SYMPOSIUM on Marine Accidental Oil Spills The Prestige oil spill. A vast learning exercise. Joan ALBAIGÉS* Department of Environmental Chemistry, CID-CSIC, Jordi Girona Salgado, 18-26, 08034 Barcelona ABSTRACT The Prestige oil spill has been the most important marine pollution accident affecting ever the Spanish coasts. Although the NW Atlantic belt has been periodically affected by accidental oil spills (e.g. Polycommander, 1970; Urquiola, 1976; Aegean Sea, 1992), the present one was unique with respect to the heavy nature of the spilled oil, the depth of the wreck, as well as the extension of the affected area, bearing important scientific and technological challenges. In the absence of a national contingency plan to react to the massive oil spill, the scientific community, with the support of the Spanish Administration, attempted to provide answers for the most urgent and relevant issues. These were the modelling of the oil behaviour both in the wreck and in the sea surface, the prediction of the oil drift and fate, the determination of the spatial and temporal extent of contamination of the different marine biotic and abiotic compartments, and the impact on the different shelf communities and their trophic structure, the assessment of shoreline cleaning procedures and the assessment of the socio-economic impact of the spill. A general conclusion to be drawn from these studies is that with the exception of the coastal areas directly oiled by the spill, it was difficult to identify major impacts in the sub-tidal zone and the continental shelf. Significant effects were neither detected in demersal communities even though recruits were bound to the same drift of the oil. This may be attributed to the physical characteristics of the oil. Overall, final conclusions will only be drawn as the assessment is supported by the availability of pre-spill data (e.g., PAH concentrations in biota, bacterioplankton activity, abundance and distribution of fish resources and fishing activity), and data collection is extended much beyond the traditionally accepted period of a few years after the spill event. The interpretations of long-term impacts, however, are often hampered by the concurrence of the chronic release of hydrocarbons into the sea from numerous sources. Therefore, there is a need for continuous up-dating of knowledge and development of new concepts and tools to identify oil spill sources and to understand their fate and effects in the marine environment. This vast effort is being reflected in the open literature and a particular major outcome has been the enhancement of scientific networking in different areas, illustrated by large projects such as ESEOO (operational oceanography), IMPRESION (biological effects) and CONTINMAR (contingency planning), to mention just a few. In this context, the AMPERA network was also established to provide a platform where governmental policy-makers and scientists from European coastal countries could meet to discuss R&D aspects of accidental marine pollution (AMP), and to provide guidance to implement EU-wide measures as required. The presentation will summarize the whole strategy made in place and illustrate the progress of the activities so far carried out. We hope this effort will play an important pressure upon the need for a better protection of the marine environment through the implementation of new or improved prevention mechanisms and response actions, based on sound scientific principles. *On behalf of the Scientific Coordination Commission (CCC). 1