SPATIOTEMPORAL VARIABILITY OF THE THERMOHALINE AND BIOGEOCHEMICAL PROPERTIES AND DISSOLVED ORGANIC-CARBON IN A COASTAL EMBAYMENT AFFECTED BY UPWELLING - THE RIA-DE-VIGO (NW SPAIN)

Hydrographic sampling was carried out along the main axis of the Ria d e Vigo, from May 1994 to September 1995, to observe the spatio-tempora l evolution of hydrographic and biogeochemical properties of the water column. Meteorology controls mainly the hydrography and biogeochemist ry of the Ria. Two periods can be distinguished on a seasonal time-sca le: the upwelling season. from March to October and the non-upwelling season, from November to February. A strong coupling was observed betw een meteorological, hydrographic and biogeocbemical processes. The Ria behaves like an extension of the shelf during the upwelling season an d like a partially mixed estuary during the non-upwelling season. Diss olved organic carbon was related to the thermohaline properties in the whole water column, and with oxygen and chlorophyll a in the surface layer. Extreme values were recorded during the upwelling season: the h ighest values (> 100 mu M), in the surface layer during upwelling rela xations and the lowest values (< 70 mu M), in the bottom layer in upwe lled waters. Dissolved organic carbon maxima decrease shelfward thus s uggesting export of dissolved organic carbon, in addition to particula te organic carbon, from the Ria to the shelf. (C) 1998 Elsevier Scienc e B.V.