EFFECTS OF COASTAL UPWELLING ON THE SPRIN G PRIMARY PRODUCTIVITY OF MEJILLONES-DEL-SUR BAY (ANTOFAGASTA, CHILE)

Primary production studies were conducted during September-October 199 0 at Mejillones del Sur Bay. The main objective of this study was to a nalyze the influence of the upwelling events on the spring primary pro ductivity of the Bay, and the potential rol of atmospheric nitrate. Th e concentration of nitrate was measure in aerosols at Mejillones; ocea nographic conditions were studied in two stations, one in the Bay and the other at Punta Angamos. Coastal upwelling was also studied using h ourly wind data from Aeropuerto Cerro Moreno and wind records from the Bay. Results show that the spring dynamic of the primary production o f the bay is controlled by the upwelling events occurring at Punta Ang amos, the availability of nitrogen is the most important factor. The h ighest production rate (2342 mg C m-3 hr-1) was measured during the de velopment of a red tide of the autotrophic ciliate Mesodinium rubrum. The nitrate contained in aerosols plays a minor rol in the primary pro ductivity during spring.