1. Oceanographic conditions in Galicia and the Southern Bay of Biscay and their influence on the Prestige oil spill M. Ruiz Villarreal, P. Otero, C. González Pola, A. Lavín, G. Díaz del Río and JM Cabanas Instituto Español de Oceanografía manuel.ruiz@co.ieo.es

2. Oil spill transport - Main driving agent was wind, but coastal circulation apparently has an impact in stranding points and affected area - What is the fate of the fuel deposited at the bottom and fuel in the water column? Impact on ecosystems - System subject to strong interannual variability. Difficult to ascribe an effect to the impact of oil spill. Conditions following spring are determinant for the response of the ecosystem Oceanographic conditions during the Prestige oil spill: need for analysis

3. Historical IEO Demersales survey Demersales0903Hidroprestige0303 Accion Especial Prestige Historical IEO Pelacus survey Prestige Plataforma1202 Prestige Plataforma0103 IEO Standard Sections

4. Summer 2002 to Autumn 2003 Upwelling index at 43N 11W

5. Salinity 100db Autumn 2002 Autumn 2003 Ruiz-Villarreal et al., Oceanographic conditions in Galicia and the Southern Bay of Biscay and their influence on the Prestige oil spill, Submitted to MPB, 2005

6. 123 1 2 3 Poleward Slope current carrying subtropical waters Downwelling conditions Poleward slope current Freshwater plumes

7. Poleward current domain River plumes

8. PLATERIAS project

9. Coastal circulation before stranding of 2nd spill

10. 2nd spill drift simulation: wind + coastal circulation

11. Summer 2002 to Autumn 2003 Upwelling index at 43N 11W

12. Spring transition in Galicia Autumn-Winter Spring   at 5 dbar Geostrophic vel. at 5 dbar - Upwelling pulses - Poleward current waters exported offshore during pulses - Eddy activity - Freshwater plumes - Poleward current at the slope (warmer and saltier)

13. Garcia-Soto, Prestige oil spill and Navidad flow, JMBA, 2004

14. Santander slope Cantabrian. Intrusion of subtropical waters Ruiz et al. Submitted to MPB, 2005

15. NCEP wind vector progressive diagram

16. Early commencement of spring in the Cantabrian Sea Upwelling in the Cantabrian Sea during Pelacus

17. December January February March MERCATOR-OCEAN PSY2 1/12º

18. Galicia Bank * Prestige wreck mooring

19. Conclusions - Circulation during Prestige accident: - end autumn-winter situation. Shelf and slope intense circulation: river plumes, slope current - more research needed on response of plumes and slope current to wind forcing (Platerias and Zotracos projects) - propagation in the Cantabrian driven by the poleward current needs further analysis: poleward flow in December, but no signals of intrusion of subtropical waters - Circulation during spring - Cruises performed during “spring transition”: upwelling pulses influence circulation, poleward weakens and is exported offshore - Early commencement of spring in the Cantabrian, and this could have affected ecosystem response - Galicia Bank impact on circulation: tidal distortion, mesoscale activity… Further research is needed. Seamount ecosystem?