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Period: 1996-05-06 - 1996-05-10
Location: Liège, Belgium
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- Université de Liège; Faculté des Sciences; Département d'Astrophysique, Géophysique et Océanographie; GeoHydrodynamics and Environmental Research group (GHER), more, organiser
Modelling ecosystems in a sustainable development perspective is a truly interdisciplinary challenge.
Biogeochemical cycles cannot be considered independently of the hydrodynamic constraints exerted on them.
Hydrodynamic processes the time scales of which correspond to the time scales of biological populations, capture these populations in their physical spatial structures (the so-called "ecohydrodynamic adjustment") and the frequency and persistence of the latter command the speed of the exchanges between the marine biosphere, the ocean reservoirs and the atmosphere.
It is difficult to see how a simple model could be used to describe ecosystems and biogeochemical cycles. On the one hand, geochemical and ecological processes are strongly correlated with physical processes by the resonant interactions and subsequent scale matching of the ecohydrodynamic adjustment; in addition, they live on nutrient supplies which are partly regenerated in the water column - hence subject to the caprices of local hydrodynamics -, partly imported into the system through the boundaries (bottom-sediments, coasts, air-sea interface,...) with a spatial variability which, inevitably, is imprinted on the system's kinetics. On the other hand, the complexity and diversity of ecological and geochemical interactions webs leaves little hope for the development of realistic management models including too simpliste biology and geochemistry.
Yet, there are limitations, -if not on computing power and computing time in a foreseeable future-, on the volume of computer products, the -technical and human- ways and means of exploiting them for the advancement of our basic scientific understanding or the development of rational management schemes, in any reasonable time.
A trade-off must be found between physical and biogeochemical complexity of the models.
When the hydrodynamic constraints play a cogent part (as in fronts, upwellings...), there is a tendency among the hydrodynamicists to investigate the physics in details and try to get away with a very simple representation of the biology.
The purpose of the Colloquium is to provide a forum for discussing the success and shortcomings of these hydrodynamics-dominated models, inviting biologists and geochemists to report their own progresses (approaching the system from the other side, so to say) and identify the bases for the development of models of optimal complexity.