Paleoproductivity from benthic foraminifera abundance: Glacial to postglacial change in the west-equatorial Pacific

Surface productivity is correlated with the rate of accumulation of benthic foraminifera on the deep-sea floor. As a rule of thumb, for each 1 mg of organic carbon arriving at the sea floor, one benthic foram shell >150 μm is deposited. The correlation can be used to reconstruct organic flux to the sea floor in the past, and hence the productivity of past oceans. Applying the appropriate equations to box core data from the Ontong Java Plateau in the western equatorial Pacific, we found that productivity during the last glacial maximum exceeded present productivity by a factor of between 1.5 and 2.0, with intermediate values for the mid-transition period. Accumulation of benthic foraminifera was depressed on top of the plateau during the glacial and transitional period, presumably because increased winnowing removed part of the food supply.