Tag Archive for: biologic carbon pump

The ocean may be storing more carbon than estimated in previous studies

, , , ,

Our colleague Frédéric Le Moigne contributed to an international study on the efficiency of the oceanic carbon pump. The study, published this week in Nature magazine, reassesses the ocean’s capacity to store carbon, particularly through ‘marine snow’. The CNRS issued a press release about this publication :

The ocean’s capacity to store atmospheric carbon dioxide is almost 20% higher than the estimates presented in the latest IPCC report. These are the findings of a study published in the journal Nature on 6 December 2023 by an international team including a biologist from the CNRS. The scientists looked at the role played by plankton in the natural transport of carbon from the surface to the seabed.

Plankton is fond of this gas, which it transforms into organic tissue through photosynthesis during its development, and some of it is transformed into marine particles at the end of its life. Denser than seawater, this ‘marine snow’ sinks to the seabed, storing carbon and providing essential nutrients for many deep-sea creatures, from tiny bacteria to deep-sea fish.

Based on the study of a database collected from around the world since the 1970s using oceanographic vessels, the team of seven scientists were able to digitally map the fluxes of organic matter throughout the oceans. The resulting new estimate of storage capacity is 15 gigatonnes per year, an increase of around 20% on the previous studies (11 gigatonnes per year) reported by the IPCC in its 2021 report.

This reassessment of the seabed’s storage capacity represents a significant advance in our understanding of carbon exchanges between the atmosphere and the ocean at a global level. While the team stresses that this absorption process takes place over tens of thousands of years, and is therefore not sufficient to offset the exponential increase in CO2 emissions generated by global industrial activity since 1750, this study nevertheless reinforces the importance of the ocean ecosystem as a major player in regulating the global climate in the long term.

Global distribution of organic carbon flux from the surface layer of the open ocean.
© Wang et al., 2023, Nature.

 

Reference:

Biological carbon pump estimate based on multi-decadal hydrographic data. Wei-Lei Wang, Weiwei Fu, Frédéric A. C. Le Moigne, Robert T. Letscher, Yi Liu, Jin-Ming Tang, and François W. Primeau. Nature, le 6 décembre 2023.
DOI : https://doi.org/10.1038/s41586-023-06772-4

Carbon fate in the deep ocean

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The biological carbon pump can be broken down into three stages: the formation of biogenic carbon at the surface (production), the transfer below the mixed layer (export) and the attenuation of the flux in the mesopelagic zone (200-2000 m), towards long-term storage (> 1000 years) in the deep ocean and sediments. For operational reasons, the years 1980-2000 were strongly focused on the first two components of the biological pump (international JGOFS programme). The depth of carbon flux attenuation with depth, which imposes strong constraints on the time scales of carbon storage in the deep ocean, is constrained by ocean dynamics (turbulence, small scales, etc.), dissolution processes, biological activity (heterotrophic activity, respiration) and particle behaviour (sedimentation, aggregation/desaggregation). The evolution of observation means (autonomous platforms, high frequency measurements, acoustics, imaging, molecular biology, etc.), as well as progress in modelling (computer power, taking complexity into account, Artificial Intelligence), now make it possible to tackle this question head-on. LEMAR is fully involved in this new dynamic and relies on its expertise in the description of the fate of dissolved organic matter, the silicon, iron and carbon cycles, the role of zooplankton, remineralisation processes, particle dynamics, the study of the small scale in the mesopelagic zone (see AR2. 1 CHIBIDO), modelling (in connection with the ITM Atlantic teams developing approaches in Artificial Intelligence), microbiology or ecology to get involved and carry out international projects on this topic. In addition, the laboratory actively participated in the creation of the international consortium JETZON (Joint Exploration of the Twilight Zone Ocean Network: https://jetzon.org/) coordinating programmes on the mesopelagic zone.

Influence of diatom diversity on the ocean biological carbon pump

Abstract

Diatoms sustain the marine food web and contribute to the export of carbon from the surface ocean to depth. They account for about 40% of marine primary productivity and particulate carbon exported to depth as part of the biological pump. Diatoms have long been known to be abundant in turbulent, nutrient-rich waters, but observations and simulations indicate that they are dominant also in meso- and submesoscale structures such as fronts and filaments, and in the deep chlorophyll maximum. Diatoms vary widely in size, morphology and elemental composition, all of which control the quality, quantity and sinking speed of biogenic matter to depth. In particular, their silica shells provide ballast to marine snow and faecal pellets, and can help transport carbon to both the mesopelagic layer and deep ocean. Herein we show that the extent to which diatoms contribute to the export of carbon varies by diatom type, with carbon transfer modulated by the Si/C ratio of diatom cells, the thickness of the shells and their life strategies; for instance, the tendency to form aggregates or resting spores. Model simulations project a decline in the contribution of diatoms to primary production everywhere outside of the Southern Ocean. We argue that we need to understand changes in diatom diversity, life cycle and plankton interactions in a warmer and more acidic ocean in much more detail to fully assess any changes in their contribution to the biological pump.

 

Graphical abstract

Reference

Tréguer, P., Bowler, C., Moriceau, B., Dutkiewicz, S., Gehlen, M., Aumont, O., Bittner,L., Dugdale, R., Finkel, Z., Ludicone, D., Jahn,O., Guidi, L., Lasbleiz, M., Leblanc, K., Levy, M. & Pondaven, P. (2017). Influence of diatom diversity on the ocean biological carbon pump. Nature Geoscience 11, 27–37 (2017). doi:10.1038/s41561-017-0028-x

Tag Archive for: biologic carbon pump

Frédéric LE MOIGNE

,

Tag Archive for: biologic carbon pump

APERO

,

Frigo

,

Tag Archive for: biologic carbon pump

Chibido team

Team

Chibido

Marine chemistry, biogeochemical cycles and ocean dynamics

The marine biogeochemical cycles of the major and trace elements play fundamental roles in both the biological and chemical functioning of the ocean but also in terrestrial climatic regulation. Marine ecosystems (phytoplankton, zooplankton, bacteria, fish, predators) occupy a central place within these cycles and contribute by various processes (assimilation-degradation-trophic transfer-sedimentation) to transform, store and redistribute the chemical elements in the column. of ocean water. These transformations favor different levels of coupling between the element cycles and interact directly on the climate by modifying the gas exchanges involved in the radiative balance of the atmosphere (CO2, CH4, N2O, DMS). Despite significant progress made in recent decades, this essential role of marine ecosystems on biogeochemical cycles and ultimately on the climate remains poorly quantified and is still a scientific issue.

This issue is all the more important in the current context in which anthropogenic pressures on the ocean and marine organisms continue to increase and multiply. Climate change and modification of environmental forcings (T, pH, pCO2, currents, extension of sea ice), releases of polluting substances (toxic metals, pesticides, microplastics, etc.), intensive exploitation of biological resources or the degradation of natural habitats are all factors that can profoundly alter the structure, functioning and biodiversity of marine ecosystems. What will be the impacts of these modifications on biogeochemical cycles, ocean productivity, gas exchanges? What will be the climate feedbacks and organizations’ response to these changes? These are all questions that the scientific community must answer if it intends to reduce the uncertainties associated with climate simulations and anticipate the joint evolution of marine ecosystems.

It is around these questions that our research team (CHIBIDO) develops its activities. Our objects of study are the biogeochemical cycles of the major elements (C, N, P, S, Si) and metallic traces (Fe, Mn, Cu, Ni, Zn, Co, Cd, Mo, Pb) and we try, by multidisciplinary approaches involving physicists, biologists, chemists and modelers to contribute to the improvement of knowledge on the interactions between oceanic dynamics, biogeochemical cycles, ecosystems and climate. Our research actions combine a wide spectrum of approaches associating the development of new methods of analysis (multi-elementary, isotopic and speciation), the implementation of tracers / geochemical proxies (Baxs, 234Th, δ30Si, δ11B), in situ observation at different scales (microcosms, mesocosms, basin, global), laboratory experimentation and the use of numerical modeling. These approaches are part of the international (IMBER, GEOTRACES, SOLAS) and national (LEFE-CYBER, EC2CO / DRIL, LABEX Sea) programmatic framework and are structured along three lines of research:

chibido - Axes des recherche

Axes de recherche de l’équipe Chibido.


Animation: Olivier Ragueneau & Gabriel Dulaquais

A better understanding of oceanic biogeochemical cycles requires describing and understanding input and output, and their variability. To this end, we are working on the different interfaces with the ocean, since these interfaces are external sources and sinks of matter whose intensity and importance vary according to the element considered. These interfaces are generally the site of strong physico-chemical gradients and are extremely sensitive to different anthropogenic pressures.

Sediments, the ocean-atmosphere interface, and hydrothermal springs are the sources of metals for the ocean. Our findings showing that bacterial concentrations in rainwater samples are related to the increase in iron-specific ligand concentrations that can impact organic speciation of iron, our objective is to better understand the interactions between iron and bioaerosols and their fate in the ocean water column. In hydrothermal environments, our objective is to identify and describe the chemical reactions that determine the organic complexing of metals.

The land-sea continuum is an interface strongly impacted by anthropogenic pressures. The physico-chemical gradients in estuaries control river inputs of biogenic (Si, N) and metallic elements. Our team continues to improve our understanding of the dynamics of these elements along the land-sea continuum by studying the changes that occur through adsorption/desorption, coagulation, complexing or degradation processes and by characterizing the composition and physico-chemical role of organic matter that influences their bioavailability/toxicity.

In addition, our work in the Bay of Vilaine should lead us to participate in the development of a nutrient limitation scheme that could restore eutrophic ecosystems. By improving our knowledge of the Brest Rade we wish to use climate change scenarios to model the evolution of nutrient fluxes in the coastal zone. These scenarios can be combined with scenarios of changes in agricultural practices in the watersheds in collaboration with AMURE’s team of economists.

 

Animation: Pascal Rivière & Eva Bucciarelli 

In this RA, we are seeking to better understand the spatial and temporal variability of phytoplankton production in relation to cycle dynamics and small-scale hydrodynamic structures. To do this, we have targeted several objectives

(1) to observe and describe the distributions and chemical speciation of dissolved and particulate trace metals during major international oceanographic cruises

(2) to study factors such as limitations or toxicity and pressures that will control the internal dynamics of biogenic elements (N, Si, metals) in relation to phytoplankton physiology and phytoplankton community structure in collaboration with Team 2

(3) to link small-scale dynamic structures and planktonic biodiversity.

To achieve these objectives, we combine different approaches involving in situ observation within the framework of international (GEOTRACES) and national programs (biologging and sea elephants CNES-TOSCA ) or from the LAbexMer and EUR ISblue (M2BIPAT), laboratory and natural environment process studies (isotopic techniques), as well as 3D ocean circulation models (NEMO, CROCO) coupled with biogeochemical models (PISCES, DARWIN, DARWIN-QUOTA) to understand planktonic diversity.

Animation : Laurent Mémery

In close connection with ISBLUE Theme 1, the objectives of this axis are to study the factors controlling the nature, amplitude, and mitigation of carbon export fluxes from the surface to the deep ocean. Emphasis is placed on the processes of particle formation (biological and physical aggregation), vertical export (proxy 234Th), mesopelagic remineralization (proxy Baxs) and trophic interactions with microbial and zooplankton communities. Despite the progress made by recent models that increasingly take into account the processes controlling export, such as size classes and zooplankton behaviour, there is still a need to improve our understanding of particle dynamics and the factors affecting particle size and number, their sink rate and their fate in the mesopalagic zone. To this end, our approach includes in situ measurement campaigns using geochemical proxies, as well as process studies more specifically related to processes impacting particle dynamics in mesopelagic zones and various modelling tools.

Team leaders


Researchers and teachers


Paul Treguer

engineers and technicians


PhD students


Post-doctoral positions


The ocean may be storing more carbon than estimated in previous studies

, , , ,

Our colleague Frédéric Le Moigne contributed to an international study on the efficiency of the oceanic carbon pump. The study, published this week in Nature magazine, reassesses the ocean’s capacity to store carbon, particularly through ‘marine snow’. The CNRS issued a press release about this publication :

The ocean’s capacity to store atmospheric carbon dioxide is almost 20% higher than the estimates presented in the latest IPCC report. These are the findings of a study published in the journal Nature on 6 December 2023 by an international team including a biologist from the CNRS. The scientists looked at the role played by plankton in the natural transport of carbon from the surface to the seabed.

Plankton is fond of this gas, which it transforms into organic tissue through photosynthesis during its development, and some of it is transformed into marine particles at the end of its life. Denser than seawater, this ‘marine snow’ sinks to the seabed, storing carbon and providing essential nutrients for many deep-sea creatures, from tiny bacteria to deep-sea fish.

Based on the study of a database collected from around the world since the 1970s using oceanographic vessels, the team of seven scientists were able to digitally map the fluxes of organic matter throughout the oceans. The resulting new estimate of storage capacity is 15 gigatonnes per year, an increase of around 20% on the previous studies (11 gigatonnes per year) reported by the IPCC in its 2021 report.

This reassessment of the seabed’s storage capacity represents a significant advance in our understanding of carbon exchanges between the atmosphere and the ocean at a global level. While the team stresses that this absorption process takes place over tens of thousands of years, and is therefore not sufficient to offset the exponential increase in CO2 emissions generated by global industrial activity since 1750, this study nevertheless reinforces the importance of the ocean ecosystem as a major player in regulating the global climate in the long term.

Global distribution of organic carbon flux from the surface layer of the open ocean.
© Wang et al., 2023, Nature.

 

Reference:

Biological carbon pump estimate based on multi-decadal hydrographic data. Wei-Lei Wang, Weiwei Fu, Frédéric A. C. Le Moigne, Robert T. Letscher, Yi Liu, Jin-Ming Tang, and François W. Primeau. Nature, le 6 décembre 2023.
DOI : https://doi.org/10.1038/s41586-023-06772-4

Frédéric LE MOIGNE

,

APERO

,

Frigo

,

Chibido team

Team

Chibido

Marine chemistry, biogeochemical cycles and ocean dynamics

The marine biogeochemical cycles of the major and trace elements play fundamental roles in both the biological and chemical functioning of the ocean but also in terrestrial climatic regulation. Marine ecosystems (phytoplankton, zooplankton, bacteria, fish, predators) occupy a central place within these cycles and contribute by various processes (assimilation-degradation-trophic transfer-sedimentation) to transform, store and redistribute the chemical elements in the column. of ocean water. These transformations favor different levels of coupling between the element cycles and interact directly on the climate by modifying the gas exchanges involved in the radiative balance of the atmosphere (CO2, CH4, N2O, DMS). Despite significant progress made in recent decades, this essential role of marine ecosystems on biogeochemical cycles and ultimately on the climate remains poorly quantified and is still a scientific issue.

This issue is all the more important in the current context in which anthropogenic pressures on the ocean and marine organisms continue to increase and multiply. Climate change and modification of environmental forcings (T, pH, pCO2, currents, extension of sea ice), releases of polluting substances (toxic metals, pesticides, microplastics, etc.), intensive exploitation of biological resources or the degradation of natural habitats are all factors that can profoundly alter the structure, functioning and biodiversity of marine ecosystems. What will be the impacts of these modifications on biogeochemical cycles, ocean productivity, gas exchanges? What will be the climate feedbacks and organizations’ response to these changes? These are all questions that the scientific community must answer if it intends to reduce the uncertainties associated with climate simulations and anticipate the joint evolution of marine ecosystems.

It is around these questions that our research team (CHIBIDO) develops its activities. Our objects of study are the biogeochemical cycles of the major elements (C, N, P, S, Si) and metallic traces (Fe, Mn, Cu, Ni, Zn, Co, Cd, Mo, Pb) and we try, by multidisciplinary approaches involving physicists, biologists, chemists and modelers to contribute to the improvement of knowledge on the interactions between oceanic dynamics, biogeochemical cycles, ecosystems and climate. Our research actions combine a wide spectrum of approaches associating the development of new methods of analysis (multi-elementary, isotopic and speciation), the implementation of tracers / geochemical proxies (Baxs, 234Th, δ30Si, δ11B), in situ observation at different scales (microcosms, mesocosms, basin, global), laboratory experimentation and the use of numerical modeling. These approaches are part of the international (IMBER, GEOTRACES, SOLAS) and national (LEFE-CYBER, EC2CO / DRIL, LABEX Sea) programmatic framework and are structured along three lines of research:

chibido - Axes des recherche

Axes de recherche de l’équipe Chibido.


Animation: Olivier Ragueneau & Gabriel Dulaquais

A better understanding of oceanic biogeochemical cycles requires describing and understanding input and output, and their variability. To this end, we are working on the different interfaces with the ocean, since these interfaces are external sources and sinks of matter whose intensity and importance vary according to the element considered. These interfaces are generally the site of strong physico-chemical gradients and are extremely sensitive to different anthropogenic pressures.

Sediments, the ocean-atmosphere interface, and hydrothermal springs are the sources of metals for the ocean. Our findings showing that bacterial concentrations in rainwater samples are related to the increase in iron-specific ligand concentrations that can impact organic speciation of iron, our objective is to better understand the interactions between iron and bioaerosols and their fate in the ocean water column. In hydrothermal environments, our objective is to identify and describe the chemical reactions that determine the organic complexing of metals.

The land-sea continuum is an interface strongly impacted by anthropogenic pressures. The physico-chemical gradients in estuaries control river inputs of biogenic (Si, N) and metallic elements. Our team continues to improve our understanding of the dynamics of these elements along the land-sea continuum by studying the changes that occur through adsorption/desorption, coagulation, complexing or degradation processes and by characterizing the composition and physico-chemical role of organic matter that influences their bioavailability/toxicity.

In addition, our work in the Bay of Vilaine should lead us to participate in the development of a nutrient limitation scheme that could restore eutrophic ecosystems. By improving our knowledge of the Brest Rade we wish to use climate change scenarios to model the evolution of nutrient fluxes in the coastal zone. These scenarios can be combined with scenarios of changes in agricultural practices in the watersheds in collaboration with AMURE’s team of economists.

 

Animation: Pascal Rivière & Eva Bucciarelli 

In this RA, we are seeking to better understand the spatial and temporal variability of phytoplankton production in relation to cycle dynamics and small-scale hydrodynamic structures. To do this, we have targeted several objectives

(1) to observe and describe the distributions and chemical speciation of dissolved and particulate trace metals during major international oceanographic cruises

(2) to study factors such as limitations or toxicity and pressures that will control the internal dynamics of biogenic elements (N, Si, metals) in relation to phytoplankton physiology and phytoplankton community structure in collaboration with Team 2

(3) to link small-scale dynamic structures and planktonic biodiversity.

To achieve these objectives, we combine different approaches involving in situ observation within the framework of international (GEOTRACES) and national programs (biologging and sea elephants CNES-TOSCA ) or from the LAbexMer and EUR ISblue (M2BIPAT), laboratory and natural environment process studies (isotopic techniques), as well as 3D ocean circulation models (NEMO, CROCO) coupled with biogeochemical models (PISCES, DARWIN, DARWIN-QUOTA) to understand planktonic diversity.

Animation : Laurent Mémery

In close connection with ISBLUE Theme 1, the objectives of this axis are to study the factors controlling the nature, amplitude, and mitigation of carbon export fluxes from the surface to the deep ocean. Emphasis is placed on the processes of particle formation (biological and physical aggregation), vertical export (proxy 234Th), mesopelagic remineralization (proxy Baxs) and trophic interactions with microbial and zooplankton communities. Despite the progress made by recent models that increasingly take into account the processes controlling export, such as size classes and zooplankton behaviour, there is still a need to improve our understanding of particle dynamics and the factors affecting particle size and number, their sink rate and their fate in the mesopalagic zone. To this end, our approach includes in situ measurement campaigns using geochemical proxies, as well as process studies more specifically related to processes impacting particle dynamics in mesopelagic zones and various modelling tools.

Team leaders


Researchers and teachers


Paul Treguer

engineers and technicians


PhD students


Post-doctoral positions