Systematic ENSO-driven nutrient variability recorded by central equatorial Pacific corals

Date: 2013-08-16

Creator: Michèle LaVigne, Intan S. Nurhati, Kim M. Cobb, Helen V. McGregor, Daniel, Sinclair, Robert M. Sherrell

Access: Open access

Variations in ocean productivity are driven largely by nutrient supply to the photic zone, but temporal records of nutrient variability are sparse. Here we show scleractinian coral P/Ca proxy records of variations in phosphate concentrations during El Niño Southern Oscillation (ENSO) cycles in the central equatorial Pacific. Covarying P/Ca records in Porites corals from Christmas and Fanning Islands show a regional ∼40% decrease during the upwelling relaxation of the 1997-1998 El Niño, consistent with less frequent nutrient measurements from this area. Similar ∼35-45% skeletal P/Ca decreases occur during the 1982-1983 and 1986-1987 El Niño events, which predate satellite color and regional nutrient measurements. After each El Niño event, nutrient increases lag temperature recovery by 4-12 months, likely reflecting uptake by massive phytoplankton blooms that followed resumption of upwelling. The results support the utility of coral P/Ca to probe the mechanisms linking ENSO, equatorial upwelling, and carbon cycling in the past. © 2013. American Geophysical Union. All Rights Reserved.