IMIS

Seasonal and interannual changes in the flux of planktic foraminifera were studied in the Humboldt Current System off Coquimbo (30°S, 73°,15W), using material collected by time series sediment traps located at 2300 m water depth and 100 nautical miles from the coast. The almost continuous record spans 8 years (1991-1998) with a temporal resolution of 6-13 days. Field work was carried out during the El Niño event of 1991/1992 (6 months), under normal conditions in 1993/1994 (1 years) and the strong 1997-1998 had only a limited impact on the planktic foraminifer flux. The seasonal flux pattern of planktic foraminifera was marked by high fluxes during austral late winter - early summer (August-January) and low fluxes during the fall - early winter period (March-July). Five species contributed ca. 90% of the total flux of planktic foraminifers: Globigerina bulloides, Neogloboquadrina incompta, N. pachyderma, N. dutertrei, and Globigerinella calida. The most significant El Niño-related signal was a remarkable increase in the flux and abundance of species that, under normal conditions, only accounted for 10% of the planktic foraminiferal assemblage.