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Response of the Southern Ocean global ecosystem to physical and trophic constraints

Antarctica phase IV (1997-2000)

Response of the Southern Ocean global ecosystem to physical and trophic constraints


Dr Jean-Henri Hecq
Université de Liège
Ecohydrodynamique - GHER
Sart Tilman - Physique B5
B-4000 LIEGE
Phone: +32 (0)4 366 36 46
Fax: +32 (0)4 366 23 55


Dr Georges Pichot
Management Unit of the Mathematical Model of the North Sea (MUMM)
Belgian Royal Institute of Natural Sciences
Gulledelle, 100
Phone: +32 (0)2 773 21 22
Fax: +32 (0)2/ 773 69 72

Prof. Vincent Demoulin (Université de Liège)
Université de Liège
Laboratoire de Botanique
Sart Timan - B22
B-4000 LIEGE
Phone: +32 (0)4 366 38 53
Fax: +32 (0)4 366 28 53


The research consists of a multidisciplinary study of the biodiversity and productivity of the global ecosystem of the Southern Ocean in a context of variation of the environmental and climatic conditions. It develops an approach based on the analysis of sub-ecosystems at specific time and space scales and on the interconnection of these systems by means of a proper modelling.

The studied sub-ecosystems are :

  • the planktonic ecosystem, which is the target of the study of the processes relating to biodiversity, dynamics and phyto-zooplanktonic interactions (specific scale : water column and ice layer);
  • the pelagic ecosystem, with which is associated the macrozooplankton and in particular the krill (specific scales : Ross Sea and decade);
  • the ecosystem of the higher trophic levels (specific scales : Southern Ocean and century).

It relates to the conceptualization, the parameterization and the validation of a coupled 3D numerical model integrating the whole of the physical and biological processes which control the dynamics and the variability of the global ecosystem of the Southern Ocean.
The biological module of this model will be primarily centred on the zooplankton (in particular the krill) and the higher predators, but will take into account phytoplanktonic variables limiting the feeding of the herbivores.
In a second step, the coupled 3D model will be applied to the evaluation of the response of this ecosystem according to various scenarios of forcing taking account of natural factors as well as anthropogenic.


  • To understand how the physical and biological processes coupled at various scales control the functioning and the evolution of the global ecosystem of the Southern Ocean. More specifically, the goal is to quantitatively determine how this ecosystem reacts to the whole of the physical constraints, be it directly - owing to the effects of the hydrodynamics, the vertical structure of the water column, the ice cover and the penetration of light in the water, or indirectly - owing to the trophic conditions, qualitative (the favoured species or group of species) and quantitative (the quantity and the productivity of these species) which are imposed by the physical constraints.
  • To determine, in a perspective of help to the decision-making process as regards environmental protection, how this system would respond to environmental and climatic changes, natural or anthropogenic.

These goals are pursued within the framework of an international programme on the global ecosystem of the Southern Ocean in the Ross Sea in collaboration with the Italian National Research Programme on the Antarctic (PNRA) and, in particular, during campaigns in the Ross Sea planned for 1997-98 and 1998-99.

Specific expertise

Dr J.-H. HECQ: Ecosystem functioning and modelling

  • Phytoplankton response to physical (light, including UV and water column vertical structure) and trophic forcing (grazing, biodegradation, biosedimentation).
  • Extension of the 1D vertical ecological/hydrodynamical ECOHYDROMVG model to lower trophic levels.
  • Phyto- and zooplankton response to physical forcing owing to sea ice.
  • Modelling the dynamics of krill populations.
  • Modelling of trophic processes.
  • Phyto- and zooplankton distribution.
  • Scenarios for evaluating ecosystem resilience and evolution in function of environmental and climatic forcing.
  • Data collection and diffusion by means of telematics.
  • Overall synthesis of the results of the integrated project.

Dr G. PICHOT: Physical modelling

  • Numerical adaptation of the 1D ecological/hydrodynamical ECOHYDROMVG model.
  • Introduction of the ice freezing in the ECOHYDROMVG model and simulation over a standard seasonal cycle.
  • Introduction of biological equations in the OIL-SPILL-96 model.
  • Extension of the ECOHYDROMVG model to a two dimensional horizontal model for the Ross Sea and adaptation of the MUMM-SEAICE model.
  • Adaptation of the MUMM-3D hydrodynamical model to the Ross Sea circulation.
  • Biological/hydrodynamical coupling of the adapted MUMM-3D model.
  • Sensitivity experiments for assessing interannual and regional variability and ecosystem resilience.
  • Scenarios for evaluating the response of the Southern Ocean to environmental and climatic forcing.

Dr V. DEMOULIN: Role of the picophytoplankton

  • Molecular techniques for the characterization of picophytoplankton (cloning, sequencing and hybridation of marked probes relative quantification).
  • Vertical structure of picophytoplankton diversity and abundance.
  • Mesoscale horizontal structure of the diversity and abundance of picophytoplankton.
  • Relationship between the diversity and abundance of picophytoplankton and the sea ice.

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