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The research groups - Oceans

Université Libre de Bruxelles (ULB)
Ecologie des Systèmes Aquatiques (ESA-ULB)
Promotor: Prof. Lancelot Christiane

Presentation

ESA (Ecologie des Systèmes Aquatiques) is a research unit of the Université Libre de Bruxelles. It is active since 20 years in the study of general aspects of aquatic microbial ecology and has published some 300 papers in international peer-reviewed journals. ESA is currently developing an integrated conceptual methodological approach combining field observations, process-level studies and numerical experimentation that aims to develop a generic mechanistic biogeochemical model of the planktonic ecosystem based on physiological and geochemical principles. When coupled with hydrodynamical models of appropriate spatio-temporal resolution, such a model can address local, regional or more global environmental questions such as the uptake of atmospheric CO2 by the Southern Ocean. To comply with the interdisciplinary nature of its environmental research, ESA is continuously developing national and international collaborations in the scope of joint research projects and membership of international scientific committees or through PhD-student and post-doc exchanges.

ESA has the expertise in (i) the study of the microbiological processes in the polar environment and (ii) the development of complex biogeochemical model that can be coupled to ice-ocean 1D and 3D models. To achieve these objectives, ESA is well equipped with laboratory infrastructures required for microbiological studies: temperature and light-controlled culture room, laminar-flow bench, facilities for radio-isotopes work (radioactive room, scintillation counter), microscopes (inverted and epifluorescence) and image analyser, spectrofluorometer, photometer, TOC analyser, optic sensors and molecular biology equipments. For the polar environmental studies, ESA has developed specific methodologies to measure microbiological and biogeochemical processes in the extreme environments and making use of ultraclean techniques to avoid trace metal contamination. In particular, ESA has a temperature- and light- controlled culture room with phytoplankton collection including diatoms and Phaeocystis antarctica maintained at 0°C and a trace-metal clean room. More than 15 years of activity in Antarctic research, has allowed the successful development and testing of the biogeochemical SWAMCO model (describing the C, N, P, Si, Fe cycling through different aggregated chemical and biological compartments of the Antarctic plankton ecosystem) which has been implemented in a 1D and 3D physical resolution.

Activities

ESA was invited to participate to several international polar expeditions in the Southern Ocean (EPOS-European Polarstern Study, and SO-JGOFS expeditions; AntX/6 and AntXVI/3, Antares 2 and 3, AESOPS-process-IV, ARISE, ISPOL) and in Arctic Fjords. ESA was also actively present at all international Polar conference such as the 5 Gordon Conferences on Polar Marine Science, the SO-JGOFS symposia of Brest (France), the special sessions on polar research held during ASLO meetings.

ESA-ULB contributes also to:

  • PADD-II-Support actions: SOLAS cluster. 2005-2007
  • PADD- II-Support actions: BE-POLE cluster. 2005-2007
  • Federal Science Policy: Scientific secretariat of Focus 1 of international SOLAS (Surface Ocean-Lower Atmosphere Study)

Main field of activity in polar regions

ESA research focuses on the study and modelling of the response of marine ecosystems to climate and anthropogenic changes. This happens throughout the understanding of the interactions between planktonic organisms and marine biogeochemical cycles (C, N, P, Si, Fe). To achieve this objective ESA research activities aim to assess the contribution of biological processes to air-ice-sea exchanges of CO2 and DMS in the Southern Ocean.

(i) Sea ice and pelagic microbial eco-physiology in the Southern Ocean

Biological activities of the Ocean can significantly affect the greenhouse gas, such as CO2. Algae produces particulate organic matter by the photosynthetic uptake of CO2 and such particles may sink away from the surface. In this biological process, there is a net transfer of CO2 from surface waters into the deeper parts of the ocean (carbon biological pump). Major part of the organic carbon is decomposed during sinking and can return to the surface by upwellings. However, another part of the organic carbon is sequestrated into the deep ocean. The efficiency of carbon biological pump relies not only on the level of primary production (photosynthetic CO2 uptake by phytoplankton) but also on the dominant phytoplanktonic groups which shape the structure of the pelagic food web (microbial food web versus classical linear food chain) and which are characterised by different biodegradability and aggregation potential and sinking rates.
In the HNLC (High Nutrients Low Chlorophyll) waters of the Southern Ocean, iron (Fe) has been shown to play a key role in limiting phytoplankton productivity and in structuring the planktonic communities. It is now known that the carbon transfer efficiency via the biological pump might be controlled by iron availability.
Recently, it has recently been shown that Fe can accumulate in the sea ice. In sea-ice associated ecosystems, sea ice might thus represent a significant source of iron for the pelagic food-web.
The role of microbial processes in the biochemical cycles of C, Fe, N, P, Si is being investigated through field observations in both pelagic and sea-ice ecosystems and via field and laboratory process-level studies.
Our specific objectives are to investigate:

  • Fe-organic matter interactions and their impact on Fe bioavailability
  • The effect of iron availability on algae eco-physiology
  • The co-limitation of iron and carbon on the bacterial remineralisation
  • The structure and functioning of the microbial network and its interaction on biogeochemical cycles

(ii) The biogeochemical model SWAMCO.

More than 15 year of activity in Antarctic research, has allowed the successful development and testing of the biogeochemical SWAMCO-4 model. The SWAMCO-4 model is a complex mechanistic model of the marine planktonic system describing C, N, P, Si, Fe cycling within the upper ocean, the export production and the exchange of CO2 between Ocean and atmosphere. The model constrained by physical, chemical and biological (grazing and lysis) controls, explicitly details the dynamic of four relevant phytoplankton functional groups with respect to C, N, P, Si, Fe cycling and climate change. These are diatoms, autotrophic pico-nanophytoplankton, coccolithophorids and Phaeocystis sp., distinguished on the basis of their physiology (temperature and light adaptation, nutrient and iron uptake kinetics and sinking rates) and mode of grazer control (microzooplankton and mesozooplanton).
The performance of the SWAMCO-4 model has been first evaluated through its application in:

  • The Atlantic sector (at 6°W, between 47°S and 58°S) in Austral spring 1992
  • The mesoscale iron enrichment experiment SOIREE , in latte summer 1999 south of Australia (61°S, 140°E)
  • The ice-free Southern Ocean Time Series station KERFIX (50°40S, 68°E) for the period 1993-1994
  • The sea-ice associated Ross Sea domain (Station S; 76°S, 180°W) of the Antarctic Environment and Southern ocean Process study AESOPS in 1996-1997
  • The North Atlantic Bloom Experiment NABE (60°N, 20°W) in 1991.

Actually a simplified version of the SWAMCO-4 model is implemented in the 3D ice-ocean model Orca-LIM in the domain south of 30°S.

List of projects

  • BELCANTO I
  • BELCANTO II - Assessing the sensitivity of the Southern Ocean’s biological pump to climate change
  • BELCANTO III - Integrated Study of Southern Ocean Biogeochemistry and Climate Interactions in the Anthropocene
  • SIBClim - Sea Ice Biogeochemistry in a CLimate change perspective
  • CARUSO - Carbon dioxide uptake by the Southern Ocean
  • IRONAGES - Iron Resources and oceanic nutrients-Advancement of Global Environment Simulations
  • Si-WEBS - Natural and anthropogenic modifications of the Si cycle along the land-ocean continuum: Worldwide Ecological, biogeochemical and Socio-economical consequences
  • EUR-OCEANS - EUR-OCEANS Network of Excellence; WP on Biogeochemistry with focus on the Southern Ocean system
  • CARBOOCEAN - Marine carbon sources and sinks assessment
  • TRESHOLDS

Research Group Team

  • Promoters: Professor, Lancelot Christiane
  • Post doctorate researchers: Becquevort Sylvie, Schoemann Véronique
  • PhD researcher: Dumont Isabelle
  • Involved partners:
    Belgian partners:
  • International collaboration of ESA in polar marine research is very large including cooperation with European, US, Australian and New-Zealand research groups.
    • (i) Iron biogeochemistry:
      H. de Baar, Royal-NIOZ, Texel, The Netherlands
      G. Sarthou, LEMAR, UBO, Brest, France
      M. van Leeuwe and J. Stefels, RUG, Groningen, The Netherlands
      M. Boye, LEMAR, UBO, Brest, France
    • (ii) Phytoplankton ecology :
      W.O. Smith, VIMS, Virginia, USAl
    • (iii) Microbiology :
      M. Goutx, Marseille, France
      T. Bouvier, Montpellier, France
      C. Brussard, Royal-NIOZ, Texel, The Netherlands
      T. Bouvier, Ecosystèmes Lagunaires, Montpellier, France
    • (iv) Biogeochemical Modeling :
      N. Metzl, LBCM, Université Paris VI, France
      O. Aumont, LSCE, Paris, France
      S. Nicols, T. Trull, and B. Pasquer, ACE, Hobart, Australia
      H. de Baar
      M. Boye & P.Tréguer
  • International networks
    • SOLAS. C. Lancelot in the Scientific Steering Committee and V. Schoemann, scientific secretary of Focus I of international SOLAS
    • EU Network of Excellence EUR-OCEANS: C. Lancelot member of the Scientific Steering Committee and S. Becquevort representative of the SO system in joint activity “ end-to-end ecosystem”
    • SCOR working Group 120 Marine phytoplankton and global climate regulation: the Phaeocystis species cluster as model. C. Lancelot member of the Scientific Steering Committee.
    • ICED (Integrated analyses of circumpolar Climate interactions and Ecosystem Dynamics in the Southern Ocean). C. Lancelot member of the Scientific Steering Committee.

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