A geographical information system for some Mediterranean benthic communities

This paper describesa regional geographical information system (GIS) for some Mediterranean benthic communities. The area covered by the GIS lies between the cities of La Ciotat and Giens in southeast France. The distinctive characteristics of this GIS compared with others usuallydescribed in the literature, are that all its layersdescribethe same theme but as seen at different moments with different scales and techniques used by different oceanographers. A method was devised to synthesize, on a pixel basis, the content of all these layers. Each pixel within each layer is weighted with a function relating to the year of survey, the sampling technique and the scale of the original map corresponding to that layer. The synthesis map is composed of the highest weighted values found in the set of layers.Alsoat each pixel,conflictsbetweenthe contents oflayers are quantified and mapped.