Biological-physical coupling in the equatorial
Pacific during the 1997-98 El Niņo

Peter Strutton, Ph.D.
Monterey Bay Aquarium Research Institute

Friday, April 3, 1998
12:00 Noon—Pacific Forum

In late 1996, MBARI deployed bio-optical and chemical instrumentation on two moorings in the central equatorial Pacific to monitor the biological changes associated with El Niņo, as well as validate ocean-color satellites. By combining bio-optical and physical time series, we were able to describe the physical progression of El Niņo onset, from reversal of the trade winds in the western equatorial Pacific, through eastward propagation of equatorially trapped Kelvin waves and advection of waters from the nutrient-poor western equatorial warm pool. The physical perturbations were tightly coupled to fluctuations in phytoplankton biomass and quantum yield of fluorescence.

Our data suggest that primary productivity in the central equatorial Pacific was reduced to 50% of the climatological mean with the onset of the current El Niņo event.

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