio Marañón, María Pérez-Lorenzo, Matthieu Bressac, Thibaut Wagener, Sylvain Triquet, Guillaume Siour, Karine Desboeufs, and Cécile Guieu
Biogeosciences, 17, 2349–2364, https://doi.org/10.5194/bg-17-2349-2020, https://doi.org/10.5194/bg-17-2349-2020, 2020
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Biogeosciences, 16, 1673–1673, https://doi.org/10.5194/bg-16-1673-2019, https://doi.org/10.5194/bg-16-1673-2019, 2019
Christos Panagiotopoulos, Mireille Pujo-Pay, Mar Benavides, France Van Wambeke, and Richard Sempéré
Biogeosciences, 16, 105–116, https://doi.org/10.5194/bg-16-105-2019, https://doi.org/10.5194/bg-16-105-2019, 2019
Pascale Bouruet-Aubertot, Yannis Cuypers, Andrea Doglioli, Mathieu Caffin, Christophe Yohia, Alain de Verneil, Anne Petrenko, Dominique Lefèvre, Hervé Le Goff, Gilles Rougier, Marc Picheral, and Thierry Moutin
Biogeosciences, 15, 7485–7504, https://doi.org/10.5194/bg-15-7485-2018, https://doi.org/10.5194/bg-15-7485-2018, 2018
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The OUTPACE cruise took place between New Caledonia and French Polynesia. The main purpose was to understand how micro-organisms can survive in a very poor environment. One main source of nutrients is at depth, below the euphotic layer where micro-organisms live. The purpose of the turbulence measurements was to determine to which extent turbulence may
upliftnutrients into the euphotic layer. The origin of the turbulence that was found contrasted along the transect was also determined.
François Carlotti, Marc Pagano, Loïc Guilloux, Katty Donoso, Valentina Valdés, Olivier Grosso, and Brian P. V. Hunt
Biogeosciences, 15, 7273–7297, https://doi.org/10.5194/bg-15-7273-2018, https://doi.org/10.5194/bg-15-7273-2018, 2018
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The paper characterizes the zooplankton community and plankton food web processes between New Caledonia and Tahiti (tropical South Pacific) during the austral summer 2015. In this region, the pelagic production depends on N2 fixation by diazotroph microorganisms on which the zooplankton community feeds, supporting a pelagic food chain ending with valuable tuna fisheries. We estimated a contribution of up to 75 % of diazotroph‐derived nitrogen to zooplankton biomass in the Melanesian archipelago.
Audrey Gimenez, Melika Baklouti, Thibaut Wagener, and Thierry Moutin
Biogeosciences, 15, 6573–6589, https://doi.org/10.5194/bg-15-6573-2018, https://doi.org/10.5194/bg-15-6573-2018, 2018
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During the OUTPACE cruise conducted in the oligotrophic to ultra-oligotrophic region of the western tropical South Pacific, two contrasted regions were sampled in terms of N2 fixation rates, primary production rates and nutrient availability. The aim of this work was to investigate the role of N2 fixation in the differences observed between the two contrasted areas by comparing two simulations only differing by the presence or not of N2 fixers using a 1-D biogeochemical–physical coupled model.
Karine Leblanc, Véronique Cornet, Peggy Rimmelin-Maury, Olivier Grosso, Sandra Hélias-Nunige, Camille Brunet, Hervé Claustre, Joséphine Ras, Nathalie Leblond, and Bernard Quéguiner
Biogeosciences, 15, 5595–5620, https://doi.org/10.5194/bg-15-5595-2018, https://doi.org/10.5194/bg-15-5595-2018, 2018
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The Si biogeochemical cycle was studied during two oceanographic cruises in the tropical South Pacific in 2005 and 2015, between New Caledonia and the Chilean upwelling (8–34° S). Some of the lowest levels of biogenic silica stocks were found in the southern Pacific gyre, where Chlorophyll a concentrations are most depleted worldwide. Size-fractionated biogenic silica concentrations as well as Si kinetic uptake experiments revealed biological Si uptake by the picoplanktonic size fraction.
Thibaut Wagener, Nicolas Metzl, Mathieu Caffin, Jonathan Fin, Sandra Helias Nunige, Dominique Lefevre, Claire Lo Monaco, Gilles Rougier, and Thierry Moutin
Biogeosciences, 15, 5221–5236, https://doi.org/10.5194/bg-15-5221-2018, https://doi.org/10.5194/bg-15-5221-2018, 2018
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The western tropical South Pacific was sampled along a longitudinal 4000 km transect (OUTPACE cruise) for the measurement of carbonate parameters (total alkalinity and total inorganic carbon) between the Melanesian Archipelago and the western part of the South Pacific gyre. This paper reports this new dataset and derived properties. We also estimate anthropogenic carbon distribution in the water column using the TrOCA method.
Marine Bretagnon, Aurélien Paulmier, Véronique Garçon, Boris Dewitte, Séréna Illig, Nathalie Leblond, Laurent Coppola, Fernando Campos, Federico Velazco, Christos Panagiotopoulos, Andreas Oschlies, J. Martin Hernandez-Ayon, Helmut Maske, Oscar Vergara, Ivonne Montes, Philippe Martinez, Edgardo Carrasco, Jacques Grelet, Olivier Desprez-De-Gesincourt, Christophe Maes, and Lionel Scouarnec
Biogeosciences, 15, 5093–5111, https://doi.org/10.5194/bg-15-5093-2018, https://doi.org/10.5194/bg-15-5093-2018, 2018
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In oxygen minimum zone, the fate of the organic matter is a key question as the low oxygen condition would preserve the OM and thus enhance the biological carbon pump while the high microbial activity would foster the remineralisation and the greenhouse gases emission. To investigate this paradigm, sediment traps were deployed off Peru. We pointed out the influence of the oxygenation as well as the organic matter quantity and quality on the carbon transfer efficiency in the oxygen minimum zone.
Sophie Bonnet, Mathieu Caffin, Hugo Berthelot, Olivier Grosso, Mar Benavides, Sandra Helias-Nunige, Cécile Guieu, Marcus Stenegren, and Rachel Ann Foster
Biogeosciences, 15, 4215–4232, https://doi.org/10.5194/bg-15-4215-2018, https://doi.org/10.5194/bg-15-4215-2018, 2018
Dina Spungin, Natalia Belkin, Rachel A. Foster, Marcus Stenegren, Andrea Caputo, Mireille Pujo-Pay, Nathalie Leblond, Cécile Dupouy, Sophie Bonnet, and Ilana Berman-Frank
Biogeosciences, 15, 3893–3908, https://doi.org/10.5194/bg-15-3893-2018, https://doi.org/10.5194/bg-15-3893-2018, 2018
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The way marine organisms die can determine the fate of organic matter (OM) in the ocean. We investigated whether a form of auto-induced programmed cell death (PCD) influenced phytoplankton mortality and fate of OM. Our results from high biomass blooms of the cyanobacterium Trichodesmium show evidence for PCD and high production of sticky carbon material termed transparent exopolymeric particles (TEP) that facilitates cellular aggregation and enhances the vertical flux of OM to depth.
Mathieu Caffin, Hugo Berthelot, Véronique Cornet-Barthaux, Aude Barani, and Sophie Bonnet
Biogeosciences, 15, 3795–3810, https://doi.org/10.5194/bg-15-3795-2018, https://doi.org/10.5194/bg-15-3795-2018, 2018
Mar Benavides, Katyanne M. Shoemaker, Pia H. Moisander, Jutta Niggemann, Thorsten Dittmar, Solange Duhamel, Olivier Grosso, Mireille Pujo-Pay, Sandra Hélias-Nunige, Alain Fumenia, and Sophie Bonnet
Biogeosciences, 15, 3107–3119, https://doi.org/10.5194/bg-15-3107-2018, https://doi.org/10.5194/bg-15-3107-2018, 2018
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We measured N2 fixation rates and identified diazotrophic phylotypes in the mesopelagic layer along a transect spanning from New Caledonia to French Polynesia. N2 fixation rates were low but consistently detected across all depths and stations. A distinct diazotrophic phylotype dominated at 650 dbar, coinciding with the oxygenated Subantarctic Mode Water (SAMW) and suggesting that the distribution of aphotic diazotroph communities is to some extent controlled by water mass structure.
France Van Wambeke, Audrey Gimenez, Solange Duhamel, Cécile Dupouy, Dominique Lefevre, Mireille Pujo-Pay, and Thierry Moutin
Biogeosciences, 15, 2669–2689, https://doi.org/10.5194/bg-15-2669-2018, https://doi.org/10.5194/bg-15-2669-2018, 2018
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The western tropical South Pacific Ocean has recently been shown to be a hotspot for biological nitrogen fixation. In this study, we examined the horizontal and vertical distribution of heterotrophic prokaryotic production alongside photosynthetic rates, nitrogen fixation rates and phosphate turnover times across the western tropical South Pacific Ocean, in order to relate these fluxes to bottom–up controls (related to nitrogen, phosphate and labile C availability).
Angela N. Knapp, Kelly M. McCabe, Olivier Grosso, Nathalie Leblond, Thierry Moutin, and Sophie Bonnet
Biogeosciences, 15, 2619–2628, https://doi.org/10.5194/bg-15-2619-2018, https://doi.org/10.5194/bg-15-2619-2018, 2018
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The spatial distribution of biological N2 fixation fluxes to the ocean remains poorly constrained. Here we use nitrogen isotope budgets to identify significant N2 fixation inputs to the western tropical South Pacific (WTSP), where N2 fixation supports > 50 % of export production at stations proximal to iron sources. The significant N2 fixation inputs in the WTSP may offset nitrogen loss in the oxygen-deficient zones of the eastern tropical South Pacific.
Mathieu Caffin, Thierry Moutin, Rachel Ann Foster, Pascale Bouruet-Aubertot, Andrea Michelangelo Doglioli, Hugo Berthelot, Cécile Guieu, Olivier Grosso, Sandra Helias-Nunige, Nathalie Leblond, Audrey Gimenez, Anne Alexandra Petrenko, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 15, 2565–2585, https://doi.org/10.5194/bg-15-2565-2018, https://doi.org/10.5194/bg-15-2565-2018, 2018
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We performed N budgets to assess the role of N2 fixation on production and export in the western tropical South Pacific Ocean. We deployed a combination of techniques including high-sensitivity measurements of N input and sediment traps deployment. We demonstrated that N2 fixation was the major source of new N before atmospheric deposition and upward nitrate fluxes. It contributed significantly to organic matter export, indicating a high efficiency of this region to export carbon.
Louise Rousselet, Alain de Verneil, Andrea M. Doglioli, Anne A. Petrenko, Solange Duhamel, Christophe Maes, and Bruno Blanke
Biogeosciences, 15, 2411–2431, https://doi.org/10.5194/bg-15-2411-2018, https://doi.org/10.5194/bg-15-2411-2018, 2018
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The patterns of the large- and fine-scale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE oceanographic cruise. The combined use of in situ and satellite data allows for the identification of water mass transport pathways and fine-scale structures, such as fronts, that drive surface distribution of tracers and microbial community structures.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, Christophe Maes, Pascale Bouruet-Aubertot, and Thierry Moutin
Biogeosciences, 15, 2125–2147, https://doi.org/10.5194/bg-15-2125-2018, https://doi.org/10.5194/bg-15-2125-2018, 2018
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Oceanographic campaigns to measure biogeochemical processes popularly deploy drifters with onboard incubations to stay in a single body of water. Here, we aggregate physical data taken during such a cruise, OUTPACE, to independently test in a new approach whether the drifter really stayed in what can be considered a single biological or chemical environment. This study concludes that future campaigns would benefit from similar data collection and analysis to validate their sampling strategy.
Vincent Taillandier, Thibaut Wagener, Fabrizio D'Ortenzio, Nicolas Mayot, Hervé Legoff, Joséphine Ras, Laurent Coppola, Orens Pasqueron de Fommervault, Catherine Schmechtig, Emilie Diamond, Henry Bittig, Dominique Lefevre, Edouard Leymarie, Antoine Poteau, and Louis Prieur
Earth Syst. Sci. Data, 10, 627–641, https://doi.org/10.5194/essd-10-627-2018, https://doi.org/10.5194/essd-10-627-2018, 2018
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We report on data from an oceanographic cruise, covering western, central and eastern parts of the Mediterranean Sea. This cruise was fully dedicated to the maintenance and the metrological verification of a biogeochemical observing system based on a fleet of BGC-Argo floats.
Pierre Marrec, Gérald Grégori, Andrea M. Doglioli, Mathilde Dugenne, Alice Della Penna, Nagib Bhairy, Thierry Cariou, Sandra Hélias Nunige, Soumaya Lahbib, Gilles Rougier, Thibaut Wagener, and Melilotus Thyssen
Biogeosciences, 15, 1579–1606, https://doi.org/10.5194/bg-15-1579-2018, https://doi.org/10.5194/bg-15-1579-2018, 2018
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The objective of this study was to better understand the variability of the phytoplankton community structure in small physical structures at the surface of the ocean. After identifying such a structure in the Mediterranean Sea, we deployed cutting-edge physical and biological sensors in order to observe at a high frequency the dynamics of this structure. From these observations we described the variations of the phytoplankton community structure and how the physics controls this variability.
Alain Fumenia, Thierry Moutin, Sophie Bonnet, Mar Benavides, Anne Petrenko, Sandra Helias Nunige, and Christophe Maes
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-557, https://doi.org/10.5194/bg-2017-557, 2018
Revised manuscript not accepted
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The Melanesian archipelago waters between 160° E and 170° W are characterized by a significant N2 fixation rates and an excess of particulate organic nitrogen compared to the canonical ratio of Redfield and a positive N*. We hypothesize that the southern branch of the subtropical gyre is probably the main vector of excess nitrogen transport in the thermocline waters showing an influence of nitrogen fixation occurring in the western tropical in a large part of the South Pacific.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, and Thierry Moutin
Biogeosciences, 14, 3471–3486, https://doi.org/10.5194/bg-14-3471-2017, https://doi.org/10.5194/bg-14-3471-2017, 2017
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A surface summer plankton bloom in the western tropical South Pacific was sampled during the Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) cruise. We characterize the bloom's properties and the circulation responsible for its evolution. Nitrogen fixation helped sustain the bloom, and larger-scale flows, rather than the smaller ones, explain its movements. Future studies of blooms in this region can make use of these findings to track the horizontal export of plankton production.
Thierry Moutin, Andrea Michelangelo Doglioli, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 14, 3207–3220, https://doi.org/10.5194/bg-14-3207-2017, https://doi.org/10.5194/bg-14-3207-2017, 2017
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The overall goal of OUTPACE was to obtain a successful representation of the interactions between planktonic organisms and the cycle of biogenic elements in the western tropical South Pacific Ocean across trophic and N2 fixation gradients. The international OUTPACE cruise took place between 18 February and 3 April 2015 aboard the RV L’Atalante and involved 60 scientists. The transect covered ~4 000 km from the western part of the Melanesian archipelago to the western boundary of the gyre.
Audrey Gimenez, Melika Baklouti, Sophie Bonnet, and Thierry Moutin
Biogeosciences, 13, 5103–5120, https://doi.org/10.5194/bg-13-5103-2016, https://doi.org/10.5194/bg-13-5103-2016, 2016
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In the context of the VAHINE mesocosm experiment in the Nouméa lagoon (New Caledonia), a 1-D vertical biogeochemical mechanistic model was used together with the in situ experiment to complement our comprehension of the planktonic ecosystem dynamics and the main biogeochemical carbon, nitrogen and phosphate fluxes. The model also showed the fate of fixed N2 by providing, over time, the proportion of diazotroph-derived nitrogen (DDN) in each compartment (mineral and organic) of the model.
Angela N. Knapp, Sarah E. Fawcett, Alfredo Martínez-Garcia, Nathalie Leblond, Thierry Moutin, and Sophie Bonnet
Biogeosciences, 13, 4645–4657, https://doi.org/10.5194/bg-13-4645-2016, https://doi.org/10.5194/bg-13-4645-2016, 2016
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The goal of this manuscript was to track the fate of newly fixed nitrogen (N) in large volume mesocosms in the coastal waters of New Caledonia. We used a N isotope ("δ15N") budget and found a shift in the δ15N of sinking particulate N over the 23-day experiment, indicating that nitrate supported export production at the beginning of the experiment, but that nitrogen fixation supported export at the end. We infer that nitrogen fixation supported export production by a release of dissolved N.
Ilana Berman-Frank, Dina Spungin, Eyal Rahav, France Van Wambeke, Kendra Turk-Kubo, and Thierry Moutin
Biogeosciences, 13, 3793–3805, https://doi.org/10.5194/bg-13-3793-2016, https://doi.org/10.5194/bg-13-3793-2016, 2016
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In the marine environment, sticky sugar-containing gels, termed transparent exopolymeric particles (TEP), are produced from biological sources and physical and chemical processes. These compounds are essential vectors enhancing downward flow of organic matter and its storage at depth. Spatial and temporal dynamics of TEPs were followed for 23 days during the VAHINE mesocosm experiment that investigated the fate of nitrogen and carbon derived from organisms fixing atmospheric N2 (diazotrophs).
France Van Wambeke, Ulrike Pfreundt, Aude Barani, Hugo Berthelot, Thierry Moutin, Martine Rodier, Wolfgang R. Hess, and Sophie Bonnet
Biogeosciences, 13, 3187–3202, https://doi.org/10.5194/bg-13-3187-2016, https://doi.org/10.5194/bg-13-3187-2016, 2016
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The phytoplankton is at the base of the plankton food web in large parts of oceanic "deserts" such as the South Pacific Ocean, where nitrogen sources limit activity. Mesocosms were fertilized with phosphorus to stimulate diazotrophy (atmospheric N2 fixation). Mostly diazotroph-derived nitrogen fuelled the heterotrophic bacterial community through indirect processes generating dissolved organic matter and detritus, such as mortality, lysis and grazing of both diazotrophs and non-diazotrophs.
Sophie Bonnet, Thierry Moutin, Martine Rodier, Jean-Michel Grisoni, Francis Louis, Eric Folcher, Bertrand Bourgeois, Jean-Michel Boré, and Armelle Renaud
Biogeosciences, 13, 2803–2814, https://doi.org/10.5194/bg-13-2803-2016, https://doi.org/10.5194/bg-13-2803-2016, 2016
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e main goal of the VAHINE project was to study the fate of N2 fixation in the ocean. Three large-volume (~ 50 m3) mesocosms were deployed in a tropical oligotrophic ecosystem (the New Caledonia lagoon, south-eastern Pacific). This introductory paper describes the scientific objectives of the project in detail as well as the implementation plan: the mesocosm description and deployment, the selection of the study site, and the logistical and sampling strategy.
A. Guyennon, M. Baklouti, F. Diaz, J. Palmieri, J. Beuvier, C. Lebaupin-Brossier, T. Arsouze, K. Béranger, J.-C. Dutay, and T. Moutin
Biogeosciences, 12, 7025–7046, https://doi.org/10.5194/bg-12-7025-2015, https://doi.org/10.5194/bg-12-7025-2015, 2015
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Dissolved organic carbon (DOC) has already been identified as a potentially significant source of carbon export in the Mediterranean Sea, though in situ export estimations are scarce. This work provides a thorough analysis at basin scale of carbon export with the coupled model NEMO-MED12/Eco3M-MED model. The seasonality and the processes of particulate and dissolved carbon production are also investigated. DOC export appears to be dominant in most regions, especially in the eastern basin.
H. Berthelot, T. Moutin, S. L'Helguen, K. Leblanc, S. Hélias, O. Grosso, N. Leblond, B. Charrière, and S. Bonnet
Biogeosciences, 12, 4099–4112, https://doi.org/10.5194/bg-12-4099-2015, https://doi.org/10.5194/bg-12-4099-2015, 2015
A. Talarmin, F. Van Wambeke, P. Lebaron, and T. Moutin
Biogeosciences, 12, 1237–1247, https://doi.org/10.5194/bg-12-1237-2015, https://doi.org/10.5194/bg-12-1237-2015, 2015
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Along a transect in the warm nutrient-depleted Mediterranean Sea, we found that microorganisms shared phosphate resources by using different uptake strategies. Heterotrophic prokaryotes dominated phosphate uptake in the upper layers while cyanobacteria dominated uptake fluxes around the deep chlorophyll maximum depth. Synechococcus seemed well equipped to respond to pulses of phosphate, whereas Prochlorococcus and heterotrophs were more adapted to very low concentrations.
U. Christaki, D. Lefèvre, C. Georges, J. Colombet, P. Catala, C. Courties, T. Sime-Ngando, S. Blain, and I. Obernosterer
Biogeosciences, 11, 6739–6753, https://doi.org/10.5194/bg-11-6739-2014, https://doi.org/10.5194/bg-11-6739-2014, 2014
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The concurrent investigation of several parameters has provided insight into two key roles of heterotrophic bacteria, and the microbial food web functioning, at the onset and late phase of the spring phytoplankton bloom induced by natural iron fertilization in the Southern Ocean.
K. Desboeufs, N. Leblond, T. Wagener, E. Bon Nguyen, and C. Guieu
Biogeosciences, 11, 5581–5594, https://doi.org/10.5194/bg-11-5581-2014, https://doi.org/10.5194/bg-11-5581-2014, 2014
Related subject area
Biogeochemistry: Open Ocean
Reviews and syntheses: expanding the global coverage of gross primary production and net community production measurements using Biogeochemical-Argo floats
Characteristics of surface physical and biogeochemical parameters within mesoscale eddies in the Southern Ocean
Seasonal dynamics and annual budget of dissolved inorganic carbon in the northwestern Mediterranean deep-convection region
The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes
Reconstructing the ocean's mesopelagic zone carbon budget: sensitivity and estimation of parameters associated with prokaryotic remineralization
Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: a stable isotope approach
Linking northeastern North Pacific oxygen changes to upstream surface outcrop variations
Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone
Optimal parameters for the ocean's nutrient, carbon, and oxygen cycles compensate for circulation biases but replumb the biological pump
Importance of multiple sources of iron for the upper-ocean biogeochemistry over the northern Indian Ocean
Exploring the role of different data types and timescales in the quality of marine biogeochemical model calibration
All about nitrite: exploring nitrite sources and sinks in the eastern tropical North Pacific oxygen minimum zone
Technical note: Enhancement of float-pH data quality control methods: A study case in the Subpolar Northwestern Atlantic region
Fossil coccolith morphological attributes as a new proxy for deep ocean carbonate chemistry
Underestimation of global O2 loss in optimally interpolated historical ocean observations
Reconstructing ocean carbon storage with CMIP6 Earth system models and synthetic Argo observations
Testing the influence of light on nitrite cycling rates in eastern tropical North Pacific
Using machine learning and Biogeochemical-Argo (BGC-Argo) floats to assess biogeochemical models and optimize observing system design
The representation of alkalinity and the carbonate pump from CMIP5 to CMIP6 Earth system models and implications for the carbon cycle
North Atlantic patterns of primary production and phenology in two Earth System Models
Model estimates of metazoans' contributions to the biological carbon pump
Tracing differences in iron supply to the Mid-Atlantic Ridge valley between hydrothermal vent sites: implications for the addition of iron to the deep ocean
Nitrite cycling in the primary nitrite maxima of the eastern tropical North Pacific
Hotspots and drivers of compound marine heatwaves and low net primary production extremes
Ecosystem impacts of marine heat waves in the northeast Pacific
Tracing the role of Arctic shelf processes in Si and N cycling and export through the Fram Strait: insights from combined silicon and nitrate isotopes
Controls on the relative abundances and rates of nitrifying microorganisms in the ocean
The response of diazotrophs to nutrient amendment in the South China Sea and western North Pacific
Influence of GEOTRACES data distribution and misfit function choice on objective parameter retrieval in a marine zinc cycle model
Physiological flexibility of phytoplankton impacts modelled chlorophyll and primary production across the North Pacific Ocean
Observation-constrained estimates of the global ocean carbon sink from Earth system models
Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise)
Controlling factors on the global distribution of a representative marine non-cyanobacterial diazotroph phylotype (Gamma A)
Summer trends and drivers of sea surface fCO2 and pH changes observed in the southern Indian Ocean over the last two decades (1998–2019)
Global nutrient cycling by commercially targeted marine fish
Major processes of the dissolved cobalt cycle in the North and equatorial Pacific Ocean
The impact of the South-East Madagascar Bloom on the oceanic CO2 sink
Nitrite regeneration in the oligotrophic Atlantic Ocean
Bridging the gaps between particulate backscattering measurements and modeled particulate organic carbon in the ocean
Biological production in two contrasted regions of the Mediterranean Sea during the oligotrophic period: an estimate based on the diel cycle of optical properties measured by BioGeoChemical-Argo profiling floats
Acidification of the Nordic Seas
Reconstruction of global surface ocean pCO2 using region-specific predictors based on a stepwise FFNN regression algorithm
Biogeochemical controls on ammonium accumulation in the surface layer of the Southern Ocean
Oxygen export to the deep ocean following Labrador Sea Water formation
N2 fixation in the Mediterranean Sea related to the composition of the diazotrophic community and impact of dust under present and future environmental conditions
Dissolution of a submarine carbonate platform by a submerged lake of acidic seawater
Seasonal flux patterns and carbon transport from low-oxygen eddies at the Cape Verde Ocean Observatory: lessons learned from a time series sediment trap study (2009–2016)
Subsurface iron accumulation and rapid aluminum removal in the Mediterranean following African dust deposition
Long-distance particle transport to the central Ionian Sea
Deep chlorophyll maximum and nutricline in the Mediterranean Sea: emerging properties from a multi-platform assimilated biogeochemical model experiment
Robert W. Izett, Katja Fennel, Adam C. Stoer, and David P. Nicholson
Biogeosciences, 21, 13–47, https://doi.org/10.5194/bg-21-13-2024, https://doi.org/10.5194/bg-21-13-2024, 2024
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This paper provides an overview of the capacity to expand the global coverage of marine primary production estimates using autonomous ocean-going instruments, called Biogeochemical-Argo floats. We review existing approaches to quantifying primary production using floats, provide examples of the current implementation of the methods, and offer insights into how they can be better exploited. This paper is timely, given the ongoing expansion of the Biogeochemical-Argo array.
Qian Liu, Yingjie Liu, and Xiaofeng Li
Biogeosciences, 20, 4857–4874, https://doi.org/10.5194/bg-20-4857-2023, https://doi.org/10.5194/bg-20-4857-2023, 2023
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In the Southern Ocean, abundant eddies behave opposite to our expectations. That is, anticyclonic (cyclonic) eddies are cold (warm). By investigating the variations of physical and biochemical parameters in eddies, we find that abnormal eddies have unique and significant effects on modulating the parameters. This study fills a gap in understanding the effects of abnormal eddies on physical and biochemical parameters in the Southern Ocean.
Caroline Ulses, Claude Estournel, Patrick Marsaleix, Karline Soetaert, Marine Fourrier, Laurent Coppola, Dominique Lefèvre, Franck Touratier, Catherine Goyet, Véronique Guglielmi, Fayçal Kessouri, Pierre Testor, and Xavier Durrieu de Madron
Biogeosciences, 20, 4683–4710, https://doi.org/10.5194/bg-20-4683-2023, https://doi.org/10.5194/bg-20-4683-2023, 2023
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Deep convection plays a key role in the circulation, thermodynamics, and biogeochemical cycles in the Mediterranean Sea, considered to be a hotspot of biodiversity and climate change. In this study, we investigate the seasonal and annual budget of dissolved inorganic carbon in the deep-convection area of the northwestern Mediterranean Sea.
Daniela König and Alessandro Tagliabue
Biogeosciences, 20, 4197–4212, https://doi.org/10.5194/bg-20-4197-2023, https://doi.org/10.5194/bg-20-4197-2023, 2023
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Using model simulations, we show that natural and anthropogenic changes in the global climate leave a distinct fingerprint in the isotopic signatures of iron in the surface ocean. We find that these climate effects on iron isotopes are often caused by the redistribution of iron from different external sources to the ocean, due to changes in ocean currents, and by changes in algal growth, which take up iron. Thus, isotopes may help detect climate-induced changes in iron supply and algal uptake.
Chloé Baumas, Robin Fuchs, Marc Garel, Jean-Christophe Poggiale, Laurent Memery, Frédéric A. C. Le Moigne, and Christian Tamburini
Biogeosciences, 20, 4165–4182, https://doi.org/10.5194/bg-20-4165-2023, https://doi.org/10.5194/bg-20-4165-2023, 2023
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Through the sink of particles in the ocean, carbon (C) is exported and sequestered when reaching 1000 m. Attempts to quantify C exported vs. C consumed by heterotrophs have increased. Yet most of the conducted estimations have led to C demands several times higher than C export. The choice of parameters greatly impacts the results. As theses parameters are overlooked, non-accurate values are often used. In this study we show that C budgets can be well balanced when using appropriate values.
Anna Belcher, Sian F. Henley, Katharine Hendry, Marianne Wootton, Lisa Friberg, Ursula Dallman, Tong Wang, Christopher Coath, and Clara Manno
Biogeosciences, 20, 3573–3591, https://doi.org/10.5194/bg-20-3573-2023, https://doi.org/10.5194/bg-20-3573-2023, 2023
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The oceans play a crucial role in the uptake of atmospheric carbon dioxide, particularly the Southern Ocean. The biological pumping of carbon from the surface to the deep ocean is key to this. Using sediment trap samples from the Scotia Sea, we examine biogeochemical fluxes of carbon, nitrogen, and biogenic silica and their stable isotope compositions. We find phytoplankton community structure and physically mediated processes are important controls on particulate fluxes to the deep ocean.
Sabine Mecking and Kyla Drushka
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-132, https://doi.org/10.5194/bg-2023-132, 2023
Revised manuscript accepted for BG
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This study investigates whether northeastern North Pacific oxygen changes may be caused by surface density changes in the northwest as water moves along density horizons from the surface into the subsurface ocean. A correlation is found with a lag that matches about the travel time of water from the northwest to the northeast. Salinity is the main driver causing decadal changes in surface density whereas salinity and temperature contribute about equally to long-term declining density trends.
Asmita Singh, Susanne Fietz, Sandy J. Thomalla, Nicolas Sanchez, Murat V. Ardelan, Sébastien Moreau, Hanna M. Kauko, Agneta Fransson, Melissa Chierici, Saumik Samanta, Thato N. Mtshali, Alakendra N. Roychoudhury, and Thomas J. Ryan-Keogh
Biogeosciences, 20, 3073–3091, https://doi.org/10.5194/bg-20-3073-2023, https://doi.org/10.5194/bg-20-3073-2023, 2023
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Despite the scarcity of iron in the Southern Ocean, seasonal blooms occur due to changes in nutrient and light availability. Surprisingly, during an autumn bloom in the Antarctic sea-ice zone, the results from incubation experiments showed no significant photophysiological response of phytoplankton to iron addition. This suggests that ambient iron concentrations were sufficient, challenging the notion of iron deficiency in the Southern Ocean through extended iron-replete post-bloom conditions.
Benoît Pasquier, Mark Holzer, Matthew A. Chamberlain, Richard J. Matear, Nathaniel L. Bindoff, and François W. Primeau
Biogeosciences, 20, 2985–3009, https://doi.org/10.5194/bg-20-2985-2023, https://doi.org/10.5194/bg-20-2985-2023, 2023
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Modeling the ocean's carbon and oxygen cycles accurately is challenging. Parameter optimization improves the fit to observed tracers but can introduce artifacts in the biological pump. Organic-matter production and subsurface remineralization rates adjust to compensate for circulation biases, changing the pathways and timescales with which nutrients return to the surface. Circulation biases can thus strongly alter the system’s response to ecological change, even when parameters are optimized.
Priyanka Banerjee
Biogeosciences, 20, 2613–2643, https://doi.org/10.5194/bg-20-2613-2023, https://doi.org/10.5194/bg-20-2613-2023, 2023
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This study shows that atmospheric deposition is the most important source of iron to the upper northern Indian Ocean for phytoplankton growth. This is followed by iron from continental-shelf sediment. Phytoplankton increase following iron addition is possible only with high background levels of nitrate. Vertical mixing is the most important physical process supplying iron to the upper ocean in this region throughout the year. The importance of ocean currents in supplying iron varies seasonally.
Iris Kriest, Julia Getzlaff, Angela Landolfi, Volkmar Sauerland, Markus Schartau, and Andreas Oschlies
Biogeosciences, 20, 2645–2669, https://doi.org/10.5194/bg-20-2645-2023, https://doi.org/10.5194/bg-20-2645-2023, 2023
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Global biogeochemical ocean models are often subjectively assessed and tuned against observations. We applied different strategies to calibrate a global model against observations. Although the calibrated models show similar tracer distributions at the surface, they differ in global biogeochemical fluxes, especially in global particle flux. Simulated global volume of oxygen minimum zones varies strongly with calibration strategy and over time, rendering its temporal extrapolation difficult.
John C. Tracey, Andrew R. Babbin, Elizabeth Wallace, Xin Sun, Katherine L. DuRussel, Claudia Frey, Donald E. Martocello III, Tyler Tamasi, Sergey Oleynik, and Bess B. Ward
Biogeosciences, 20, 2499–2523, https://doi.org/10.5194/bg-20-2499-2023, https://doi.org/10.5194/bg-20-2499-2023, 2023
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Nitrogen (N) is essential for life; thus, its availability plays a key role in determining marine productivity. Using incubations of seawater spiked with a rare form of N measurable on a mass spectrometer, we quantified microbial pathways that determine marine N availability. The results show that pathways that recycle N have higher rates than those that result in its loss from biomass and present new evidence for anaerobic nitrite oxidation, a process long thought to be strictly aerobic.
Cathy Wimart-Rousseau, Tobias Steinhoff, Birgit Klein, Henry Bittig, and Arne Körtzinger
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-76, https://doi.org/10.5194/bg-2023-76, 2023
Revised manuscript accepted for BG
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The marine CO2 system can be measured independently and continuously by BGC-Argo floats since numerous pH sensors have been developed to suit on these autonomous measurements platforms. By applying the Argo correction routines to float-pH data acquired in the subpolar North Atlantic Ocean, we report the uncertainty and lack of objective criteria associated with the choice of the reference method as well the reference depth for the pH correction.
Amanda Gerotto, Hongrui Zhang, Renata Hanae Nagai, Heather M. Stoll, Rubens César Lopes Figueira, Chuanlian Liu, and Iván Hernández-Almeida
Biogeosciences, 20, 1725–1739, https://doi.org/10.5194/bg-20-1725-2023, https://doi.org/10.5194/bg-20-1725-2023, 2023
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Based on the analysis of the response of coccolithophores’ morphological attributes in a laboratory dissolution experiment and surface sediment samples from the South China Sea, we proposed that the thickness shape (ks) factor of fossil coccoliths together with the normalized ks variation, which is the ratio of the standard deviation of ks (σ) over the mean ks (σ/ks), is a robust and novel proxy to reconstruct past changes in deep ocean carbon chemistry.
Takamitsu Ito, Hernan E. Garcia, Zhankun Wang, Shoshiro Minobe, Matthew C. Long, Just Cebrian, James Reagan, Tim Boyer, Christopher Paver, Courtney Bouchard, Yohei Takano, Seth Bushinsky, Ahron Cervania, and Curtis A. Deutsch
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-72, https://doi.org/10.5194/bg-2023-72, 2023
Revised manuscript accepted for BG
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This study aims to estimate how much oceanic oxygen has been lost and its uncertainties. One major source of uncertainties comes from the statistical gap-fill methods. Outputs from earth system models are used to generate synthetic observations where oxygen data is extracted from the model output at the location and time of historical oceangraphic cruises. Reconstructed oxygen trend is approximately two thirds of the true trend.
Katherine E. Turner, Doug M. Smith, Anna Katavouta, and Richard G. Williams
Biogeosciences, 20, 1671–1690, https://doi.org/10.5194/bg-20-1671-2023, https://doi.org/10.5194/bg-20-1671-2023, 2023
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We present a new method for reconstructing ocean carbon using climate models and temperature and salinity observations. To test this method, we reconstruct modelled carbon using synthetic observations consistent with current sampling programmes. Sensitivity tests show skill in reconstructing carbon trends and variability within the upper 2000 m. Our results indicate that this method can be used for a new global estimate for ocean carbon content.
Nicole M. Travis, Colette L. Kelly, and Karen L. Casciotti
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-64, https://doi.org/10.5194/bg-2023-64, 2023
Revised manuscript accepted for BG
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We conducted experimental manipulations of light level on microbial communities from the primary nitrite maximum. Overall, while individual microbial processes have different directions and magnitudes in their response to increasing light, the net community response is a decline in nitrite production with increasing light. We conclude that while increased light may decrease net nitrite production, high light conditions alone do not exclude nitrification from occurring in the surface ocean.
Alexandre Mignot, Hervé Claustre, Gianpiero Cossarini, Fabrizio D'Ortenzio, Elodie Gutknecht, Julien Lamouroux, Paolo Lazzari, Coralie Perruche, Stefano Salon, Raphaëlle Sauzède, Vincent Taillandier, and Anna Teruzzi
Biogeosciences, 20, 1405–1422, https://doi.org/10.5194/bg-20-1405-2023, https://doi.org/10.5194/bg-20-1405-2023, 2023
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Numerical models of ocean biogeochemistry are becoming a major tool to detect and predict the impact of climate change on marine resources and monitor ocean health. Here, we demonstrate the use of the global array of BGC-Argo floats for the assessment of biogeochemical models. We first detail the handling of the BGC-Argo data set for model assessment purposes. We then present 23 assessment metrics to quantify the consistency of BGC model simulations with respect to BGC-Argo data.
Alban Planchat, Lester Kwiatkowski, Laurent Bopp, Olivier Torres, James R. Christian, Momme Butenschön, Tomas Lovato, Roland Séférian, Matthew A. Chamberlain, Olivier Aumont, Michio Watanabe, Akitomo Yamamoto, Andrew Yool, Tatiana Ilyina, Hiroyuki Tsujino, Kristen M. Krumhardt, Jörg Schwinger, Jerry Tjiputra, John P. Dunne, and Charles Stock
Biogeosciences, 20, 1195–1257, https://doi.org/10.5194/bg-20-1195-2023, https://doi.org/10.5194/bg-20-1195-2023, 2023
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Ocean alkalinity is critical to the uptake of atmospheric carbon and acidification in surface waters. We review the representation of alkalinity and the associated calcium carbonate cycle in Earth system models. While many parameterizations remain present in the latest generation of models, there is a general improvement in the simulated alkalinity distribution. This improvement is related to an increase in the export of biotic calcium carbonate, which closer resembles observations.
Jenny Hieronymus, Magnus Hieronymus, Matthias Gröger, Jörg Schwinger, Raffaele Bernadello, Etienne Tourigny, Valentina Sicardi, Itzel Ruvalcaba Baroni, and Klaus Wyser
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-54, https://doi.org/10.5194/bg-2023-54, 2023
Revised manuscript accepted for BG
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Changes in the seasonality of primary production has been examined using daily data from two earth system models covering the period 1750–2100. The daily data made it possible to detect shifts in the day of the year during which the net primary production reaches its peak value. It was found that the day of peak primary production occurs earlier and earlier during the 21st century and that a major change in the time series occurs in the beginning of the 21st century.
Jérôme Pinti, Tim DeVries, Tommy Norin, Camila Serra-Pompei, Roland Proud, David A. Siegel, Thomas Kiørboe, Colleen M. Petrik, Ken H. Andersen, Andrew S. Brierley, and André W. Visser
Biogeosciences, 20, 997–1009, https://doi.org/10.5194/bg-20-997-2023, https://doi.org/10.5194/bg-20-997-2023, 2023
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Large numbers of marine organisms such as zooplankton and fish perform daily vertical migration between the surface (at night) and the depths (in the daytime). This fascinating migration is important for the carbon cycle, as these organisms actively bring carbon to depths where it is stored away from the atmosphere for a long time. Here, we quantify the contributions of different animals to this carbon drawdown and storage and show that fish are important to the biological carbon pump.
Alastair J. M. Lough, Alessandro Tagliabue, Clément Demasy, Joseph A. Resing, Travis Mellett, Neil J. Wyatt, and Maeve C. Lohan
Biogeosciences, 20, 405–420, https://doi.org/10.5194/bg-20-405-2023, https://doi.org/10.5194/bg-20-405-2023, 2023
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Iron is a key nutrient for ocean primary productivity. Hydrothermal vents are a source of iron to the oceans, but the size of this source is poorly understood. This study examines the variability in iron inputs between hydrothermal vents in different geological settings. The vents studied release different amounts of Fe, resulting in plumes with similar dissolved iron concentrations but different particulate concentrations. This will help to refine modelling of iron-limited ocean productivity.
Nicole M. Travis, Colette L. Kelly, Margaret R. Mulholland, and Karen L. Casciotti
Biogeosciences, 20, 325–347, https://doi.org/10.5194/bg-20-325-2023, https://doi.org/10.5194/bg-20-325-2023, 2023
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The primary nitrite maximum is a ubiquitous upper ocean feature where nitrite accumulates, but we still do not understand its formation and the co-occurring microbial processes involved. Using correlative methods and rates measurements, we found strong spatial patterns between environmental conditions and depths of the nitrite maxima, but not the maximum concentrations. Nitrification was the dominant source of nitrite, with occasional high nitrite production from phytoplankton near the coast.
Natacha Le Grix, Jakob Zscheischler, Keith B. Rodgers, Ryohei Yamaguchi, and Thomas L. Frölicher
Biogeosciences, 19, 5807–5835, https://doi.org/10.5194/bg-19-5807-2022, https://doi.org/10.5194/bg-19-5807-2022, 2022
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Compound events threaten marine ecosystems. Here, we investigate the potentially harmful combination of marine heatwaves with low phytoplankton productivity. Using satellite-based observations, we show that these compound events are frequent in the low latitudes. We then investigate the drivers of these compound events using Earth system models. The models share similar drivers in the low latitudes but disagree in the high latitudes due to divergent factors limiting phytoplankton production.
Abigale M. Wyatt, Laure Resplandy, and Adrian Marchetti
Biogeosciences, 19, 5689–5705, https://doi.org/10.5194/bg-19-5689-2022, https://doi.org/10.5194/bg-19-5689-2022, 2022
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Marine heat waves (MHWs) are a frequent event in the northeast Pacific, with a large impact on the region's ecosystems. Large phytoplankton in the North Pacific Transition Zone are greatly affected by decreased nutrients, with less of an impact in the Alaskan Gyre. For small phytoplankton, MHWs increase the spring small phytoplankton population in both regions thanks to reduced light limitation. In both zones, this results in a significant decrease in the ratio of large to small phytoplankton.
Margot C. F. Debyser, Laetitia Pichevin, Robyn E. Tuerena, Paul A. Dodd, Antonia Doncila, and Raja S. Ganeshram
Biogeosciences, 19, 5499–5520, https://doi.org/10.5194/bg-19-5499-2022, https://doi.org/10.5194/bg-19-5499-2022, 2022
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We focus on the exchange of key nutrients for algae production between the Arctic and Atlantic oceans through the Fram Strait. We show that the export of dissolved silicon here is controlled by the availability of nitrate which is influenced by denitrification on Arctic shelves. We suggest that any future changes in the river inputs of silica and changes in denitrification due to climate change will impact the amount of silicon exported, with impacts on Atlantic algal productivity and ecology.
Emily J. Zakem, Barbara Bayer, Wei Qin, Alyson E. Santoro, Yao Zhang, and Naomi M. Levine
Biogeosciences, 19, 5401–5418, https://doi.org/10.5194/bg-19-5401-2022, https://doi.org/10.5194/bg-19-5401-2022, 2022
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We use a microbial ecosystem model to quantitatively explain the mechanisms controlling observed relative abundances and nitrification rates of ammonia- and nitrite-oxidizing microorganisms in the ocean. We also estimate how much global carbon fixation can be associated with chemoautotrophic nitrification. Our results improve our understanding of the controls on nitrification, laying the groundwork for more accurate predictions in global climate models.
Zuozhu Wen, Thomas J. Browning, Rongbo Dai, Wenwei Wu, Weiying Li, Xiaohua Hu, Wenfang Lin, Lifang Wang, Xin Liu, Zhimian Cao, Haizheng Hong, and Dalin Shi
Biogeosciences, 19, 5237–5250, https://doi.org/10.5194/bg-19-5237-2022, https://doi.org/10.5194/bg-19-5237-2022, 2022
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Fe and P are key factors controlling the biogeography and activity of marine N2-fixing microorganisms. We found lower abundance and activity of N2 fixers in the northern South China Sea than around the western boundary of the North Pacific, and N2 fixation rates switched from Fe–P co-limitation to P limitation. We hypothesize the Fe supply rates and Fe utilization strategies of each N2 fixer are important in regulating spatial variability in community structure across the study area.
Claudia Eisenring, Sophy E. Oliver, Samar Khatiwala, and Gregory F. de Souza
Biogeosciences, 19, 5079–5106, https://doi.org/10.5194/bg-19-5079-2022, https://doi.org/10.5194/bg-19-5079-2022, 2022
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Given the sparsity of observational constraints on micronutrients such as zinc (Zn), we assess the sensitivities of a framework for objective parameter optimisation in an oceanic Zn cycling model. Our ensemble of optimisations towards synthetic data with varying kinds of uncertainty shows that deficiencies related to model complexity and the choice of the misfit function generally have a greater impact on the retrieval of model Zn uptake behaviour than does the limitation of data coverage.
Yoshikazu Sasai, Sherwood Lan Smith, Eko Siswanto, Hideharu Sasaki, and Masami Nonaka
Biogeosciences, 19, 4865–4882, https://doi.org/10.5194/bg-19-4865-2022, https://doi.org/10.5194/bg-19-4865-2022, 2022
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We have investigated the adaptive response of phytoplankton growth to changing light, nutrients, and temperature over the North Pacific using two physical-biological models. We compare modeled chlorophyll and primary production from an inflexible control model (InFlexPFT), which assumes fixed carbon (C):nitrogen (N):chlorophyll (Chl) ratios, to a recently developed flexible phytoplankton functional type model (FlexPFT), which incorporates photoacclimation and variable C:N:Chl ratios.
Jens Terhaar, Thomas L. Frölicher, and Fortunat Joos
Biogeosciences, 19, 4431–4457, https://doi.org/10.5194/bg-19-4431-2022, https://doi.org/10.5194/bg-19-4431-2022, 2022
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Estimates of the ocean sink of anthropogenic carbon vary across various approaches. We show that the global ocean carbon sink can be estimated by three parameters, two of which approximate the ocean ventilation in the Southern Ocean and the North Atlantic, and one of which approximates the chemical capacity of the ocean to take up carbon. With observations of these parameters, we estimate that the global ocean carbon sink is 10 % larger than previously assumed, and we cut uncertainties in half.
Natasha René van Horsten, Hélène Planquette, Géraldine Sarthou, Thomas James Ryan-Keogh, Nolwenn Lemaitre, Thato Nicholas Mtshali, Alakendra Roychoudhury, and Eva Bucciarelli
Biogeosciences, 19, 3209–3224, https://doi.org/10.5194/bg-19-3209-2022, https://doi.org/10.5194/bg-19-3209-2022, 2022
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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 carbon remineralisation from satellite data on a basin scale.
Zhibo Shao and Ya-Wei Luo
Biogeosciences, 19, 2939–2952, https://doi.org/10.5194/bg-19-2939-2022, https://doi.org/10.5194/bg-19-2939-2022, 2022
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Non-cyanobacterial diazotrophs (NCDs) may be an important player in fixing N2 in the ocean. By conducting meta-analyses, we found that a representative marine NCD phylotype, Gamma A, tends to inhabit ocean environments with high productivity, low iron concentration and high light intensity. It also appears to be more abundant inside cyclonic eddies. Our study suggests a niche differentiation of NCDs from cyanobacterial diazotrophs as the latter prefers low-productivity and high-iron oceans.
Coraline Leseurre, Claire Lo Monaco, Gilles Reverdin, Nicolas Metzl, Jonathan Fin, Claude Mignon, and Léa Benito
Biogeosciences, 19, 2599–2625, https://doi.org/10.5194/bg-19-2599-2022, https://doi.org/10.5194/bg-19-2599-2022, 2022
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Decadal trends of fugacity of CO2 (fCO2), total alkalinity (AT), total carbon (CT) and pH in surface waters are investigated in different domains of the southern Indian Ocean (45°S–57°S) from ongoing and station observations regularly conducted in summer over the period 1998–2019. The fCO2 increase and pH decrease are mainly driven by anthropogenic CO2 estimated just below the summer mixed layer, as well as by a warming south of the polar front or in the fertilized waters near Kerguelen Island.
Priscilla Le Mézo, Jérôme Guiet, Kim Scherrer, Daniele Bianchi, and Eric Galbraith
Biogeosciences, 19, 2537–2555, https://doi.org/10.5194/bg-19-2537-2022, https://doi.org/10.5194/bg-19-2537-2022, 2022
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This study quantifies the role of commercially targeted fish biomass in the cycling of three important nutrients (N, P, and Fe), relative to nutrients otherwise available in water and to nutrients required by primary producers, and the impact of fishing. We use a model of commercially targeted fish biomass constrained by fish catch and stock assessment data to assess the contributions of fish at the global scale, at the time of the global peak catch and prior to industrial fishing.
Rebecca Chmiel, Nathan Lanning, Allison Laubach, Jong-Mi Lee, Jessica Fitzsimmons, Mariko Hatta, William Jenkins, Phoebe Lam, Matthew McIlvin, Alessandro Tagliabue, and Mak Saito
Biogeosciences, 19, 2365–2395, https://doi.org/10.5194/bg-19-2365-2022, https://doi.org/10.5194/bg-19-2365-2022, 2022
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Dissolved cobalt is present in trace amounts in seawater and is a necessary nutrient for marine microbes. On a transect from the Alaskan coast to Tahiti, we measured seawater concentrations of dissolved cobalt. Here, we describe several interesting features of the Pacific cobalt cycle including cobalt sources along the Alaskan coast and Hawaiian vents, deep-ocean particle formation, cobalt activity in low-oxygen regions, and how our samples compare to a global biogeochemical model’s predictions.
Nicolas Metzl, Claire Lo Monaco, Coraline Leseurre, Céline Ridame, Jonathan Fin, Claude Mignon, Marion Gehlen, and Thi Tuyet Trang Chau
Biogeosciences, 19, 1451–1468, https://doi.org/10.5194/bg-19-1451-2022, https://doi.org/10.5194/bg-19-1451-2022, 2022
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During an oceanographic cruise conducted in January 2020 in the south-western Indian Ocean, we observed very low CO2 concentrations associated with a strong phytoplankton bloom that occurred south-east of Madagascar. This biological event led to a strong regional CO2 ocean sink not previously observed.
Darren R. Clark, Andrew P. Rees, Charissa M. Ferrera, Lisa Al-Moosawi, Paul J. Somerfield, Carolyn Harris, Graham D. Quartly, Stephen Goult, Glen Tarran, and Gennadi Lessin
Biogeosciences, 19, 1355–1376, https://doi.org/10.5194/bg-19-1355-2022, https://doi.org/10.5194/bg-19-1355-2022, 2022
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Measurements of microbial processes were made in the sunlit open ocean during a research cruise (AMT19) between the UK and Chile. These help us to understand how microbial communities maintain the function of remote ecosystems. We find that the nitrogen cycling microbes which produce nitrite respond to changes in the environment. Our insights will aid the development of models that aim to replicate and ultimately project how marine environments may respond to ongoing climate change.
Martí Galí, Marcus Falls, Hervé Claustre, Olivier Aumont, and Raffaele Bernardello
Biogeosciences, 19, 1245–1275, https://doi.org/10.5194/bg-19-1245-2022, https://doi.org/10.5194/bg-19-1245-2022, 2022
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Part of the organic matter produced by plankton in the upper ocean is exported to the deep ocean. This process, known as the biological carbon pump, is key for the regulation of atmospheric carbon dioxide and global climate. However, the dynamics of organic particles below the upper ocean layer are not well understood. Here we compared the measurements acquired by autonomous robots in the top 1000 m of the ocean to a numerical model, which can help improve future climate projections.
Marie Barbieux, Julia Uitz, Alexandre Mignot, Collin Roesler, Hervé Claustre, Bernard Gentili, Vincent Taillandier, Fabrizio D'Ortenzio, Hubert Loisel, Antoine Poteau, Edouard Leymarie, Christophe Penkerc'h, Catherine Schmechtig, and Annick Bricaud
Biogeosciences, 19, 1165–1194, https://doi.org/10.5194/bg-19-1165-2022, https://doi.org/10.5194/bg-19-1165-2022, 2022
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This study assesses marine biological production in two Mediterranean systems representative of vast desert-like (oligotrophic) areas encountered in the global ocean. We use a novel approach based on non-intrusive high-frequency in situ measurements by two profiling robots, the BioGeoChemical-Argo (BGC-Argo) floats. Our results indicate substantial yet variable production rates and contribution to the whole water column of the subsurface layer, typically considered steady and non-productive.
Filippa Fransner, Friederike Fröb, Jerry Tjiputra, Nadine Goris, Siv K. Lauvset, Ingunn Skjelvan, Emil Jeansson, Abdirahman Omar, Melissa Chierici, Elizabeth Jones, Agneta Fransson, Sólveig R. Ólafsdóttir, Truls Johannessen, and Are Olsen
Biogeosciences, 19, 979–1012, https://doi.org/10.5194/bg-19-979-2022, https://doi.org/10.5194/bg-19-979-2022, 2022
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Ocean acidification, a direct consequence of the CO2 release by human activities, is a serious threat to marine ecosystems. In this study, we conduct a detailed investigation of the acidification of the Nordic Seas, from 1850 to 2100, by using a large set of samples taken during research cruises together with numerical model simulations. We estimate the effects of changes in different environmental factors on the rate of acidification and its potential effects on cold-water corals.
Guorong Zhong, Xuegang Li, Jinming Song, Baoxiao Qu, Fan Wang, Yanjun Wang, Bin Zhang, Xiaoxia Sun, Wuchang Zhang, Zhenyan Wang, Jun Ma, Huamao Yuan, and Liqin Duan
Biogeosciences, 19, 845–859, https://doi.org/10.5194/bg-19-845-2022, https://doi.org/10.5194/bg-19-845-2022, 2022
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A predictor selection algorithm was constructed to decrease the predicting error in the surface ocean partial pressure of CO2 (pCO2) mapping by finding better combinations of pCO2 predictors in different regions. Compared with previous research using the same combination of predictors in all regions, using different predictors selected by the algorithm in different regions can effectively decrease pCO2 predicting errors.
Shantelle Smith, Katye E. Altieri, Mhlangabezi Mdutyana, David R. Walker, Ruan G. Parrott, Sedick Gallie, Kurt A. M. Spence, Jessica M. Burger, and Sarah E. Fawcett
Biogeosciences, 19, 715–741, https://doi.org/10.5194/bg-19-715-2022, https://doi.org/10.5194/bg-19-715-2022, 2022
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Ammonium is a crucial yet poorly understood component of the Southern Ocean nitrogen cycle. We attribute our finding of consistently high ammonium concentrations in the winter mixed layer to limited ammonium consumption and sustained ammonium production, conditions under which the Southern Ocean becomes a source of carbon dioxide to the atmosphere. From similar data collected over an annual cycle, we propose a seasonal cycle for ammonium in shallow polar waters – a first for the Southern Ocean.
Jannes Koelling, Dariia Atamanchuk, Johannes Karstensen, Patricia Handmann, and Douglas W. R. Wallace
Biogeosciences, 19, 437–454, https://doi.org/10.5194/bg-19-437-2022, https://doi.org/10.5194/bg-19-437-2022, 2022
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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
Short summary
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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
Short summary
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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
Short summary
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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.
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Short summary
Surface waters of the western tropical South Pacific were sampled along a longitudinal 4000 km transect during the stratified period between the Melanesian Archipelago and the western part of the South Pacific gyre. We found a significant biological carbon pump sustained almost exclusively by N2 fixation and essentially controlled by phosphate availability in the iron-rich Melanesian Archipelago waters which appears to be a net sink for atmospheric CO2 while the gyre is in a quasi-steady state.
Surface waters of the western tropical South Pacific were sampled along a longitudinal 4000 km...
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