THE MEDITERRANEAN-SEA, COASTAL AND DEEP-SEA SIGNATURES OF CLIMATIC AND ENVIRONMENTAL-CHANGES

At great scales of time and space, the dynamics of the Mediterranean S ea, a concentration basin, are mainly linked to its freshwater budget. This budget is subject to evolutions due to man's use of freshwater a nd to climatic changes affecting precipitation and/or evaporation. Mar ine dynamics and Atlantic, atmospheric and terrestrial inputs are stro ng constraints for the geochemical behaviour of the Mediterranean Sea. From measurements made during the last decades in the deep western wa ter, it appeared that temperature, salinity, nutrients and trace metal concentrations were changing with time. In spite of its depth, the Me diterranean Sea looks like a coastal ocean, according to its coast len gth, watershed and number of inhabitants and to its fast response to c limatic and environmental changes. The changes discovered in deep homo geneous waters are signatures of evolutions occurred in the surface la yer. But in this layer and particularly in coastal waters, climatic an d/or environmental trends may be masked by seasonal and interannual va riabilities of not only physical and chemical characteristics but also climatic forcing or anthropic inputs. Analyses of river runoff, atmos pheric inputs or climatic trends together with marine evolutions indic ate constraints concerning probable changes in the coastal sea and/or in the surface water and processes involved at the interfaces. Moreove r, changes observed in coastal or deep-water constitute new constraint s for the modelling of the marine circulation and the transfer of matt er.