A PERSISTENT UPWELLING OFF THE CENTRAL CANTABRIAN COAST (BAY OF BISCAY)

North Atlantic Central Waters were detected near the surface in some locations off the Central Cantabrian Coast (Bay of Biscay). This feature suggests an upwelling process taking place in the season of the thermal stratification which is persistent throughout the summer. The exact mechanism of formation is unknown but the wind driven currents are probably the main force. The prevailing winds off the Cantabrian coast are northeast during summer, generating westward superficial currents that produce an Eckman transport offshore. Factors such as shape of the coast and slope topography maybe modulators. Although the upwelling was subsuperficial, our results suggest that cold and nutrient rich waters reached the surface previously. The biomass distribution of phytoplankton varied according to the upwelling and different populations could be recognized. In stations not affected by upwelling phytoplankton occured mainly on top of the thermocline, whereas in those affected by upwelled waters it was concentrated near the surface. The mean size and composition of the populations were also different, and two distinct types could be recognized and related to nutrient concentrations. © 1990.