Seasonal and interannual changes in planktonic foraminiferal production in the North Pacific

Abstract

It is well established that there are distinct seasonal cycles in the production of plankton, that vary both geographically and in terms of phytoplankton-zooplankton coupling1 . Only recently have attempts been made to measure seasonal variability in the flux of various biogenic components from the ocean surface to the sea-floor2–4 and to relate this flux to local hydrographic conditions5. For example, a simple inverse relationship has been found between sediment flux to the seafloor and sea-surface temperature in the Sargasso Sea5. A three-year sediment trapping project in the subpolar North Pacific has allowed us to document both seasonal and interannual variability in the flux of planktonic foraminifera from the sea surface. We propose a model, based on the temperature preferences of planktonic foraminiferal species, the thermal structure of the upper water column and food availability, to explain the observed changes over time in foraminiferal production and flux.