Assessment and monitoring activities constituted two main tasks of the emergency response system implemented by the regional government of Cantabria (north Spain) after the Prestige oil spill. The assessment covered four types of environmental units: estuaries, rocky shores, sand beaches, and subtidal areas, up to a 300-m depth. Monitoring procedures included the chemical quantification of total hydrocarbons and polycyclic aromatic hydrocarbons in water, sediments, and benthic organisms (clams and goose barnacles), and the analysis of structural changes in intertidal communities.
Disturbance of oil cover was significantly more extensive in coastal areas, rather than in estuarine areas, where 50,000 m2 were directly covered by fuel. Otherwise, the presence of oil in subtidal areas was a rare event. Results from the bioeffects analyses were in agreement with the overall impact assessments, pointing to the coastal habitats as the areas where the bioavailability of toxic components from the Prestige spill presented a significant level of risk.