Different ways are explored for presenting 12 years of data on phytoplankton species and toxins in shellfish collected along the French coast and within the framework of the French Phytoplankton Monitoring Network. The advantages and difficulties of aggregating data in different dimensions are discussed. For example, graphs appear suitable only for restricted areas, while mapping is necessary for results on regional or larger scales. Within each of these broad categories, considerable care is required when identifying the appropriate type of information and presentation.