Spatio-temporal variability of the thermohaline and biogeochemical properties and dissolved organic carbon in a coastal embayment affected by upwelling: the Ría de Vigo (NW Spain)

• Published in: Journal of marine systems 1998, Vol.14 (1), p.135-150
• Main Authors: Doval, M.D., Nogueira, E., Pérez, Fiz F.
• Format: Article
• Language: English
• Subjects: biogeochemical; DOC; Earth sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Geochemistry; hydrography; Marine; Mineralogy; non-upwelling; Physical and chemical properties of sea water; Physics of the oceans; Ría de Vigo (NW Spain); Silicates; upwelling; Water geochemistry
• ISSN: 0924-7963; 1879-1573
• DOI: 10.1016/S0924-7963(97)80256-4

Hydrographic sampling was carried out along the main axis of the Ría de Vigo, from May 1994 to September 1995, to observe the spatio-temporal evolution of hydrographic and biogeochemical properties of the water column. Meteorology controls mainly the hydrography and biogeochemistry of the Ría. Two periods can be distinguished on a seasonal time-scale: the upwelling season, from March to October and the non-upwelling season, from November to February. A strong coupling was observed between meteorological, hydrographic and biogeochemical processes. The Ría behaves like an extension of the shelf during the upwelling season and like a partially mixed estuary during the non-upwelling season. Dissolved 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 highest values (> 100 μM), in the surface layer during upwelling relaxations and the lowest values (< 70 μM), in the bottom layer in upwelled waters. Dissolved organic carbon maxima decrease shelfward thus suggesting export of dissolved organic carbon, in addition to particulate organic carbon, from the Ría to the shelf.