The diversity of ecosystems is an aspect of "biodiversity" which has recently become a popular notion. It refers to the diversity of life of all forms, beginning with the genetic heritage and extends to the ecosystems on which the biosphere is built (UNESCO, Rio de Janeiro, 1992). As a whole the various biological levels are marked by an alarming reduction in their biodiversity. Structural biodiversity (in terms of numbers, biomass, the composition of species and the population structure of communities) and functional biodiversity (presented as series of interactions between the various trophic levels) are different concepts which most certainly must be related one to the other if one is to have a good understanding of how an ecosystem functions. The project There are two facets of the project: an analysis of the factors which determine the biodiversity of marine ecosystems and the changes in them; the translation of what is known into parameters which can serve as a basis for the policy to be implemented (for example, the species which serve as ecological indicators). Special attention will be paid to the benthos (organisms which live close to or at the bottom of the sea) and the upper trophic levels (fish, seabirds and marine mammals) and their parasites. Activities In the first phase a synthesis will be made of all the information available having to do with the spatial and temporal distribution (structural biodiversity) of the components mentioned above of the Belgian coastal shelf. The data will be used together with an analysis and interpretation of the connection between the biological indicators and the environmental variables to establish criteria for the selection of ecological indicators for sustainable development. Special attention will be paid to sandbanks, not only because of their extreme ecological significance, but also because they are greatly affected by human activities. Comparison with neighbouring areas (open sea, the Belgian East coast) will enable us to evaluate those characteristics which are peculiar to sandbanks. Maps will be made available for use by policy makers. They will not only indicate the places where different species of bird, benthos, fish and their parasites occur, but also the vulnerable areas. The connection between biodiversity and production is of fundamental importance in ensuring that ecosys-tems are efficiently managed. In this respect there are two different approaches which will have to be considered: maintaining the large "visible" species, which often occupy an important position in the food chain, and which, in the policy context, are easy to monitor as ecological indicators; reaching an understanding of the underlying biological relationships (predation, competition) and the structuring interaction with the abiotic environment. The feeding ecology of the different components will be quantified and qualified with special emphasis on the trophic place of those species which serve as ecological indicators. The significance of the primary production of the water column in the benthos structure will be studied to quantify the direct interdependency between the pelagos and the benthos. Models of morphological variation do not always coincide with auto-ecological, molecular and biogeographical models. This is of crucial significance in ecological research, since it implies that morpholo-gical diversity does not necessarily correspond to functional diversity which latter can be either greater or less than the morphological diversity would indicate. We are basing ourselves on the principle that the population genetics of fish (biodiversity at the level of population) constitutes an essential element in understanding the ecosystem of sandbanks (biodiversity at the level of the ecosystem). The choice of which species to study will be determined by what is already known in the fields of ecology and genetics and their significance both as food for birds and the commercial fishery (for example gudgeon). The importance of parasites of fish and seabirds will also be considered as biological and genetic markers. This research is of direct interest to policy makers at the Belgian Federal level for the following reasons: The implementation of the Ramsar agreement of 1971 covering water rich areas and in the framework of which the implementing decrees establishing a protected zone in the Flemish banks (coastal sandbanks) are overdue. The preparation of the next Conference on the North Sea (2000), at which the Belgian Government will draw on the expertise of its own researchers as regards the information available on eutrophication, the deterioration of the habitat, pollution, the extraction of sand and overfishing (including opinions on the proper management of genetic characteristics). The supply of basic information for the optimum management of the natural resources of the Flemish banks, if appropriate, by setting up a marine reserve. Establishing criteria for ecological monitoring of the sustainable development of the North Sea (with priority on the sandbanks). The application of the UNESCO convention on biodiversity signed in Rio de Janeiro (1992). So far none of it has been implemented on Belgian territory. The inventory of the fauna of the Belgian continental shelf is incomplete. The intention of the Federal and Flemish governments of setting up a data bank as a management instrument and including an information system based on geographical coordinates.