Phytoplankton rate processes in the oligotrophic waters of the central North Pacific Ocean

Abstract

The central North Pacific is one of the more oligotrophic regions of the world oceans. There the particulate organic nitrogen:cabon ratio of surface waters is variable and less than the Redfield ratio of 16N:106C by atoms. The phytoplankton P/B ratio based upon both C and N assimilation rate varied directly with the particulate matter PON:POC ratio as did the productivity index [mg C (mg chl a)⁻¹h⁻¹]. At steady state the doubling time of the phytoplankton, the turnover time of the limiting nutrient supplied via herbivore grazing, and the time for herbivores to filter a unit volume of water would be equivalent. They appear to be of the order of 5–9 days based on present methodology and straightforward interpretation of its results.