spatio-temporal variability of inorganic and organic nutrients in five galician rias (nw spain)

The spatial variability of inorganic (nitrate, nitrite, ammonium, phosphate and silicate) and organic (dissolved organic carbon) nutrients in five Galician rias (Vigo, Pontevedra, Arousa, Muros and Ares-Betanzos) was assessed by considering average values for the upwelling and downwelling periods. Inner stations were significantly different from middle and outer stations, especially during the downwelling period. Spatial differences between the five rías, tested by means of a multivariate analysis, were found in both periods. The behaviour of inorganic and organic nutrient variables was also significantly different between periods with and without shellfish harvesting closures due to the occurrence of toxic phytoplankton species.