Characterization of El Niño, La Niña, and normal conditions through planktonic foraminifera (2006–2007) in the southeastern Pacific

Abstract

We conducted a study to characterize the foraminiferal association off south-central Chile under positive (January to December 2006), neutral (January to June 2007), and negative (July to September 2007) thermal anomalies, which coincided approximately with El Niño (EN), normal (NC), and La Niña (LN) conditions, respectively, using samples collected in a sediment trap located off Concepción at 2300 m depth. During the three environmental conditions, total species richness was 19, with 18 species present during EN, 14 during NC, and 14 during LN. Moreover, a typical association of subantarctic waters was observed during NC and LN, but not during EN, when we found a mixture of cold and warm water species as well as higher foraminiferal and calcium carbonate fluxes. However, diversity was very similar under the three conditions. We observed significant differences in foraminiferal and calcium carbonate fluxes between NC and EN, with higher values during the warm phase.