NUTRIENT FLUXES TO THE BAY OF BISCAY FROM CANTABRIAN RIVERS (SPAIN)

Nutrient fluxes to the Bay of Biscay from the Cantabrian basin have be en quantified for the first time. Data between 1981 and 1995 of the ma in 16 Cantabrian rivers from the COCA monitoring programme have been u sed. Values of water flow and dissolved inorganic nitrogen (DIN), phos phate and silicate concentrations have been taken. Equations are propo sed to quantify the fluvial nutrient contributions to the Cantabrian S ea. The annual average of continental outputs to the Bay of Biscay fro m the Cantabrian basin is 16.1 x 10(9) m(3) of freshwater, 1.0 x 10(9) mol of N in DIN, 0.062 x 10(9) mol of phosphate and 1.2 x 10(9) mol o f silicate. In comparison with the French rivers, those of the Cantabr ian have small fluxes and their outflow is very disperse, not forming large coastal plumes. From April to September, when the primary produc tion is relatively important, the DIN contribution to the Cantabrian c oastal reservoir is 10 %. Coastal fertilisation due to continental wat ers could be considered as negligible and only influences areas very c lose to river mouths, except for the Nalon River. Its flux represents 33 % of nitrate, 39 % of phosphate and 15 % of silicate of the total c ontinental inputs of nutrients to the Cantabrian Sea. (C) Elsevier, Pa ris.