We have calculated an upwelling index for each month over a 17-year period (1969-1985) for a point off the western coast of Spain. We interpret April through September values of the index to indicate the flux of nitrate-rich water into the Spanish Rias. The index representing the 6-month upwelling series has been correlated with an index representing the conditions of mussels grown during that season on rafts in Ria de Arosa. Two seasons represent extreme upwelling conditions over the 17-year sampling period: 1977 when the upwelling index was the highest, and 1983 when it was the lowest. A comparison of the condition of mussels during these years showed that meat content was double in 1977. We suggest, by this study, that long range forecasts of synoptic scale weather patterns could be used to predict the potential nutritional value of mussels harvested in the rias of Spain.

Observations and numerical simulations of upwelling along the Galician coast of Spain during April 1982 are presented. In situ measurements include shipboard determinations of hydrographic and biological parameters from a grid of stations covering the continental shelf from Cape Finisterre to Ria de Vigo, sea level data from Vigo and La Corufia, and wind stress estimates derived from the ship winds and from surface pressure charts. Sea surface temperature information and pigment concentration information have been obtained from a sequence of satellite images from the NOAA 7 advanced very high resolution radiometer and the Nimbus 7 coastal zone color scanner, respectively. Since the Cape Finisterre sector of the Iberian peninsula is characterized by an abrupt change in coastline orientation, wind-driven upwelling can occur in that region over a 270 ø range of wind direction. These data document the evolution of upwelling and the resultant coastal circulation in response to two wind events that occurred over a 10-day period. Salient features of the circulation include a southward coastal jet and a northward flow further offshore along the western coast. Numerical simulations of the coastal currents, the vertical excursion of a density interface from a static equilibrium position, and coastal sea level are conducted using a wind patch characterized by constant direction and negative curl. The simulations show that during these wind events, the greatest upwelling will occur either at Cape Finisterre or along the northern coast as was observed in this case and as has been reported by others. It is suggested on the basis of the analysis of the sea level records and on the numerical simulations that wave disturbances propagate northward along the coast at a speed of 120-160 km/day. Finally, it is speculated that much of the organic material formed during upwelling events north of the Cape Finisterre is advected out to sea northwest of the cape. INTRODUCTION The western coast of the Iberian peninsula is the site of seasonal wind-driven upwelling from March through October [Wooster et al., 1976]. This upwelling is part of a general system that extends southward to about 15øN. Along the Galician coast of Spain (Figure 1), the upwelling is most intense from April to August [Fraga, 1981] with the region between capes Finisterre and Ortegal exhibiting the coldest surface temperatures. During the remainder of the year, the winds are predominantly from the south, or downwelling favorable. The irregular configuration of the Galician coastline and the general circulation of the offshore water masses add complexity to the response of the coastal waters to the wind. For instance, south of Cape Finisterre are five embayments, or rias, which cause enhancement of the upwelling through current-bathymetry interactions [Blanton et al., 1984]. Also, the coastline abruptly ends its north-south orientation at Cape Finisterre and continues in an east-west direction east of Cape Ortegal. Thus upwelling favorable winds span a 270 ø range in di...

Abstract. The Galician shelf off NW Spain (43N ø 9W ø) exhibits mesoscale spatial and temporal changes in biological productivity associated with upwelling. Spatial heterogeneity results from local geomorphic and land-sea interactions superimposed on the large scale atmospheric processes that produce upwelling. Wind-induced upwelling events, commonly of short (i.e., week) duration, are more common in the summer than in the winter. A series of cruises, including some time series sampling, and satellite imagery analysis showed that surface upwelling was more common and persistent on the northern coast compared with the western coast off the coastal embayments, the Rias Bajas. Nearshore off the rias, coastal runoff, which is greater in the rainy winter/spring versus the dry summer, affected upwelling. In early summer, upwelling less often reaches the surface because of increased water column stratification associated with lower surface salinities and thus upwelling is not detected by satellite imagery. Conversely, in late summer, upwelling more often reaches the surface because coastal runoff is reduced during the dry summer months and the water column tends to be less stratified. Plankton biomass and rate processes along the Galician shelf reflected both ambient hydrographic conditions as well as prior history of upwelling or downwelling. Phytoplankton and bacterioplankton were in greatest abundance during upwelling conditions (June through August); in contrast, both zooplankton and fish larvae exhibited highest abundances in March, when there were upwelling conditions prior to our cruise. Spatial differences in the duration and frequency of upwelling events, in combination with advection of water masses, are critical to the patterns of water column productivity and sardine fisheries production off the Galician coast. More persistent upwelling at this NW corner of the Iberian peninsula supports large sardine fisheries because zooplankton and larval fish populations have time to respond to the higher primary production. Farther down the western Galician coast, the episodic upwelling and resultant intermittent primary production does not support a stable food supply needed to support fisheries. Times series sampling revealed mean response times of bacteria, phytoplankton, and zooplankton to be on the order of a day, days, and weeks, respectively. Sardines showed no spawning response in the relatively short time series sampling. The observed distributional patterns of fish eggs and larvae showed some offshore transport of fish larvae that were spawned inshore during upwelling periods and aggregation of larvae in a convergence zone northwest of Cabo Villano.