Why do we use ecosystem models?

Ecosystem models can be used both to understand better the functioning of the marine ecosystem, and to provide indications of how the ecosystem is likely to change in response to changes in human activities. These models allow scientists to better visualise how species are influenced by each other and by physical conditions.

Of particular concern to environmental managers is the excessive production of marine algae, which appear as a "dirty" brown foam on the beaches in late spring. This can be caused by an over-supply of nutrients (nitrates and phosphates) from rivers and the atmosphere, a phenomenon called eutrophication.

To overcome this problem European governments work to reduce emissions of nitrates and phosphates. They take initiatives such as the improvement of municipal wastewater treatment facilities and measures relating to industrial effluents and agricultural use of fertilisers.

In fact, in the frame of the North Sea Conferences, the London Declaration (1998) suggested that the input of nitrogen and phosphorus to the North Sea should be reduced by 50% over the period 1985-1995. Details of thereductions effectively attained during the period 1985-2000 are available. More recently, in 1998, European countries facing the problem of eutrophication agreed, within the OSPAR strategy on eutrophication, to make every endeavour "to reach, by 2020, and maintain a healthy marine environment where eutrophication does not occur".

Ecosystem models can be used to provide a better scientific basis to reach this by assessing the probable consequences of environmental policy on phytoplankton levels. The models allow alternative scenarios to be simulated, such as reductions of both or either nutrient by different percentages.

A further source of data for ecosystem model validation will be provided by satellite images from Envisat/MERIS, which was launched on March 1, 2002.

MUMM's ecosystem modelling activities are funded by the Belgian Science Policy Office "Sustainable Development North Sea program" and are carried out in collaboration with the "Ecologie des Systèmes Aquatiques" (ESA) lab of the Université Libre de Bruxelles (C.Lancelot), the College of Oceanic and Atmospheric Sciences of Oregon State University (Y.Spitz), and the Laboratory of Ecology and Systematics of the Vrije Universiteit Brussel (N.Daro) in the AMORE project. Further details on the project can be obtained from the coordinator.

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